About all

Eltroxin 0.1 mg side effects: Eltroxin Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing


Eltroxin Oral: Uses, Side Effects, Interactions, Pictures, Warnings & Dosing

Read the Patient Information Leaflet if available from your pharmacist before you start taking levothyroxine and each time you get a refill. If you have any questions, ask your doctor or pharmacist.

Take this medication by mouth as directed by your doctor, usually once daily on an empty stomach, 30 minutes to 1 hour before breakfast. Take this medication with a full glass of water unless your doctor directs you otherwise.

If you are taking the capsule form of this medication, swallow it whole. Do not split, crush, or chew. People who cannot swallow the capsule whole (such as infants or small children) should use the tablet form of the medication.

For infants or children who cannot swallow whole tablets, crush the tablet and mix in 1 to 2 teaspoons (5 to 10 milliliters) of water, and give using a spoon or dropper right away. Do not prepare a supply in advance or mix the tablet in soy infant formula. Consult your pharmacist for more information.

Dosage is based on your age, weight, medical condition, laboratory test results, and response to treatment.

Use this medication regularly in order to get the most benefit from it. To help you remember, take it at the same time each day.

Do not stop taking this medication without first consulting with your doctor. Thyroid replacement treatment is usually taken for life.

There are different brands of levothyroxine available. Do not change brands without first consulting your doctor or pharmacist.

Certain medications (such as cholestyramine, colestipol, colesevelam, antacids, sucralfate, simethicone, iron, sodium polystyrene sulfonate, calcium supplements, orlistat, lanthanum, sevelamer, among others) can decrease the amount of thyroid hormone that is absorbed by your body. If you are taking any of these drugs, separate them from this medication by at least 4 hours.

Symptoms of low thyroid hormone levels include tiredness, muscle aches, constipation, dry skin, weight gain, slow heartbeat, or sensitivity to cold. Tell your doctor if your condition worsens or persists after several weeks of taking this medication.

Eltroxin – Uses, Side Effects, Interactions

How does this medication work? What will it do for me?

Levothyroxine is a thyroid hormone supplement used to treat people who do not produce enough thyroid hormone on their own. Levothyroxine helps to reduce the symptoms of low thyroid hormone such as weight gain, sensitivity to cold, lack of energy, and dry skin. It may take several weeks for this medication to have a noticeable effect on your condition.

This medication is also used to decrease the size of an enlarged thyroid gland, also known as goiter.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

50 µg
Each white, round, scored tablet engraved with “50” on one side contains 50 µg of levothyroxine. Nonmedicinal ingredients: acacia powder, cornstarch, lactose, and magnesium stearate.

100 µg
Each yellow, round, scored tablet engraved with “100” on one side contains 100 µg of levothyroxine. Nonmedicinal ingredients: acacia powder, colorcon yellow, cornstarch, lactose, and magnesium stearate.

150 µg
Each blue, round, scored tablet engraved with “150” on one side contains 150 µg of levothyroxine. Nonmedicinal ingredients: acacia powder, colorcon blue, cornstarch, lactose, and magnesium stearate.

200 µg
Each pink, round, scored tablet engraved with “200” on one side contains 200 µg of levothyroxine. Nonmedicinal ingredients: acacia powder, cornstarch, erythrosine, lactose, magnesium stearate.

How should I use this medication?

The dose of levothyroxine depends on how much of the hormone is needed to bring blood levels back to the normal range. This is determined by blood tests that are done in a laboratory. The starting dose will depend on your general physical condition and the severity and length of time that you have been experiencing symptoms of low thyroid hormone levels.

You should take this medication once a day at the same time every day to ensure a consistent effect. Ideally, it should be taken 30 minutes to 1 hour before eating breakfast, however it is most important that it be taken the same way every day. The dose of levothyroxine should be taken at least 4 hours before or after medications that change the way that levothyroxine is absorbed. Cotton seed meal, dietary fibre, soybean flour (infant formula), or walnuts may decrease the absorption of levothyroxine.

For infants or children who cannot swallow levothyroxine tablets, this medication may be crushed and added to a small amount (5 to 10 mL) of water, breast milk or non-soybean based formula. This mixture can then be given with a spoon or dropper. Tablets may also be crushed and sprinkled on a small amount of food like applesauce. Do not store crushed tablet mixtures for any period of time.

Signs that you may be getting too much thyroid hormone may include chest pain, increased heart rate, palpitations, excessive sweating, heat intolerance, and nervousness. If you think your dose of thyroid hormone may be too high, consult your doctor as soon as possible.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones given here, do not change the way that you are using the medication without consulting your doctor.

It is important to take this medication exactly as recommended by your doctor. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Store this medication at room temperature, protect it from light and moisture, and keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to levothyroxine or any ingredients of the medication
  • are having a heart attack
  • have acute thyrotoxicosis (too much thyroid hormone in their system)
  • have uncorrected adrenal insufficiency
  • are pregnant and are taking medications for an overactive thyroid

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • appetite changes
  • diarrhea
  • fever
  • hair loss (temporary; particularly in children during the first month of treatment)
  • headache
  • increased sweating
  • leg cramps
  • menstrual cycle changes
  • muscle weakness
  • nervousness or irritability
  • restlessness
  • sensitivity to heat
  • stomach cramps
  • tremor (shaking)
  • trouble sleeping
  • upset stomach
  • weight changes

Although most of these side effects listed below don’t happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • anxiety
  • joint pain, stiffness, or limping in children
  • mood swings
  • vomiting

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • fast, pounding, or irregular heartbeat
  • signs of a heart attack (e.g., crushing chest pain radiating down left arm or jaw, nausea, vomiting, sweating, or shortness of breath)
  • signs of heart problems (e.g., fast, pounding, or irregular heartbeat, shortness of breath, swelling of the legs and ankles)
  • signs of increased pressure in the brain (in children) (e.g., headaches, vision problems, ringing in the ears, arm pain)
  • seizures
  • severe allergic reaction (e.g., hives; difficulty breathing; wheezing; or swelling of the eyes, mouth, or lips)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Bone density: Levothyroxine can cause bones to lose thickness. If you have an increased risk for osteoporosis (bone thinning) or are taking medications that reduce bone thickness (e.g., prednisone or antiseizure medications), before you start taking this medication, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Your doctor may monitor your bone thickness while you are taking this medication.

Diabetes: Levothyroxine raises blood sugar levels. For people with diabetes, this may result in an increase in the requirements for insulin or antidiabetes medications. If you have diabetes or are at an increased risk of developing diabetes, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

You may need to monitor your blood sugar more closely when starting this medication or changing doses of this medication.

Heart disease: When starting levothyroxine, people with heart disease may be started on a lower dosage as it may cause the heart to work harder than it has been used to. If you have heart disease, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Seizures: Rarely, people taking levothyroxine have experienced seizures when they first start taking the medication. If you have a history of seizure disorder, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Signs of getting too much or too little medication: Contact your doctor as soon as possible if you notice any signs of getting too much medication (such as chest pain, confusion, fast or irregular heartbeat, mood swings, muscle weakness, psychosis, extreme restlessness, yellow eyes or skin, or shortness of breath) or signs of not getting enough medication (such as clumsiness, coldness, constipation, dry, puffy skin, listlessness, muscle aches, sleepiness, tiredness, weakness, or weight gain).

Weight loss: Levothyroxine should not be used for weight loss. Large doses of levothyroxine can cause serious or even life threatening side effects especially when taken together with other medications for weight loss.

Pregnancy: Levothyroxine should be taken throughout pregnancy to regulate the levels of thyroid hormone for the pregnant mother and the developing baby. If you become pregnant while taking this medication, contact your doctor as soon as possible. Your doctor may want to monitor your thyroid function more closely while you are pregnant.

Breast-feeding: Only a small amount of thyroid hormone is passed into breast milk. The use of appropriate amounts of this medication by breast-feeding women has not been shown to cause harm to breast-fed babies.

Seniors: Seniors may be more sensitive to the effects of levothyroxine.

What other drugs could interact with this medication?

There may be an interaction between levothyroxine and any of the following:

  • amiodarone
  • antacids (e.g., aluminum hydroxide, calcium carbonate, magnesium hydroxide)
  • anticonvulsants (e.g., carbamazepine, phenytoin, phenobarbital)
  • apalutamide
  • beta-blockers (e. g., metoprolol, propranolol)
  • birth control pills containing estrogen
  • calcium carbonate
  • calcium polystyrene sulfonate
  • cholestyramine
  • ciprofloxacin
  • colesevelam
  • colestipol
  • corticosteroids (e.g., dexamethasone, hydrocortisone, prednisone)
  • diabetes medications (e.g., glyburide, insulin, metformin, rosiglitazone)
  • diazepam
  • diet pills
  • digoxin
  • estrogens (e.g., conjugated estrogen, estradiol, ethinyl estradiol)
  • furosemide
  • heparin
  • iodide
  • iron supplements (e.g., ferrous fumarate, ferrous gluconate, ferrous sulfate)
  • lithium
  • magnesium supplements (e.g., magnesium hydroxide, magnesium oxide)
  • maprotiline
  • metoclopramide
  • methimazole
  • multivitamins/minerals with iron, folic acid.
  • nicotinic acid
  • non-steroidal anti-inflammatory medications (NSAIDs; e.g., diclofenac, ibuprofen, ketorolac, naproxen)
  • octreotide
  • orlistat
  • propylthiouracil
  • proton pump inhibitors (PPIs; e.g., esomeprazole, lansoprazole, omeprazole)
  • raloxifene
  • rifampin
  • selective serotonin reuptake inhibitors (SSRIs; e.g., citalopram, fluoxetine, paroxetine, sertraline)
  • semaglutide
  • sevelamer
  • simethicone
  • sodium polystyrene sulfonate
  • somatropin
  • certain statins (e.g., lovastatin, simvastatin)
  • sucralfate
  • testosterone
  • theophyllines (e.g., aminophylline, oxtriphylline, theophylline)
  • tamoxifen
  • thiazide diuretics (e.g., hydrochlorothiazide)
  • tricyclic antidepressants (e.g., amitriptyline, imipramine)
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications that you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.

All material copyright MediResource Inc. 1996 – 2021. Terms and conditions of use. The contents herein are for informational purposes only. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Source: www.medbroadcast.com/drug/getdrug/Eltroxin

Eltroxin 0.1mg (1000) – InhousePharmacy.vu


Product Name
Eltroxin 0.1mg 1000 Tablets/Pack

Active Ingredient
Levothyroxine – Synthetic T4


Product Type
Thyroid hormone (thyroxine)

Product expiry date we are currently shipping
Sep 2022

Eltroxin tablets 100mcg contain the thyroid hormone levothyroxine, and are used to replace the lack of thyroid hormone (thyroxine) caused by an underactive thyroid, to treat the symptoms of hypothyroidism.

Eltroxin general information

What is Eltroxin used for?

Eltroxin tablets 100mcg are used to treat hypothyroidism or underactive thyroid, a condition in which the thyroid gland does not make enough thyroid hormone (thyroxine) needed to regulate your body’s growth and metabolism. Hypothyroidism can be idiopathic (of unknown cause) or congenital as in the case of the autoimmune disease Hashimoto’s thyroiditis, where the thyroid gland is destroyed by the immune system. Eltroxin tablets 100mcg are a replacement hormone to relieve the symptoms of hypothyroidism, including, tiredness, muscle weakness, cramps, feeling the cold, a slow heart rate, dry and flaky skin, hair loss, a deep husky voice and weight gain. Eltroxin tablets 100mcg are also used to treat juvenile myxoedema, which is a clinical condition of swelling under the skin and thickening of the skin that occurs in children who are deficient in thyroid hormone, usually due to their mother having a nutritional deficiency in iodine while in the womb, and who are physically and mentally underdeveloped.

How does Eltroxin work?

Eltroxin tablets 100mcg contain levothyroxine, a synthetic thyroid hormone that is identical to the naturally occurring thyroid hormone thyroxine or T4, produced by the thyroid gland. Levothyroxine is converted to the more active form of thyroid hormone (T3) which interacts with a specific receptor inside cells to stimulate proteins needed to manage and regulate a variety of processes including how the body regulates temperature, metabolises nutrients and controls growth and development. Thyroxine regulates the production of another hormone called thyroid stimulating hormone (TSH) which in turn controls how much thyroxine is produced. Eltroxin tablets 100mcg regulate TSH production in the same way and therefore substitutes for a lack of endogenous thyroxine (produced by the thyroid gland).

What does Eltroxin contain?

Eltroxin tablets 100mcg contain the active ingredient levothyroxine, which replaces the lack of endogenous thyroxine (produced by the thyroid gland) to regulate normal growth and metabolism.

Treating underactive thyroid (hypothyroidism) with Eltroxin

Eltroxin tablets 100mcg contain levothyroxine, which is a synthetic thyroid hormone that is identical to the naturally occurring thyroid hormone thyroxine or T4 and substitutes for the lack of thyroid hormone in hypothyroidism (underactive thyroid gland) to regulate normal growth and metabolism. Eltroxin tablets 100mcg are used to treat idiopathic (of unknown cause) hypothyroidism or congenital hypothyroidism as in the case of the autoimmune disease Hashimoto’s thyroiditis, where the thyroid gland is destroyed by the immune system; also juvenile myxoedema, which is a clinical condition of swelling under the skin and thickening of the skin that occurs in children who are deficient in thyroid hormone, usually due to their mother having a nutritional deficiency in iodine while in the womb, and who are physically and mentally underdeveloped. Eltroxin tablets 100mcg help relieve symptoms of hypothyroidism, including, tiredness, muscle weakness, cramps, feeling the cold, a slow heart rate, dry and flaky skin, hair loss, a deep husky voice and weight gain.

What are the side effects of Eltroxin?

Most of the side effects experienced with taking Eltroxin tablets 100mcg mean that your dose is too high and may need adjusting. These include: headache, sleep problems (insomnia), feeling nervous or irritable sweating, flushing, appetite changes, weight loss, muscle weakness/cramps, tremors.

When should Eltroxin not be used?

You should not use Eltroxin tablets 100mcg if you:

  • are allergic to levothyroxine or any of the ingredients in Eltroxin tablets
  • are pregnant or planning to become pregnant
  • have had a heart attack, a thyroid disorder called thyrotoxicosis, or an adrenal gland problem that is not controlled by treatment
  • are a diabetic taking antidiabetics or insulin, without discussion with your doctor, as Eltroxin may affect your glucose tolerance
  • are taking other medications that may interact with Eltroxin, such as anticonvulsants like phenytoin and carbamazepine, cardiac glycosides like digoxin for heart failure, cholesterol-lowing drugs containing cholestyramine, tricyclic antidepressants, anticoagulants

What medications interact with Eltroxin?

Several medications interact with Eltroxin and should either not be taken while you are taking product name or only after discussion and instruction from your doctor:

  • Drugs that affect Eltroxin: the anticonvulsants phenytoin and carbamazepine, cholesterol-lowing drugs containing cholestyramine
  • Drugs that are affected by Eltroxin: anticoagulants , the anticonvulsant phenytoin , cardiac glycosides like digoxin for heart failure, tricyclic antidepressants

How should Eltroxin be taken?

You should take your Eltroxin tablets 100mcg once daily with water on an empty stomach, preferably 30 minutes before eating breakfast. Your doctor may increase your dose of Eltroxin tablets 100mcg, depending on your condition and response. Eltroxin tablets 100mcg are a long-term treatment and you should continue to take your Eltroxin tablets 100mcg regularly for as long as recommended by your doctor, which may be for and may be for the rest of your life.

How long should you take Eltroxin?

Eltroxin tablets 100mcg are a long-term treatment and you should continue to take your Eltroxin tablets 100mcg regularly for as long as recommended by your doctor, which may be for and may be for the rest of your life.

Missed dose of Eltroxin

If you miss a dose of Eltroxin tablets 100mcg take it as soon as you remember, unless it is time to take the next dose, then skip the missed dose. Do not take a double dose.

How should Eltroxin be stored?

You should keep your Eltroxin tablets 100mcg in the bottle until it is time to take one. Store in a cool dry place away from light where the temperature stays below 25°C.

Eltroxin 100mcg tablets – Summary of Product Characteristics (SmPC)

This information is intended for use by health professionals

Eltroxin 100mcg tablets

Levothyroxine 100mcg tablets

Each tablet contains 100 micrograms Levothyroxine sodium anhydrous.

Excipient with known effect

Lactose 48.86mg per tablet

For the full list of excipients, see section 6.1.


White, uncoated, biconvex tablets engraved on one face with “LT” and “100” on the other.

Recommended clinical indications: Control of hypothyroidism, congenital hypothyroidism in infants, acquired hypothyroidism in children and juvenile myxoedema.


In younger patients, and in the absence of heart disease, a serum Levothyroxine (T4) level of 70 to 160 nanomols per litre, or a serum thyrotrophin level of less that 5 milli-units per litre should be targeted. A pre-therapy ECG is valuable because ECG changes due to hypothyroidism may be confused with ECG evidence of cardiac ischaemia. If too rapid an increase in metabolism is produced (causing diarrhoea, nervousness, rapid pulse, insomnia, tremors, and sometimes anginal pain where there is latent cardiac ischaemia,) dosage must be reduced, or withheld, for a day or two, and then re-started at a lower dose level.


Initially 100 micrograms daily, preferably taken before breakfast or the first meal of the day. Adjust at three to four week intervals by 50 micrograms until normal metabolism is steadily maintained. The final daily dose may be up to 100 to 200 micrograms.


As for patients aged over 50 years.

For patients over 50 years, initially, it is not advisable to exceed 50 micrograms daily. In this condition, the daily dose may be increased by 50 micrograms at intervals of every 3-4 weeks, until stable thyroxine levels are attained. The final daily dose may be up to 50 to 200 micrograms.

Patients over 50 years with cardiac disease

Where there is cardiac disease, 25 micrograms daily or 50 micrograms on alternate days is more suitable. In this conditions, the daily dose may be increased by 25 micrograms at intervals of every 4 weeks, until stable thyroxine levels are attained. The final daily dose may be up to 50 to 200 micrograms.

For patients aged over 50 years, with or without cardiac disease, clinical response is probably a more acceptable criteria of dosage rather that serum levels.

Paediatric population

The maintenance dose is generally 100 to 150 micrograms per m2 body surface area. The dose for children depends on their age, weight and the condition being treated. Regular monitoring using serum TSH levels, as in adults, is required to make sure he/she gets the right dose. Infants should be given the total daily dose at least half an hour before the first meal of the day.

Congenital hypothyroidism in infants:

For neonates and infants with congenital hypothyroidism, where rapid replacement is important, the initial recommended dosage is 10 to 15 micrograms per kg BW per day for the first 3 months. Thereafter, the dose should be adjusted individually according to the clinical findings and thyroid hormone and TSH values.

Acquired hypothyroidism in children:

For children with acquired hypothyroidism, the initial recommended dosage is 12.5-50 micrograms per day. The dose should be increased gradually every 2 to 4 weeks according to the clinical findings and thyroid hormone and TSH values until the full replacement dose is reached.

Juvenile myxoedema in children:

The initial recommended dosage is 25 micrograms daily. In such conditions, the daily dose may be increased by 25 micrograms at intervals of every 2 – 4 weeks, until mild symptoms of hyperthyroidism is seen. The dose will then be reduced slightly.

In children under 5 years of age, the administration of whole tablets is not recommended. It is also not recommended that tablets are crushed and dispersed in water or other liquids, owing to limited solubility which could lead to dosing inaccuracy. In this age group it is preferable to administer an approved oral solution of levothyroxine.

Method of administration


• Hypersensitivity to the active substance or to any of the excipients listed in section 6.1.

• Thyrotoxicosis

• Adrenal gland disorder or adrenal insufficiency

Levothyroxine should be introduced very gradually in patients aged over 50 years (see section 4.2) and those with long standing hypothyroidism to avoid any sudden increase in metabolic demands.

Patients with panhypopituitarism or other causes predisposing to adrenal insufficiency may react to levothyroxine treatment, and it is advisable to start corticosteroid therapy before giving levothyroxine to such patients.

Levothyroxine sodium should be used with caution in patients with cardiovascular disorders, including angina, coronary artery disease, hypertension, and in the elderly who have a greater likelihood of occult cardiac disease.

To minimise the risk of adverse effects of undetected overtreatment, such as atrial fibrillation and fractures associated with low serum levels of thyroid stimulating hormone (TSH) in older patients, it is important to monitor serum TSH and adjust the dose accordingly during long term use.

In individuals suspected to have cardiovascular disease or to be at high risk, it is important to perform an ECG prior to commencement of levothyroxine treatment in order to detect changes consistent with ischaemia in which case, levothyroxine should be initiated at a low dose, followed by cautious dose escalation to avoid worsening of ischaemia or precipitation of an infarct.

Special care is needed for the elderly and for patients with symptoms of myocardial insufficiency, or ECG evidence of myocardial infarction.

Thyroid replacement therapy may cause an increase in dosage requirements of insulin or other anti-diabetic therapy (such as metformin). Care is needed for patients with diabetes mellitus, and diabetes insipidus.

See note above regarding withdrawal of treatment.

Subclinical hyperthyroidism may be associated with bone loss. To minimise the risk of osteoporosis, dosage of levothyroxine sodium should be titrated to the lowest possible effective level.

Parents of children receiving thyroid agent should be advised that partial loss of hair may occur during the first few months of therapy, but this effect is usually transient and subsequent regrowth usually occurs.

Care is required when levothyroxine is administered to patients with known history of epilepsy. Seizures have been reported rarely in association with the initiation of levothyroxine sodium therapy and may be related to the effect of thyroid hormone on seizure threshold.

Haemodynamic parameters should be monitored when levothyroxine therapy is initiated in very low birth weight preterm neonates as circulatory collapse may occur due to the immature adrenal function.

A small number of patients report adverse events on changing between different levothyroxine products. In some cases, symptoms are reported despite thyroid function tests within the reference range. If patients report side effects on switching between products, consider thyroid function testing. For patients who are persistently symptomatic after switching, whether they are biochemically euthyroid or have evidence of abnormal thyroid function, consider consistently prescribing a specific levothyroxine product that is well-tolerated by the patient. If symptoms or poor control of thyroid function persist despite adhering to a specific product, prescription of levothyroxine in an oral solution formulation should be considered.


Patients with rare hereditary problems of galactose intolerance, total lactase deficiency or glucose-galactose malabsorption should not take this medicine.

This medicine contains less than 1 mmol sodium (23 mg) per tablet, that is to say essentially ‘sodium-free’.

Interactions affecting other drugs:

Levothyroxine increases the effect of anticoagulants (Warfarin) and it may be necessary to reduce the anticoagulation dosage if excessive, hypoprothrombinaemia and bleeding are to be avoided.

Blood sugar levels are raised and dosage of anti-diabetic agents may require adjustment.

Tricyclic anti-depressants (e.g. amitriptyline, imipramine, dosulepin) response may be accelerated because levothyroxine increases sensitivity to catecholamines; concomitant use may precipitate cardiac arrhythmias.

The effects of sympathomimetic agents (e.g. adrenaline or phenylephrine) are also enhanced

Cardiac glycosides: If levothyroxine therapy is initiated in digitalised patients, the dose of digitalis may require adjustment. Hyperthyroid patients may need their digoxin dosage gradually increased as treatment proceeds because initially patients are relatively sensitive to digoxin.

NSAIDs: False low plasma concentrations have been observed with concurrent anti-inflammatory treatment such as phenylbutazone or acetylsalicylic acid and levothyroxine therapy.

Beta Blockers: levothyroxine (thyroxine) accelerates metabolism of propranolol, atenolol and sotalol.

General anaesthetics: Isolated reports of marked hypertension and tachycardia have been reported with concurrent ketamine administration.

Interactions affecting Levothyroxine:

Amiodarone may inhibit the de iodination of thyroxine to tri iodothyronine resulting in a decreased concentration of tri iodothyronine, thereby reducing the effects of thyroid hormones.

Anti-convulsants, such as carbamazepine and phenytoin, enhance the metabolism of thyroid hormones and may displace them from plasma proteins.

Initiation or discontinuation of anti-convulsant therapy may alter levothyroxine dosage requirements.

Effects of Levothyroxine may be decreased by concomitant sertraline.

Absorption of levothyroxine (thyroxine) possibly reduced by antacids, proton pump inhibitors, calcium salts, cimetidine, oral iron, sucralfate, colestipol, polystyrene sulphonate resin and cholestyramine (administration should be separated by 4-5 hours).

Metabolism of levothyroxine (thyroxine) accelerated by rifampicin, barbituarates, and primidone. (may increase requirements for levothyroxine (thyroxine) in hypothyroidism)

Imatinib: plasma concentration of levothyroxine (thyroxine) possibly reduced by imatinib.

Beta blockers may decrease the peripheral conversion of levothyroxine to triiodothyronine.

Lipid regulating drugs: Lovastatin has been reported to cause one case each of hypothyroidism and hyperthyroidism in two patients taking levothyroxine.

Sex Hormones: Oestrogen, oestrogen containing product (including hormone replacement therapy) and oral contraceptives may increase the requirement of thyroid therapy dosage. Conversely, androgens and corticosteroids may decrease serum concentrations of Levothyroxine-binding globulins.

Anti-obesity drugs such as orlistat may decrease levothyroxine absorption which may result in hypothyroidism (monitor for changes in thyroid function).

A number of drugs may affect thyroid function tests and this should be borne in mind when monitoring a patient on levothyroxine therapy.

Post-marketing cases have been reported indicating a potential interaction between ritonavir containing products and levothyroxine. Thyroid- stimulating hormone (TSH) should be monitored in patients treated with levothyroxine at least the first month after starting and /or ending ritonavir treatment.


The safety of Levothyroxine treatment during pregnancy is not known, but any possible risk of foetal abnormalities should be weighed against the risk to the foetus of untreated hypothyroidism.


Levothyroxine is excreted in breast milk in low concentrations, and it is contentious whether this can interfere with neonatal screening.


No data available

Levothyroxine has no or negligible influence on the ability to drive and use machines

Side-effects are usually indicative of excessive dosage and usually disappear on reduction of dosage or withdrawal of treatment for a few days.

Adverse reactions listed below have been observed during clinical studies and/or during marketed use and are based on clinical trial data and classified according to MedDRA System Organ Class. Frequency categories are defined according to the following convention:

Not known (cannot be estimated from the available data)

System organ class

Undesirable effects

Immune system disorders

Hypersensitivity reaction

Endocrine disorders

Thyrotoxic crisis1

Psychiatric disorders

Restlessness, agitation, insomnia

Nervous system disorders


Cardiac disorders

Angina pectoris, arrhythmia, palpitations, tachycardia

Vascular disorders


Respiratory, thoracic and mediastinal disorders


Gastrointestinal disorders

Diarrhoea, vomiting

Skin and subcutaneous tissue disorders

Hyperhidrosis, alopecia, rash, pruritus

Musculoskeletal and connective tissue disorder

Arthralgia, muscle spasm, muscular weakness

Reproductive system and breast disorders

Menstruation irregular

General disorders and administration site conditions

Headache, pyrexia, malaise, oedema


Weight decreased

1Some patients may experience a severe reaction to high levels of thyroid hormone. This is called a “thyroid crisis” with any of the following symptoms: Hyperpyrexia, tachycardia, arrhythmia, hypotension, cardiac failure, jaundice, confusion, seizure and coma

Paediatric population

Heat intolerance, transient hair loss, benign intracranial hypertension, craniostenosis in infants and premature closure of epiphysis in children.

Reporting of suspected adverse reactions

Reporting suspected adverse reactions after authorisation of the medicinal product is important. It allows continued monitoring of the benefit/risk balance of the medicinal product. Healthcare professionals are asked to report any suspected adverse reactions via the Yellow Card Scheme Website : www.mhra.gov.uk/yellowcard or search for MHRA Yellow Card in the Google Play or Apple App Store.


In most cases there will be no features. Signs of an overdose may include: fever, chest pain (angina), racing or irregular heartbeat, muscle cramps, headache, restlessness, flushing, sweating, diarrhoea, tremor, insomnia and hyperpyrexia. These signs can take up to 5 days to appear. Atrial fibrillation may develop. Convulsions occurred in one child. There may be increased toxicity in those with pre-existing heart disease.


Give oral activated charcoal if more than 10mg has been ingested by an adult or more than 5mg by a child, within 1 hour. If more than 10mg has been ingested by an adult or more than 5mg by a child, take blood 6-12 hours after ingestion for measurement of the free thyroxine concentration. The analysis does not need to be done urgently but can wait until the first working day after the incident. Patients with normal free thyroxine concentrations do not require follow up. Those with high concentrations should have outpatient review 3-6 days after ingestion to detect delayed onset hyperthyroidism. Features of clinical hyperthyroidism should be controlled with beta-blockers, e.g. propranolol.

Pharmacotherapeutic group: Thyroid hormones, ATC Code: H03AA01

Mechanism of action

Eltroxin is a tablet containing the hydrated form of Levothyroxine sodium which is used for the treatment of hypothyroidism. The thyroid gland is dependent upon 2 active principles for its main hormone activity these are Levothyroxine (tetraiodothyronine) and Tri-iodothyronine (see Goodman and Gilman, 1985). These closely related iodine containing amino acids are incorporated into the glycoprotein thyroglobulin. The chief action of these hormones is to increase the rate of cell metabolism. Levothyroxine is deiodinated in peripheral tissues to form Tri-iodothyronine which is thought to be the active tissue form of thyroid hormone.

Pharmacodynamic effects

Tri-iodothyronine is certainly more rapid acting and has a shorter duration of action than Levothyroxine.

The chief action of Levothyroxine is to increase the rate of cell metabolism


Levothyroxine sodium is incompletely and variably absorbed from the gastrointestinal tract.


It is almost completely bound to plasma proteins and has a half-life in the circulation of about a week in healthy subjects, but longer during pregnancy in patients with myxoedema.


A large portion of the Levothyroxine leaving the circulation is taken up by the liver. Part of a dose of Levothyroxine is metabolised to triiodothyronine.


Levothyroxine is excreted in the urine as free drug, deiodinated metabolites and conjugates. Some Levothyroxine is excreted in the faeces. There is limited placental transfer of Levothyroxine.

No further data of relevance.

Sodium Citrate BP

Lactose BP

Maize starch BP

Powdered acacia BP

Magnesium Stearate BP

24 months for polypropylene containers.

24 months for blister packs.

Do not store above 25°C. Store in the original package in order to protect from light and moisture.

Polypropylene container with tamper-evident low density polyethylene lid, containing 28, 56, 112, 100 or 1000 Eltroxin 100mcg tablets.

Blister packaging PVC/PVDC film (heat treated foil/heat seal lacquer) containing 28, 56 and 112 Eltroxin 100mcg tablets.

Not all pack sizes may be marketed.

No special requirements for disposal.

Any unused medicinal product or waste material should be disposed of in accordance with local requirements.

Mercury Pharma Group Ltd

Capital House, 85 King William Street,

London EC4N 7BL, UK

Eltroxin Tablets – NPS MedicineWise

What is in this leaflet

This leaflet answers some common questions about Eltroxin tablets.

It does not contain all the available information about the medicine.

It does not take the place of talking to your doctor or pharmacist.

All medicines have risks and benefits. Your doctor has weighed the risks of you taking Eltroxin against the benefits he or she expects it will have.

If you have any concerns about taking this medicine, ask your doctor or pharmacist.

Keep this leaflet with the medicine.

You may need to read it again.

The name of your medicine is Eltroxin. It is available in tablets of six different strengths: 25 micrograms (scored), 50 micrograms, 75 micrograms, 100 micrograms, 125 micrograms and 200 micrograms.

The active ingredient is called levothyroxine sodium.

What is it used for

Levothyroxine sodium is a thyroid hormone. It is used as replacement therapy in the treatment of thyroid hormone deficiency.

Eltroxin is used to treat:

  1. Thyroid hormone deficiency also known as Hypothyroidism.
    Hypothyroidism is a disease in which the thyroid gland is underactive and does not produce enough levothyroxine, a hormone, which is important for controlling your metabolism. Symptoms of hypothyroidism include tiredness, muscle weakness, and cramps, feeling the cold, a slow heart rate, dry and flaky skin, hair loss, a deep husky voice and weight gain.
  2. TSH-responsive tumours (certain tumours of the thyroid gland) of the thyroid
    For these conditions to be treated, patients need a supply of thyroid hormones in their body. Eltroxin replaces the shortage of thyroid hormones.

Use Eltroxin only as directed.

Your doctor may have prescribed Eltroxin for another condition.

Ask your doctor if you have any questions about why the medicine has been prescribed for you.

Ask your doctor if you have any concerns about taking it.

Eltroxin tablets are only available with a doctor’s prescription.

Before you take it

When you must not take it

Do not take Eltroxin if you are allergic to:

  • Levothyroxine sodium or any other thyroid hormone (eg. Tertroxin)
  • Any of the inactive ingredients listed at the end of this leaflet.

Some of the symptoms of an allergic reaction to Eltroxin may include red, itchy skin rashes, difficulty in breathing, swelling of the face or throat or faintness.

Do not use Eltroxin after the expiry date (EXP.) printed on the pack.

If you take the medicine after the expiry date has passed, it may not work as well.

Do not take the medicine if the packaging shows signs of tampering.

Before you start to take it

Tell your doctor if:

  1. You are allergic to any other medicines or any foods, dyes or preservatives.
  2. You are pregnant or intend to become pregnant.
    Levothyroxine levels will need to be watched carefully during pregnancy. Your dosage of Eltroxin may need to be increased while you are pregnant.
    Ask your doctor about the risks and benefits of taking Eltroxin during pregnancy.
  3. You are breastfeeding or intend to breastfeed.
    Although small amounts of Eltroxin are found in breast milk, women who are breastfeeding should continue treatment with Eltroxin.
  4. You have or have had any other medical conditions/ health problems, including:
  • Overactive thyroid gland
  • Adrenal gland problem
  • Hyperthyroidism
  • Heart problems such as cardiovascular disorder
  • High blood pressure
  • Diabetes
  • Long-standing hypothyroidism, an underactive thyroid gland
  • Problems absorbing nutrients from the gastrointestinal tract

If you have not told your doctor about any of the above, tell them before you start to take any Eltroxin.

Taking other medicines

Tell your doctor if you are taking any other medicines, including medicines that you buy without a prescription from a pharmacy, supermarket or health food shop.

Some of these medicines may interfere with Eltroxin. These include:

  • Anticoagulants, medicines used to thin your blood (eg. Warfarin)
  • Antidepressants, medicines used to treat depression (e.g. Lithium, SSRIs, Tricyclic antidepressants)
  • Antivirals, medicines used to treat HIV/AIDS infection (e.g. ritonavir)
  • Antimalarials, medicines used to treat and prevent malaria (e.g. chloroquine and proguanil)
  • Medicines used to treat diabetes (e.g. insulin)
  • Beta-blockers, medicines used to treat high blood pressure and heart conditions (e.g. propranolol)
  • Ion-exchange resins, medicines used to decrease cholesterol in the blood (e.g. cholestyramine)
  • Corticosteroids, antiinflammatory medicines (e.g. prednisolone and dexamethasone)
  • Oral contraceptives and hormone replacement medicines such as oestrogens, androgens or anabolic steroids
  • Medicines used for epilepsy (e.g. phenytoin and carbamazepine)
  • Medicines used to treat heart failure (e.g. digoxin)
  • Iron supplements
  • Calcium, magnesium and aluminiumsupplements
  • Rifampicin, an antibiotic used to treat tuberculosis and other serious infections
  • Ciprofloxacin, an antibiotic used to treat various infections
  • Soyabean flour (e.g. some infant formula and other products)
  • Antacids (e.g. aluminium hydroxide, magnesium hydroxide and calcium carbonate) and proton pump inhibitors, used to reduce stomach acid
  • Amiodarone, a medicine used to treat irregular heart beat
  • Oral contrast agents, used before X-ray and scans
  • Propylthiouracil, a medicine used to treat overactive thyroid and Graves disease
  • Non-steroidal anti-inflammatory drugs (NSAIDs), medicines used to relieve pain and/or inflammatory conditions including arthritis.
  • Weight loss drugs (e.g. orlistat)

These medicines may affect how well Eltroxin works, or react with it resulting in unwanted or sometimes serious side effects.

This list is not exhaustive. Your doctor or pharmacist has more information on medicines to be careful with or avoid while taking it.

Before you start to take any other medicine, tell your doctor or pharmacist that you are taking Eltroxin.

How to take it

Your doctor will decide on the right dose for you.

It may take a few weeks for Eltroxin to begin working. Until it begins working you may not notice any change in your symptoms.

Follow your doctor’s instructions carefully, as they may differ from the information contained in this leaflet.

How much to take

The usual starting dose for adults is 50 to 100 micrograms daily. The dose may be increased over time. The average adult maintenance dose is 100 to 200 micrograms. Lower doses are used in the elderly and children. Your doctor will calculate the dose required for you.

Your doctor will monitor your blood tests to make sure Eltroxin is working for you.

Carefully follow the dosage instructions, as given by your doctor.

Do not change your dose unless your doctor tells you to do so.

Talk to your doctor if you have any further questions.

How to take it

Swallow Eltroxin tablets with a glass of water.

When to take it

Eltroxin tablets should be taken first thing in the morning on an empty stomach, at least 30 minutes and preferably 60 minutes before any food or other medications .

How long to take it

Continue taking it as long as your doctor recommends it.

If you forget to take it

If it is almost time for your next dose, skip the dose you missed and take your next dose when you are meant to.

Otherwise, take your dose as soon as you remember, and then go back to taking it as you would normally.

Do not take a double dose to make up for the dose that you missed.

If you are unsure about whether to take your next dose, speak to your doctor or pharmacist.

If you have trouble remembering when to take your medicine, ask your pharmacist for some hints.

If you take too much (Overdose)

Immediately telephone your doctor or Poisons Information Centre (telephone 13 11 26) for advice, or go to Accident and Emergency at your nearest hospital, if you think that you or anyone else may have taken too much Eltroxin. Do this even if there are no signs of discomfort or poisoning.

If you take too much you may have the following symptoms: restlessness; vomiting; flushing; breathing difficulties; chest pain; convulsions or paralysis.

Keep your doctor, pharmacist, Accident and Emergency phone numbers handy.

While you are taking it

Things you must do

Do not switch or interchange with other brands unless advised by your doctor.

Immediately stop taking Eltroxin if a skin rash or other allergic reaction occurs.

Use it exactly as directed or as your doctor has prescribed.

Tell your doctor if you feel Eltroxin is not helping your condition.

Visit your doctor regularly. Your doctor needs to check your progress.

Tell any other doctors, dentists and pharmacists who are treating you that you are using Eltroxin.

Always discuss with your doctor any problems or difficulties during or after taking it.

If you plan to have surgery, tell your doctor or dentist that you are taking Eltroxin.

If you are about to start taking any new medicines, remind your doctor and pharmacist that you are taking Eltroxin.

Ensure you do not run out of medicine over the weekend or on holidays.

Things you must not do

Do not drive or operate machinery where alertness is required, until you know how the medicine affects you.

Do not give this medicine to anyone else, even if his or her symptoms seem similar to yours.

Side effects

Do not be alarmed by this list of possible side effects.

You may not experience any of them.

Tell your doctor or pharmacist as soon as possible if you do not feel well while you are taking it.

Tell your doctor or pharmacist if you notice any of the following and they worry you:

  • nervousness
  • anxiousness
  • excitation
  • restlessness
  • muscle weakness & cramps
  • inability to sleep
  • sleep disturbances
  • unusual movements, including tremor
  • headache
  • lack of concentration
  • diarrhoea
  • stomach cramp
  • nausea
  • vomiting
  • heat intolerance
  • excessive sweating
  • flushing
  • weight loss
  • menstrual irregularities
  • decreased libido
  • fever
  • shortness of breath
  • rapid breathing
  • irregular heart beats
  • chest pain
  • increased blood pressure
  • allergic reactions such as skin rash
  • hair loss
  • irritability
  • increased appetite
  • tiredness

Some people may get other side effects with Eltroxin.

Check with your doctor as soon as possible if you have any problems while taking it even if you do not think the problems are connected with this medicine or are not listed in this leaflet.

After using it


Store below 25°C.

Store in the original package. Keep the bottle tightly closed. Protect from light.

If you do not keep the tablets in the bottle they may not keep well.

Do not store Eltroxin, or any other medicines in a bathroom or near a sink. Do not leave it in the car or on windowsills.

Heat and dampness can destroy some medicines.

Do not take ELTROXIN tablets if the tablet’s colour has changed.

Keep the medicine out of reach of children.


If your doctor tells you to stop taking this medicine or it has passed its expiry date, ask your pharmacist what to do with any left over.

Product description

What it looks like

Eltroxin 25 microgram tablets are round, white, flat tablets marked with ‘25’ on one side and bisected on the other side.

Eltroxin 50 microgram tablets are round, white, flat tablets marked with ‘50’ on one side and ‘L01’ on the other side.

Eltroxin 75 microgram tablets are round, white, flat tablets marked with ‘75’ on one side and ‘L02’ on the other side.

Eltroxin 100 microgram tablets are round, white, flat tablets marked with ‘100’ on one side and ‘L10’ on the other side.

Eltroxin 125 microgram tablets are round, white, flat tablets marked with ‘125’ on one side and ‘L12’ on the other side.

Eltroxin 200 microgram tablets are round, white, flat tablets marked with ‘200’ on one side and ‘L21’ on the other side.

Eltroxin is available in bottles of 200 tablets.


Each Eltroxin tablet contains levothyroxine sodium as the active ingredient.

Each Eltroxin tablet contains the following excipients:

  • microcrystalline cellulose
  • maize starch
  • purified talc
  • colloidal anhydrous silica
  • magnesium stearate

They are free from gluten, sucrose, lactose and azo dyes.

Levothyroxine: Uses, Interactions, Mechanism of Action


Levothyroxine is a synthetic T4 hormone used to treat hypothyroidism that can be used along with surgery and radioiodine therapy to manage thyrotropin-dependent well-differentiated thyroid cancer.

Brand Names

Eltroxin, Euthyrox, Levo-T, Levothroid, Levoxyl, Np Thyroid, Synthroid, Thyquidity, Tirosint, Unithroid

Generic Name
DrugBank Accession Number

Levothyroxine is a synthetically produced form of thyroxine, a major endogenous hormone secreted by the thyroid gland.14 Also known as L-thyroxine or the brand name product Synthroid, levothyroxine is used primarily to treat hypothyroidism, a condition where the thyroid gland is no longer able to produce sufficient quantities of the thyroid hormones T4 (tetraiodothyronine or thyroxine) and T3 (triiodothyronine or Liothyronine), resulting in diminished down-stream effects of these hormones. Without sufficient quantities of circulating thyroid hormones, symptoms of hypothyroidism begin to develop such as fatigue, increased heart rate, depression4, dry skin and hair, muscle cramps, constipation, weight gain, memory impairment, and poor tolerance to cold temperatures.15,10

In response to Thyroid Stimulating Hormone (TSH) release by the pituitary gland, a normally functioning thyroid gland will produce and secrete T4, which is then converted through deiodination (by type I or type II 5′-deiodinases)8 into its active metabolite T3. While T4 is the major product secreted by the thyroid gland, T3 exerts the majority of the physiological effects of the thyroid hormones; T4 and T3 have a relative potency of ~1:4 (T4:T3).14 T4 and T3 act on nearly every cell of the body, but have a particularly strong effect on the cardiac system.6 As a result, many cardiac functions including heart rate, cardiac output, and systemic vascular resistance are closely linked to thyroid status.7

Prior to the development of levothyroxine, Thyroid, porcine or desiccated thyroid, used to be the mainstay of treatment for hypothyroidism. However, this is no longer recommended for the majority of patients due to several clinical concerns including limited controlled trials supporting its use. Desiccated thyroid products contain a ratio of T4 to T3 of 4.2:1, which is significantly lower than the 14:1 ratio of secretion by the human thyroid gland. This higher proportion of T3 in desiccated thyroid products can lead to supraphysiologic levels of T3 which may put patients at risk of thyrotoxicosis if thyroid extract therapy is not adjusted according to the serum TSH.10,15

Small Molecule
Average: 776.87
Monoisotopic: 776.686681525
Chemical Formula
  • 3,3′,5,5′-Tetraiodo-L-thyronine
  • 3,5,3′,5′-Tetraiodo-L-thyronine
  • 4-(4-Hydroxy-3,5-diiodophenoxy)-3,5-diiodo-L-phenylalanine
  • L-T4
  • L-Thyroxine
  • Levothyroxin
  • LT4
  • O-(4-Hydroxy-3,5-diidophenyl)-3,5-diiodo-L-tyrosine
  • O-(4-Hydroxy-3,5-diiodophenyl)-3,5-diiodo-L-tyrosine
  • T4
  • Thyroxine

Levothyroxine is indicated as replacement therapy in primary (thyroidal), secondary (pituitary) and tertiary (hypothalamic) congenital or acquired hypothyroidism. It is also indicated as an adjunct to surgery and radioiodine therapy in the management of thyrotropin-dependent well-differentiated thyroid cancer.

Reduce drug development failure rates

Build, train, & validate machine-learning modelswith evidence-based and structured datasets.

Build, train, & validate predictive machine-learning models with structured datasets.

Associated Conditions
Contraindications & Blackbox Warnings

Avoid life-threatening adverse drug events

Improve clinical decision support with information on contraindications & blackbox warnings, population restrictions, harmful risks, & more.

Avoid life-threatening adverse drug events & improve clinical decision support.


Oral levothyroxine is a synthetic hormone that exerts the same physiologic effect as endogenous T4, thereby maintaining normal T4 levels when a deficiency is present.

Levothyroxine has a narrow therapeutic index and is titrated to maintain a euthyroid state with TSH (thyroid stimulating hormone) within a therapeutic range of 0.4–4.0 mIU/L.10 Over- or under-treatment with levothyroxine may have negative effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, emotional state, gastrointestinal function and glucose and lipid metabolism. The dose of levothyroxine should be titrated slowly and carefully and patients should be monitored for their response to titration to avoid these effects. TSH levels should be monitored at least yearly to avoid over-treating with levothyroxine which can result in hyperthyroidism (TSH 15

As many cardiac functions including heart rate, cardiac output, and systemic vascular resistance are closely linked to thyroid status,7 over-treatment with levothyroxine may result in increases in heart rate, cardiac wall thickness, and cardiac contractility and may precipitate angina or arrhythmias, particularly in patients with cardiovascular disease and in elderly patients. In populations with any cardiac concerns, levothyroxine should be initiated at lower doses than those recommended in younger individuals or in patients without cardiac disease. Patients receiving concomitant levothyroxine and sympathomimetic agents should be monitored for signs and symptoms of coronary insufficiency. If cardiac symptoms develop or worsen, reduce the levothyroxine dose or withhold for one week and restart at a lower dose.15

Increased bone resorption and decreased bone mineral density may occur as a result of levothyroxine over-replacement, particularly in post-menopausal women. The increased bone resorption may be associated with increased serum levels and urinary excretion of calcium and phosphorous, elevations in bone alkaline phosphatase and suppressed serum parathyroid hormone levels. Administer the minimum dose of levothyroxine that achieves the desired clinical and biochemical response to mitigate this risk.

Addition of levothyroxine therapy in patients with diabetes mellitus may worsen glycemic control and result in increased antidiabetic agent or insulin requirements. Carefully monitor glycemic control after starting, changing or discontinuing levothyroxine.

Mechanism of action

Levothyroxine is a synthetically prepared levo-isomer of the thyroid hormone thyroxine (T4, a tetra-iodinated tyrosine derivative) that acts as a replacement in deficiency syndromes such as hypothyroidism. T4 is the major hormone secreted from the thyroid gland and is chemically identical to the naturally secreted T4: it increases metabolic rate, decreases thyroid-stimulating hormone (TSH) production from the anterior lobe of the pituitary gland, and, in peripheral tissues, is converted to T3. Thyroxine is released from its precursor protein thyroglobulin through proteolysis and secreted into the blood where is it then peripherally deiodinated to form triiodothyronine (T3) which exerts a broad spectrum of stimulatory effects on cell metabolism. T4 and T3 have a relative potency of ~1:4.

Thyroid hormone increases the metabolic rate of cells of all tissues in the body. In the fetus and newborn, thyroid hormone is important for the growth and development of all tissues including bones and the brain. In adults, thyroid hormone helps to maintain brain function, food metabolism, and body temperature, among other effects. The symptoms of thyroid deficiency relieved by levothyroxine include slow speech, lack of energy, weight gain, hair loss, dry thick skin and unusual sensitivity to cold.

The thyroid hormones have been shown to exert both genomic and non-genomic effects.9 They exert their genomic effects by diffusing into the cell nucleus and binding to thyroid hormone receptors in DNA regions called thyroid hormone response elements (TREs) near genes.2 This complex of T4, T3, DNA, and other coregulatory proteins causes a conformational change and a resulting shift in transcriptional regulation of nearby genes, synthesis of messenger RNA, and cytoplasmic protein production.2,6 For example, in cardiac tissues T3 has been shown to regulate the genes for α- and β-myosin heavy chains, production of the sarcoplasmic reticulum proteins calcium-activated ATPase (Ca2+-ATPase) and phospholamban, β-adrenergic receptors, guanine-nucleotide regulatory proteins, and adenylyl cyclase types V and VI as well as several plasma-membrane ion transporters, such as Na+/K+–ATPase, Na+/Ca2+ exchanger, and voltage-gated potassium channels, including Kv1.5, Kv4.2, and Kv4.3. 7 As a result, many cardiac functions including heart rate, cardiac output, and systemic vascular resistance are closely linked to thyroid status.

The non-genomic actions of the thyroid hormones have been shown to occur through binding to a plasma membrane receptor integrin aVb3 at the Arg-Gly-Asp recognition site.12 From the cell-surface, T4 binding to integrin results in down-stream effects including activation of mitogen-activated protein kinase (MAPK; ERK1/2) and causes subsequent effects on cellular/nuclear events including angiogenesis and tumor cell proliferation.6,11


Absorption of orally administered T4 from the gastrointestinal tract ranges from 40% to 80% with the majority of the levothyroxine dose absorbed from the jejunum and upper ileum. T4 absorption is increased by fasting, and decreased in malabsorption syndromes and by certain foods such as soybeans, milk, and dietary fiber. Absorption may also decrease with age. In addition, many drugs affect T4 absorption including bile acide sequestrants, sucralfate, proton pump inhibitors, and minerals such as calcium (including in yogurt and milk products)3, magnesium, iron, and aluminum supplements. To prevent the formation of insoluble chelates, levothyroxine should generally be taken on an empty stomach at least 2 hours before a meal and separated by at least 4 hours from any interacting agents.

Volume of distribution

Not Available

Protein binding

Circulating thyroid hormones are greater than 99% bound to plasma proteins, including thyroxine-binding globulin (TBG), thyroxine-binding prealbumin (TBPA) and albumin (TBA). The higher affinity of both TBG and TBPA for T4 partially explains the higher serum levels, slower metabolic clearance and longer half-life of T4 compared to T3. Protein-bound thyroid hormones exist in reverse equilibrium with small amounts of free hormone where only unbound hormone is metabolically active.15


Approximately 70% of secreted T4 is deiodinated to equal amounts of T3 and reverse triiodothyronine (rT3), which is calorigenically inactive. T4 is slowly eliminated through its major metabolic pathway to T3 via sequential deiodination, where approximately 80% of circulating T3 is derived from peripheral T4. The liver is the major site of degradation for both T4 and T3, with T4 deiodination also occurring at a number of additional sites, including the kidney and other tissues.

Elimination of T4 and T3 involves hepatic conjugation to glucuronic and sulfuric acids. The hormones undergo enterohepatic circulation as conjugates are hydrolyzed in the intestine and reabsorbed. Conjugated compounds that reach the colon are hydrolyzed and eliminated as free compounds in the feces. Other minor T4 metabolites have been identified. 15

Hover over products below to view reaction partners

Route of elimination

Thyroid hormones are primarily eliminated by the kidneys. A portion of the conjugated hormone reaches the colon unchanged and is eliminated in the feces. Approximately 20% of T4 is eliminated in the stool. Urinary excretion of T4 decreases with age.15


T4 half-life is 6 to 7 days. T3 half-life is 1 to 2 days.15


Not Available

Adverse Effects

Improve decision support & research outcomes

With structured adverse effects data, including: blackbox warnings, adverse reactions, warning & precautions, & incidence rates.

Improve decision support & research outcomes with our structured adverse effects data.


LD50=20 mg/kg (orally in rat). Hypermetabolic state indistinguishable from thyrotoxicosis of endogenous origin. Symptoms of thyrotoxicosis include weight loss, increased appetite, palpitations, nervousness, diarrhea, abdominal cramps, sweating, tachycardia, increased pulse and blood pressure, cardiac arrhythmias, tremors, insomnia, heat intolerance, fever, and menstrual irregularities.

Pharmacogenomic Effects/ADRs
Not Available

Levothyroxine (Oral Route) Side Effects

Side Effects

Drug information provided by: IBM Micromedex

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur:

Less common

  1. Chest pain or discomfort

  2. decreased urine output

  3. difficult or labored breathing

  4. difficulty with swallowing

  5. dilated neck veins

  6. extreme fatigue

  7. fainting

  8. fast, slow, irregular, pounding, or racing heartbeat or pulse

  9. fever

  10. heat intolerance

  11. hives or welts, skin itching, rash, or redness

  12. irregular breathing

  13. irritability

  14. menstrual changes

  15. nausea

  16. pain or discomfort in the arms, jaw, back, or neck

  17. sweating

  18. swelling of the eyes, face, lips, throat, or tongue

  19. tightness in the chest

  20. tremors

  1. Blurred or double vision

  2. dizziness

  3. eye pain

  4. lack or slowing of normal growth in children

  5. limp or walk favoring one leg

  6. pain in the hip or knee

  7. seizures

  8. severe headache

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose

  1. Change in consciousness

  2. cold, clammy skin

  3. confusion

  4. disorientation

  5. fast or weak pulse

  6. lightheadedness

  7. loss of consciousness

  8. sudden headache

  9. sudden loss of coordination

  10. sudden slurring of speech

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

Less common

  1. Abdominal or stomach cramps

  2. change in appetite

  3. crying

  4. diarrhea

  5. false or unusual sense of well-being

  6. fear or nervousness

  7. feeling not well or unhappy

  8. feeling of discomfort

  9. feeling of warmth

  10. feeling things are not real

  11. feelings of suspicion and distrust

  12. hair loss

  13. headache

  14. increased appetite

  15. mental depression

  16. muscle weakness

  17. quick to react or overreact emotionally

  18. rapidly changing moods

  19. redness of the face, neck, arms, and occasionally, upper chest

  20. restlessness

  21. trouble getting pregnant

  22. trouble sitting still

  23. unusual tiredness or weakness

  24. vomiting

  25. weight gain or loss

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Portions of this document last updated: Aug. 01, 2021

Copyright © 2021 IBM Watson Health. All rights reserved. Information is for End User’s use only and may not be sold, redistributed or otherwise used for commercial purposes.


Thyroid hormones | Dopinglinkki

As amended on 16.09.2019

Properties and mechanism of action

Two metabolic active hormones are formed in the thyroid gland: tetraiodothyronine (thyroxine, T4) and triiodothyronine (T3). Thyroxine is converted to T3 (mainly in the liver and kidneys), which has more pronounced effects.

Thyroid hormones play an important role in the regulation of normal growth, development, metabolism, body temperature and blood flow.They affect the metabolism of fats, proteins and carbohydrates, the regulation of body temperature, and the maintenance of water and electrolyte balance.

Lack of thyroid hormones (eg, underactive thyroid gland or hypothyroidism) leads to a slowdown in metabolism, growth and development. T4 (levothyroxine) is a prescription drug used to treat hypothyroidism. The dose is selected individually.

Excessive levels of thyroid hormones lead to an acceleration of metabolism (weight loss), agitation, mental imbalance and sometimes to cardiac arrhythmias.For example, an excess effect can occur if a healthy person takes a drug that contains a thyroid hormone, or if the dose of the drug in a patient with hypothyroidism is increased too quickly.

Medical application and dosage

Thyroxin is mainly used for the treatment of hypothyroidism, that is, an insufficient functioning of the thyroid gland. The typical maintenance dose for adults is 0.1 mg / day. orally. However, treatment should be started with a lower dose (0.025–0.05 mg / day).The dose is gradually increased to the required maintenance dose [1].

Doping use

Thyroid hormone has a number of mechanisms that may be helpful in improving physical performance and motivating the use of thyroid hormone as a doping agent. These include increased basal metabolism and increased tissue sensitivity to catecholamines (adrenaline, norepinephrine, dopamine), which leads, in particular, to an increase in heart rate.Thyroid hormone also has a synergistic effect on growth hormone, enhancing its action [2].

There is evidence of the use of thyroid hormones in professional bodybuilders and amateur bodybuilders. They are aimed at changing body composition by accelerating metabolism and burning fat in the body [3, 4, 5]. In 2019, the thyroid hormone is not yet included in the WADA (World Anti-Doping Agency) Prohibited List [6]. However, cases of abuse do occur and various parties, including the Netherlands Anti-Doping Agency, are pushing for the addition of thyroid hormone to the banned list [7].The Finnish Penal Code also does not classify thyroid hormone as a doping drug.

Side effects

In patients with hypothyroidism, thyroid hormone preparations have a predominantly positive effect, if the dose is not increased too quickly and is not excessive. Excessive doses of drugs can lead to symptoms that resemble those of hyperthyroidism, including palpitations, arrhythmias, diarrhea, exhaustion, decreased tolerance to temperature fluctuations, insomnia, agitation, and even psychosis [8, 9].

For people with latent heart diseases, side effects of drugs on the heart (arrhythmias, myocardial infarction) can be extremely dangerous [10]. Before starting thyroid therapy, the physician should carefully assess the patient’s health, including an assessment of heart function. In this way, the risks associated with this therapy can be identified.

Long-term thyroxine overdose increases the risk of osteoporosis. In 0.1–0.5% of patients, a dangerous complication develops – agranulocytosis (a decrease in the level of leukocytes) [11].An acute overdose of thyroxine leads to the development of thyrotoxicosis, the symptoms of which are an increase in body temperature, impaired heart function and coma [12]. An overdose of thyroid hormones can be fatal. In these cases, the thyroid hormone was usually used together with other doping drugs [13].

Most common trade names (9/2014): Unithroid, L-Thyroxin, Levo-T, Levolet, Levoxyl, Novothyrox.

Timo Seppälä ( Timo Seppälä)

Head of Medical Facility
FINADA Finnish Anti-Doping Committee (now SUEK ry)

Amendments made: Dopinglinkki

instructions for use, analogs, composition, indications

The use of tricyclic antidepressants with levothyroxine sodium can lead to an increase in the effect of antidepressants.

Levothyroxine sodium reduces the action of cardiac glycosides.

With the simultaneous use of colestyramine and colestipol (ion exchange resins), as well as aluminum hydroxide, they reduce the plasma concentration of sodium levothyroxine by inhibiting its absorption in the intestine. In this regard, levothyroxine sodium should be used 4-5 hours before taking these drugs.

With simultaneous use with anabolic steroids, asparaginase, tamoxifen, pharmacokinetic interaction is possible at the level of binding to plasma proteins.

Protease inhibitors (eg, ritonavir, indinavir, lopinavir) may interfere with the effectiveness of levothyroxine sodium. Careful monitoring of thyroid hormone concentrations is recommended. If necessary, the dose of levothyroxine sodium should be adjusted.

Phenytoin can affect the effectiveness of levothyroxine sodium due to the displacement of levothyroxine sodium from the bond with plasma proteins, which can lead to an increase in the concentration of free T4 and T3.On the other hand, phenytoin increases the metabolic rate of levothyroxine sodium in the liver. Careful monitoring of thyroid hormone concentrations is recommended.

Levothyroxine sodium can reduce the effectiveness of hypoglycemic drugs. Therefore, frequent monitoring of blood glucose concentration is necessary from the moment of initiation of thyroid hormone replacement therapy. If necessary, the dose of the hypoglycemic drug should be adjusted.

Levothyroxine sodium can enhance the effect of anticoagulants (coumarin derivatives) by displacing them from the connection with plasma proteins, which can increase the risk of bleeding, for example, hemorrhage in the central nervous system or gastrointestinal bleeding, especially in elderly patients.Therefore, regular monitoring of coagulation parameters is necessary both at the beginning and during combination therapy with these drugs. If necessary, the dose of the anticoagulant should be adjusted.

Salicylates, dicumarol, furosemide in high doses (250 mg), clofibrate and other drugs can displace levothyroxine sodium from its connection with plasma proteins, which leads to an increase in the concentration of the free T4 fraction.

Sevelamer may decrease the absorption of levothyroxine sodium.

Tyrosine kinase inhibitors (eg, imatinib, sunitinib) can reduce the effectiveness of levothyroxine sodium. Therefore, at the beginning or at the end of the course of concomitant therapy with these drugs, it is recommended to monitor changes in thyroid function in patients. If necessary, the dose of levothyroxine sodium is adjusted.

Aluminum-containing drugs (antacids, sucralfate), iron-containing drugs, calcium carbonate are described in the literature as potentially reducing the effectiveness of levothyroxine sodium.Therefore, it is recommended to take levothyroxine sodium at least 2 hours before using these drugs.

Somatropin, when used simultaneously with sodium levothyroxine, can accelerate the closure of the epiphyseal growth zones.

Propylthiouracil, glucocorticosteroids, beta-sympatholytics, iodine-containing contrast agents, and amiodarone inhibit the peripheral conversion of T4 to T3. Due to the high iodine content, the use of amiodarone may be accompanied by the development of both hyperthyroidism and hypothyroidism.Particular attention should be paid to the nodular goiter with the possible development of unrecognized functional autonomy. Sertraline, chloroquine / proguanil decrease the effectiveness of levothyroxine sodium and increase serum TSH concentration.

Medicines that promote the induction of hepatic enzymes (eg, barbiturates, carbamazepine) can promote hepatic clearance of levothyroxine sodium.

In women using estrogen-containing contraceptives, or in postmenopausal women receiving hormone replacement therapy, the need for levothyroxine sodium may increase.

The use of soy-containing products can help reduce the absorption of levothyroxine sodium in the intestine. Therefore, dose adjustment may be required, especially at the beginning or after stopping the use of foods containing soy.

tyrosine – useful properties, use of amino acid

L tyrosine is an optically isomeric form of the aromatic amino acid tyrosine.The substance is involved in lipid metabolism, regulates appetite, improves melanin synthesis, normalizes the work of the adrenal glands, pituitary gland, and thyroid gland.

The amino acid L tyrosine belongs to the nonessential, as it is produced in the body. The deficiency is partially compensated for with protein foods. The compound was first discovered in cheese by the German scientist Liebig. Tyrosine is needed to build protein molecules in all tissues, is part of enzymes, and can partially replace molecular cross-links with a lack of other substances in the body.

Synthesis and role in the body

For the formation of tyrosine, phenylalanine is necessary – an essential amino acid, without which synthesis is impossible. Phenylalanine is needed for the structure of protein compounds, and all of its unused residue is converted into tyrosine. Thus, with a deficiency of a precursor substance, a tyrosine deficiency occurs.

With the participation of L tyrosine, hormones are produced in the adrenal glands and the thyroid gland.During enzymatic transformation, the production of skin and hair pigment – melanin occurs.

The adrenal glands, under the influence of tyrosine, produce hormones of the catecholamine group: adrenaline, norepinephrine, dopamine. These are neurotransmitters that control the work of the nervous system, stimulate the brain, and improve the transmission of nerve impulses. With increasing physical activity, the production of catecholamines increases, this allows the body to adapt. The faster the endocrine system reacts to stress, releasing the necessary substances into the blood, the easier it is for the cardiovascular system and muscles:

  • Adrenaline – produced with severe stress or sudden physical impulses.This increases the permeability of the cell walls, accelerates the breakdown of fats and carbohydrates to obtain more energy. The body’s endurance increases during this period.

  • Norepinephrine is secreted during moments of aggression, stress, prolonged hard physical work, and injuries. Strengthens muscle endurance, constricts blood vessels.

  • Dopamine – improves the absorption of glucose in tissues, stimulates cellular nutrition, constricts blood vessels, and causes a feeling of pleasure.Takes part in the formation of growth hormone.

In the thyroid gland, tyrosine is necessary for the synthesis of thyroid hormones – thyroxine and triiodothyronine. These are iodized amino acids necessary for normal growth and development of tissues, normal mental activity, regulation of metabolism and maintenance of normal body temperature. Substances of this group increase the body’s sensitivity to adrenal hormones.

Influence on body systems

The normalization of the concentration of L tyrosine affects the functioning of all body systems:

  • Cardiovascular.The compound helps to regulate blood pressure, reduces the risk of hypertension, improves vascular tone, and nutrition at the cellular level. The frequency and intensity of vegetative-vascular spasms decreases, the heart muscle is strengthened.

  • Nervous. L tyrosine enhances adaptability to psychological and physical stress, stimulates brain function, increases concentration, and helps fight depression and the effects of stress.

  • Endocrine.With the participation of tyrosine, hormones are synthesized in the thyroid gland, adrenal glands, pituitary gland, gonads in men and women. Their normal work supports cognitive, motor functions, regulates metabolism, helps to form the correct immune response to different types of pathogens.

  • Metabolism. Under the action of the substance, the breakdown of fats increases and carbohydrate metabolism is normalized. This leads to a decrease in appetite and utilization of lipid deposits.

An excess of tyrosine leads to dramatic weight loss, insomnia, distracted attention, increased excitability. This condition is associated with an increased concentration of thyroid hormones and requires correction.

The daily minimum requirement of an adult is 60 mg, and at high loads, severe decompensation or in a stressful situation, the consumption can increase to 4 g.

Consequences of a deficit of

An insufficient concentration of L tyrosine can lead to a decrease in concentration, loss of stamina, apathy, and with prolonged deficiency, there are:

  • Puffiness, drowsiness, dry skin, pallor, excess weight gain.This increases the risk of atherosclerosis, hypertension.

  • Disruption of the liver, kidneys. At the first stage, glucose ceases to be absorbed, cells lack nutrition, and the work of the excretory system is inhibited.

Food Sources

Despite the fact that L tyrosine is synthesized by our body with the participation of phenylalanine, most often this amount is not enough for the normal functioning of all systems.Eating foods such as:

  • Pork, beef, lamb.

  • Chicken, turkey, duck.

  • Fish and seafood.

  • Cheese, cottage cheese, yoghurts, kefir.

  • Nuts, sunflower seeds, sesame seeds, legumes.

In addition to food sources, you can compensate for the lack of L tyrosine by taking food supplements in the form of capsules, tablets, lozenges.

BAA with tyrosine

These are balanced drugs that are used for conditions such as:

  • deterioration of cognitive functions, memory, attention;

  • loss of performance, endurance, with constant fatigue;

  • sudden mood swings, depressions, phobias.

In childhood, drugs are prescribed for hyperactivity, increased excitability, difficulty in perceiving new information. Also L tyrosine is indicated for age-related disorders of the brain and nervous system. To enhance the effect, phenylalanine is present in addition to tyrosine in supplements.

The method of application for each supplement is indicated in the instructions. In most cases, dietary supplements are drunk in the morning one hour before meals. Wash down with water or juice at room temperature.The average course duration is 30-45 days.

Side effects and contraindications

Dosages and duration of admission are selected by specialists. The drugs did not have any side effects if the selected regimen was followed.

Possible contraindications:

  • Pregnancy and breastfeeding.

  • Hyperthyroidism

  • Hypertension.

  • Taking antidepressants based on monoamine oxidase inhibitors.

  • Allergic reactions to the components of the drug.

  • Schizophrenia.

If you start taking an L tyrosine supplement at the same time as other symptoms, it is recommended that you stop taking it and seek medical advice.

Order L-thyroxine 100mkg 50 pcs tab Ozone (Ozone LLC) in the online pharmacy

City pharmacies:

Domodedovo airport, 2nd floor
Mon-Sun round the clock

In stock, 98 ₽

Vidnoe, Construction st., D.3, pom. 19-25
Mon-Sun 8: 00-20: 00
8 (495) 419-24-84

Domodedovo airport, 1st floor
Mon-Sun round the clock

Golikovo, Uskovsky pr-d, 2
Mon-Sun 9: 00-22: 00
+7 495 419-15-65

Zhukovsky, Club street, 4/8
Mon-Sun 9: 00-21: 00
+7 495 221-53-88

Moscow st.Suschevsky Val, 5, p. 5.
Mon-Fri 08: 00-21: 00, Sat-Sun 09: 00-20: 00
8 (495) 419 29 10

Moscow, Avtozavodskaya st., 13/1
Mon-Fri 8: 00-22: 00, Sat-Sun 9: 00-22: 00
+7 (495) 419-24-50

Moscow, Zhivopisnaya st., 12
Mon-Fri 8: 00-22: 00, Sat 8: 00-21: 00, Sun 9: 00-21: 00
+7 495 419-06-22

Moscow, Nizhnyaya Krasnoselskaya street, 35, from 49
Mon-Fri 9: 00-22: 00, Sat-Sun 10: 00-22: 00
+7 495 419 13 48

Moscow, Zamora Machela st., 2A
Mon-Fri 9: 00-22: 00, Sat-Sun 9: 00-21: 00
+7 495 419-12-51

Moscow, st.Bolshaya Tulskaya, 11
Mon-Fri 08: 00-21: 00, Sat-Sun 09: 00-20: 00
8 (495) 419 30 12

Noginsk, 1st Ilyicha st., Building 6/29
Mon-Sun 9: 00-22: 00
+7 495 221-53-85

Noginsk, Dmitry Mikhailov st., 1
Mon-Sun 9: 00-22: 00
+7 495 419-06-21

Odintsovo urban district, Trekhgorka, st.Trekhgornaya, 4
Mon-Sun 09: 00-21: 00
+7 (495) 419-12-85

Khimki, Leninsky prospect, 1k1
Mon-Sun 8: 00-21: 00
+7 495 419 12 97


1 tablet of 100 mcg contains :

Active ingredient: sodium levothyroxine – 0.1 mg.

Excipients: lactose (milk sugar) – 75.0 mg, povidone (polyvinylpyrrolidone) – 2.4 mg, magnesium stearate – 0.5 mg, pregelatinized starch – 5.0 mg, microcrystalline cellulose – 17.0 mg.

Dosage form



Tablets, white or white with a creamy shade, flat-cylindrical, beveled on both sides and scored on one side.


Synthetic levorotatory isomer of thyroxine.After partial transformation into triiodothyronine (in the liver and kidneys) and transition to the cells of the body, it affects the development and growth of tissues, and metabolism.

In small doses, it has an anabolic effect on protein and fat metabolism.

In medium doses, it stimulates growth and development, increases tissue oxygen demand, stimulates the metabolism of proteins, fats and carbohydrates, increases the functional activity of the cardiovascular system and the central nervous system.

In large doses, inhibits the production of thyrotropin-releasing hormone of the hypothalamus and thyroid-stimulating hormone of the pituitary gland.

The therapeutic effect is observed after 7-12 days, during the same time the effect persists after the drug is discontinued. The clinical effect in hypothyroidism is manifested after 3-5 days. Diffuse goiter decreases or disappears within 3-6 months.


When taken orally, levothyroxine sodium is absorbed almost exclusively in the upper part of the small intestine. Up to 80% of the taken dose of the drug is absorbed. Reception of food reduces the absorption of levothyroxine sodium. The maximum serum concentration is reached approximately 5-6 hours after ingestion.

After absorption, more than 99% of the drug binds to serum proteins (thyroxine-binding globulin, thyroxine-binding prealbumin and albumin). In various tissues, monodeiodination of approximately 80% of sodium levothyroxine occurs with the formation of triiodothyronine (T 3 ) and inactive products.

Thyroid hormones are metabolized mainly in the liver, kidneys, brain and muscles. A small amount of the drug undergoes deamination and decarboxylation, as well as conjugation with sulfuric and glucuronic acids (in the liver).

Metabolites are excreted by the kidneys and through the intestines. The half-life of the drug is 6-7 days. With thyrotoxicosis, the half-life is shortened to 3-4 days, and with hypothyroidism it is extended to 9-10 days.

Indications for use

– Hypothyroidism,

– euthyroid goiter,

– as replacement therapy and to prevent recurrence of goiter after resection of the thyroid gland,

– thyroid cancer (after surgical treatment),

– diffuse toxic goiter: after reaching the euthyroid state with thyreostatics (in the form of combined or monotherapy),

– as a diagnostic tool when performing a thyroid suppression test.


In case of an overdose of the drug, symptoms characteristic of thyrotoxicosis are observed : palpitations, heart rhythm disturbances, heart pain, anxiety, tremors, sleep disturbances, excessive sweating, increased appetite, weight loss, diarrhea. Depending on the severity of symptoms, the doctor may recommend a decrease in the daily dose of the drug, a break in treatment for several days, the appointment of beta-blockers. After the disappearance of side effects, treatment should be started with caution with a lower dose.

Application during pregnancy and breastfeeding

During pregnancy and breastfeeding, therapy with the drug prescribed for hypothyroidism should be continued. During pregnancy, an increase in the dose of the drug is required due to an increase in the level of thyroxin-binding globulin.

The amount of thyroid hormone secreted in breast milk during lactation (even when treated with high doses of the drug) is not enough to cause any disturbance in the child.

The use of the drug in combination with antithyroid drugs during pregnancy is contraindicated, since taking levothyroxine sodium may require an increase in the dose of antithyroid drugs. Since antithyroid drugs, unlike levothyroxine sodium, can cross the placenta, the fetus may develop hypothyroidism.

During breastfeeding, the drug should be taken with caution, strictly in recommended doses under medical supervision.

Side effects

With the correct use of L-thyroxine under the supervision of a physician, side effects are not observed.

In case of hypersensitivity to the drug, allergic reactions may occur.

The development of other side effects is due to an overdose of the drug (see the Overdose section)).


Levothyroxine sodium enhances the effect of indirect anticoagulants, which may require a reduction in their dose.

The use of tricyclic antidepressants with levothyroxine sodium may lead to an increase in the effect of antidepressants.

Thyroid hormones may increase the need for insulin and oral hypoglycemic drugs.More frequent monitoring of blood glucose concentration is recommended during the periods of initiation of treatment with levothyroxine sodium, as well as when changing its dosage regimen.

Levothyroxine sodium reduces the action of cardiac glycosides.

With the simultaneous use of colestyramine, colestipol and aluminum hydroxide, the plasma concentration of sodium levothyroxine is reduced by inhibiting its absorption in the intestine.

With simultaneous use with anabolic steroids, asparaginase, tamoxifen, pharmacokinetic interaction is possible at the level of protein binding.

With simultaneous use with phenytoin, salicylates, clofibrate, furosemide in high doses, the content of sodium levothyroxine and thyroxine, not associated with blood plasma proteins, increases (T 4 ).

Taking estrogen-containing drugs increases the content of thyroxine-binding globulin, which may increase the need for sodium levothyroxine in some patients.

Growth hormone, when used simultaneously with sodium levothyroxine, can accelerate the closure of the epiphyseal growth zones.

Taking phenobarbital, carbamazepine and rifampicin may increase the clearance of sodium levothyroxine and require an increase in the dose.

The distribution and metabolism of the drug is influenced by amiodarone, aminoglutethimide, PASK, ethionamide, antithyroid drugs, beta-blockers, carbamazepine, chloral hydrate, diazepam, levodopa, dopamine, metoclopramide, lovastatin, somatostatin.

When used simultaneously with phenytoin, salicylates, furosemide (in high doses), clofibrate, the concentration of the drug in the blood increases.

Phenytoin reduces the amount of levothyroxine bound to the protein and the concentration of T 4 by 15 and 25%, respectively.

Route of administration and dosage

The daily dose is determined individually depending on the indications.

L-thyroxine in a daily dose is taken orally in the morning on an empty stomach, at least 30 minutes before a meal, with a tablet with a small amount of liquid (half a glass of water) and without chewing.

When carrying out replacement therapy for hypothyroidism in patients younger than 55 years old in the absence of cardiovascular diseases, L-thyroxine is prescribed in a daily dose of 1.6-1.8 μg / kg body weight, in patients over 55 years old or with cardiovascular – vascular diseases – 0.9 μg / kg of body weight.With severe obesity (BMI 30 kg / m 2 ), the calculation should be made for the ideal weight.

Initial stage of replacement therapy for hypothyroidism

Patients without cardiovascular diseases under 55 years old

– Initial dose:

women – 75-100 9000 mcg / day men – 100-150 μg / day

Patients with cardiovascular diseases or older than 55 years

– Initial dose – 25 μg per day

– Increase by 25 μg with an interval of 2 months until the indicator normalizes TSH in the blood

– If symptoms of the cardiovascular system appear or worsen, correct therapy for cardiovascular diseases

10-159 9000

Recommended doses of levothyroxine for the treatment of congenital hypothyroidism 90974


0 Age

Suto high dose of levothyroxine (μg)

Dose of levothyroxine per body weight (μg / kg)

0-6 months


6-12 months



1-5 years



6-12 years old



>, 12 years old


90 2-3

0 thyroid gland cancer



Recommended doses (L-Thyroxine μg / day)

Treatment of euthyroid goiter



Prevention of recurrence after surgical treatment of euthyroid goiter


In complex therapy of thyrotoxicosis


Thyroid suppression test

4 weeks before test

3 weeks before test


One week before the test

L- Thyroxine

75 μg / day

75 μg 90 μg / day



150-200 μg / day

G ore children and children under 3 years old t daily dose of L-thyroxine is given in one dose 30 minutes before the first feeding.The tablet is dissolved in water to a fine suspension, which is prepared immediately before taking the drug.

With hypothyroidism L-thyroxine is taken, as a rule, throughout life.

With thyrotoxicosis L-thyroxine is used in complex therapy with antithyroid drugs after reaching the euthyroid state. In all cases, the duration of drug treatment is determined by the doctor.


In case of an overdose of the drug, symptoms characteristic of thyrotoxicosis are observed: palpitations, heart rhythm disturbances, heart pain, anxiety, tremors, sleep disturbances, excessive sweating, increased appetite, weight loss, diarrhea.Depending on the severity of symptoms, the doctor may recommend a decrease in the daily dose of the drug, a break in treatment for several days, the appointment of beta-blockers. After the disappearance of side effects, treatment should be started with caution with a lower dose.

Special instructions

In hypothyroidism caused by damage to the pituitary gland, it is necessary to find out whether there is simultaneously adrenal insufficiency. In this case, replacement therapy with glucocorticosteroids should be started before starting treatment for hypothyroidism with thyroid hormones in order to avoid the development of acute adrenal insufficiency.

It is recommended to periodically determine the concentration of thyroid-stimulating hormone (TSH) in the blood, an increase in which indicates an insufficient dose.

Influence on the ability to drive vehicles and use mechanisms

The drug has no effect on activities related to driving vehicles and operating mechanisms.

Release form

Tablets 100 mcg.

Terms of dispensing from pharmacies


Storage conditions

Store in a dry, dark place at a temperature not exceeding 25 C.

Keep out of reach of children.

Expiry date

3 years. Do not use after the expiration date.

Manufacturer and organization accepting consumer claims

Ozone LLC

Patient reminder: if you are taking L-thyroxin

Murzaeva Irina Yurievna


You were prescribed either Bagotir-thyroxin or L-thyroxin , or Thyroid, Thyrocomb, Triiodothyronine, Novotiral, or Levothyroxine sodium of other brands).

There are several important rules for taking the drug:
  1. L-thyroxine is always taken before meals for 20-30 minutes, you need to drink with water (not milk, not juice, not tea or coffee, not carbonated water !!!).
  2. If you forget to take the drug before meals, you can take it 3-4 hours after.
  3. In some cases, when a large dose is required, and the drug is not well tolerated, it is allowed to divide the intake into 2-3 times a day, that is, 3-4 hours after a meal and 30 minutes before the next meal.
  4. Some schemes allow you to skip taking L-thyroxine 1 day a week or 2 days a week, but not in a row. The doctor usually talks about such a scheme at the reception. This applies to patients with a history of coronary artery disease, arrhythmias, elderly patients (over 75 years old), etc.
  5. Do not try to change the dose yourself! If you feel discomfort while taking the drug, you need to take a blood test for hormones (at least TSH, free T4, free T3) and come to the doctor’s office.This is especially important for women during pregnancy, when the dose of the drug is fundamental !!!
  6. With a selected dose, hormones are monitored, usually 2 times a year. When choosing a dose – once every 2 months.
  7. There are schemes in which the dose is changed seasonally (in autumn and winter – the dose is higher, in spring and summer – lower), the scheme is prescribed only by a doctor, and not independently.
  8. The most common side effects: palpitations, sweating, irritability, if they persist within 10 days, it is worth discussing with your doctor changing the dose or changing the regimen of the drug.
  9. L-thyroxine is not combined when taken simultaneously with drugs: iron, calcium, antacids (Maalox, Almagel, etc.), the difference between taking these drugs should be 4 hours. It is advisable not to mix with other preparations either (minimum interval 15 minutes).
  10. During pregnancy, the entire dose of the drug is prescribed immediately, in other conditions it is selected gradually under the control of hormones! (this is called “dose titration”, the dose is changed once every 1-5 weeks, it is decided by the doctor).
  11. When the drug is discontinued, the entire dose is canceled at once, without a gradual decrease.
  12. Due to surgery or other circumstances, L-thyroxine may not be taken for a maximum of 1 week!
  13. It is quite rare that patients have a very high sensitivity to the drug and the dose taken is only 12.5 mcg, 25 mcg or 37.5 mcg, higher doses cause an overdose sensation.
  14. It is advisable not to “grind” the drug, but to buy the full dose required for taking, for example, Eutirox is produced in doses – 25, 50, 75, 88, 100, 125, 112, 125, 137, 150 mcg! From Germany, you can bring Eutirox at a dose of 200 mcg, 300 mcg.
  15. When taking L-thyroxine in menopause, it is necessary to combine it with taking calcium supplements in a course mode, under the control of bone density (densitometry) once every 3-5 years, and with already diagnosed osteoporosis and its treatment – once a year …
  16. L-thyroxine is officially approved during pregnancy and lactation.
  17. The need for L-thyroxine is greater in children than in adults, due to the increased rate of metabolic processes, this is associated with growth processes.
  18. Taking L-thyroxine and other drugs at the same time (such as anticoagulants, COCs, glucocorticoids, prednisolone, etc.)) can change the indicators of TSH, T4 free, T3 free blood, changes in which can only be assessed by a doctor !!!
  19. L-thyroxine changes the metabolism in the body (its metabolism changes in relation to the drugs taken) – antidepressants, cardiac glycosides, anticoagulants, some hypoglycemic drugs, anabolic drugs, tamoxifen, furosemide, phenobarbital, carbamazepine, salicylates, amiodarone, some others check with the doctor the effects and dose of the drug in your case.Do not forget to provide your doctor with a complete list of medications you are taking!
  20. L-thyroxine is used not only for the treatment of hypothyroidism, but also for the treatment of nodular goiter, diffuse enlargement of the thyroid gland, in some cases of treatment of thyroid disease, after surgery on the thyroid gland.