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Levothyroxine water retention: Does levothyroxine cause weight gain or loss?

Does levothyroxine cause weight gain or loss?

Medically reviewed by Sally Chao, MD. Last updated on Sep 3, 2021.

In most cases, levothyroxine causes some weight loss. According to the American Thyroid Association, when this medication is started, you may lose up to 10% of your weight. This weight is mainly water weight, since being hypothyroid makes you retain water.

Levothyroxine is a medication to treat hypothyroidism. Since weight gain is one of the symptoms of hypothyroidism, taking thyroid replacement with levothyroxine may reverse that weight gain. You may return to the normal body weight you would have been without the fluid retention caused by hypothyroidism.

Once your thyroid levels are normal again, this medication should have no effect on your weight.

Levothyroxine should not be used to treat obesity or for weight loss. This can cause dangerous side effects, especially if you combine levothyroxine with another drug that causes weight loss, such as dextroamphetamine or methamphetamine.

Side effects of levothyroxine to watch for and contact your doctor about include:

  • Nausea
  • Vomiting
  • Headache
  • Diarrhea
  • Joint pain or muscle cramps
  • Fever
  • Increased heat sensitivity
  • Appetite changes
  • Menstrual cycle changes in women.

Taking too much levothyroxine can cause overdose symptoms that include:

  • A racing heart
  • Chest pain
  • Shortness of breath
  • Anxiety
  • Irritability
  • Tremors
  • Insomnia
  • Sweating.

Levothyroxine is an oral medication that comes in a capsule or tablet. You take it once each day on an empty stomach, usually before breakfast. It may take several weeks for your thyroid levels to return to normal.

Symptoms of hypothyroidism that may be reversed with levothyroxine include:

  • Lack of energy
  • Constipation
  • Skin that’s thick and dry
  • Fatigue
  • Increased cold sensitivity
  • Hair loss
  • Pain in your joints and muscles
  • Irregular menstrual periods in women
  • Depression.

You should not stop taking levothyroxine on your own, even if you feel better. This can result in a return of hypothyroidism.


  1. American Thyroid Association (ATA). Thyroid and Weight. Available at: https://www.thyroid.org/thyroid-and-weight/. [Accessed August 9, 2021].
  2. U.S. National Library of Medicine MedlinePlus. Levothyroxine. July 2021. Available at: https://medlineplus.gov/druginfo/meds/a682461.html. [Accessed August 9, 2021].

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Medical Disclaimer

Levothyroxine and Weight Gain: How to Manage Weight

Hormones produced by the thyroid gland help regulate metabolism, so if you have an underactive thyroid—a condition called hypothyroidism—you may gain excess weight and struggle to lose it.

The thyroid also affects energy levels, which can make physical activity a challenge if you feel fatigued. This can further contribute to difficulty losing or maintaining weight.

However, there are many other factors that can contribute to weight gain, and getting your thyroid hormones in balance is only one aspect of weight management. It’s important to note that the majority of the time, weight changes are due to causes other than hypothyroidism.

How Your Thyroid and Weight Are Related

The relationship between thyroid hormones and weight regulation is complex. The American Thyroid Association notes that weight gain develops over a long time and may have many causes other than the underactive thyroid. Generally, about 5 to 10 pounds of excess weight can likely be attributed to the lack of thyroid hormones that occurs in people diagnosed with hypothyroidism. The weight is mostly water retention, rather than fat.

Once hormone levels are regulated through medication, people typically experience a modest amount of weight loss, if any—usually less than 10% of body weight, the ATA says.

One study of 101 people with hypothyroidism found that 52% lost weight after starting treatment with thyroid hormone replacement, with an average loss of 8.4 pounds. Researchers concluded that “contrary to popular belief,” starting medication results in “no significant weight change.” (On the other hand, losing even a little bit of weight is better than losing none in terms of benefitting your overall health.)

What Is Levothyroxine and Why Did Your Doctor Prescribe It?

Levothyroxine is a synthetic form of the hormone thyroxine, or T4, and the most commonly used medication for underactive thyroid. It is also prescribed to people who had thyroid cancer and underwent surgery or radiation, since these treatments result in a reduction or total loss of the thyroid gland and the hormones it produces.

Levothyroxine starts working right away but it may take several weeks to notice a change in symptoms. Doses may need to be periodically adjusted (every two to three months at the beginning).

Does Levothyroxine Cause Weight


Both weight gain and weight loss are possible side effects. Many people do not take the right dosage of levothyroxine, and both undertreatment and overtreatment can have an effect on weight.

Levothyroxine weight gain may be tied to undertreatment, according to the ATA. To avoid this, people with a higher body weight should be prescribed a higher starting dose; doses should then be adjusted whenever there is a significant change in body weight. Blood testing will be used to monitor your hormone levels for medication adjustments.

While undertreatment with levothyroxine can lead to weight gain, overtreatment can result in weight loss as well as adverse effects including bone and muscle loss and heart problems, especially arrhythmias. Once the excess hormone is stopped (that is, the dose is adjusted downward), the weight is typically regained. The U.S. Food and Drug Administration (FDA) warns that thyroid hormones should not be used for weight loss or for treating obesity.

Hyperthyroidism and Weight Gain

Some people with a history of hyperthyroidism, or overactive thyroid, end up taking levothyroxine because their treatment induces hypothyroidism. For instance, radioactive iodine or thyroid surgery (thyroidectomy) can lower thyroid production too much, prompting the need for levothyroxine.

The largest weight changes associated with thyroid conditions actually occur in people being treated for hyperthyroidism, not hypothyroidism. People with overactive thyroid may go from losing weight without trying to gaining potentially too much.

One possible explanation is that people maintain the same eating habits they had when their metabolisms were abnormally high. In one study of 1,373 patients treated for an overactive thyroid, men gained nearly 18 pounds and women gained 12 pounds. Additionally, they were more likely to become obese than a control group.

Tips for Managing Weight When You’re Taking Levothyroxine

Once your underactive thyroid is successfully treated with levothyroxine, you should have the same ability to gain or lose weight as those with normal thyroid function, according to the ATA. If all the other symptoms you were experiencing resolve with medication, minus the weight gain, it’s unlikely the excess weight was solely due to your thyroid.

Sustainable weight loss, which is losing 1 or 2 pounds a week, calls for a combination of exercise and healthy eating for optimal thyroid function.

The Centers for Disease Control and Prevention (CDC) recommends aiming for 150 minutes of moderate-intensity physical activity weekly. Start with activities you enjoy and look for ways to reduce sitting.

Aerobic activity has been shown to increase T4 concentrations in the blood. Workouts that get your heart pumping include swimming, cycling, brisk walking, or using an elliptical machine.

If fatigue is an issue, plan physical activity for times in the day or week when you feel most energetic. As you develop an exercise routine, you’ll likely see improvements in energy, mood, and confidence.

You can also build physical activity into your workday by walking during your lunch break and taking the stairs when possible.

If you’ve recently lost weight, you’ll have a better chance of maintaining it by monitoring activity and diet. You may need to do more than 150 minutes of exercise per week. People who maintain their weight loss typically exercise for 60 to 90 minutes most days of the week, according the CDC.

Notes: This article was originally published August 30, 2022 and most recently updated September 15, 2022.

Weight and hypothyroidism: American Thyroid Association. (No date). Thyroid and Weight. Accessed August 30, 2022.

Side effects of levothyroxine: NIH National Library of Medicine, MedlinePlus. Levothyroxine. Last revised 2/15/19. Accessed August 30, 2022.

Improper dosing, use of body weight for levothyroxine dosage: American Thyroid Association, Clinical Thyroidology for the Public. June 2018 issue. Hypothyroidism.

Levothyroxine metabolism: Younis IR, Ahmed MA, Burman KD, Soldin OP, Jonklaas J. Stable Isotope Pharmacokinetic Studies Provide Insight into Effects of Age, Sex, and Weight on Levothyroxine Metabolism. Thyroid. 2018 Jan;28(1):41-49. doi: 10.1089/thy.2017.0380. Epub 2018 Jan 2.

Thyroid medication and weight studies: Lee SY, Braverman LE, Pearce EN. Changes in body weight after treatment of primary hypothyroidism with levothyroxine. Endocr Pract. 2014 Nov;20(11):1122-8. doi: 10.4158/EP14072.

Alidrisi HA, Odhaib SA, Altemimi MT, Mansour AA. Patterns of Bodyweight Changes in Patients With Hypothyroidism, a Retrospective Study From Basrah, Southern Iraq. Cureus. 2021 Jun 2;13(6):e15408. doi: 10.7759/cureus.15408.

Boelaert K, Torlinska B, Nichols L. et al. Patients treated for hyperthyroidism are at increased risk of becoming obese: findings from a large prospective secondary care cohort. Thyroid. 2019;29(10):1380-1389.

Diet and exercise advice: Ventura M, Melo M, Carrilho F. Selenium and Thyroid Disease: From Pathophysiology to Treatment. Int J Endocrinol. 2017;2017:1297658. doi: 10.1155/2017/1297658. Epub 2017 Jan 31.

Maxwell C, Volpe SL. Effect of zinc supplementation on thyroid hormone function. A case study of two college females. Ann Nutr Metab. 2007;51(2):188-94. doi: 10.1159/000103324. Epub 2007 May 30.

Centers for Disease Control and Prevention. Getting Started with Physical Activity. Page last reviewed 6/16/22. Accessed August 30, 2022.

Ciloglu F, Peker I, Pehlivan A, Karacabey K, Ilhan N, Saygin O, Ozmerdivenli R. Exercise intensity and its effects on thyroid hormones. Neuro Endocrinol Lett. 2005 Dec;26(6):830-4. Erratum in: Neuro Endocrinol Lett. 2006 Jun;27(3):292.

Our Review Process

causes, pathogenesis, symptoms, treatment of edema

Article content:

  • What is hypothyroidism
  • Edema as a symptom of disease
  • Causes of edema
  • Characterization of edema
  • Methods of treatment
  • Prognosis and prevention

What is hypothyroidism

Hypothyroidism is a disease in which the hormonal function of the thyroid gland is impaired. It produces thyroxine and triiodothyronine, which control cellular metabolism. Suppression of the hormone-producing function of the organ leads to a decrease in the content of T3 and T4 in the blood, deterioration of metabolism, disruption of the internal organs.

Causes of hypothyroidism:

  • iodine deficiency in drinking water and food;
  • inflammation of thyroid tissue;
  • removal of part or all of an organ;
  • dysfunction of the pituitary gland, which regulates the functioning of the thyroid gland.

At the initial stage, hypothyroidism is asymptomatic, since the work of the gland is supported by compensatory mechanisms. After their depletion, a clinically pronounced phase of the disease begins.

Edema as a symptom of the disease

Edema is one of the most persistent symptoms of hypothyroidism. Edema is watery and mucous, formed on the arms and legs, face and trunk Source:
Hypothyroidism in the practice of a general practitioner. Timofeeva N.Yu., Stomenskaya I.S., Kostrova O.Yu. Acta Medica Eurasica. 2022. №1. pp.39-43. Widespread edema that affects the entire body is called myxedema. Its formation indicates an extremely severe course of the disease. Myxedema affects not only subcutaneous fat, but also internal organs.

Causes of edema

Deceleration of metabolism in cells leads to fluid retention in tissues. At first, the accumulation of water is imperceptible externally, the patient may notice only a small increase in body weight. Then the fluid in the tissues becomes more and more, first pastosity appears, then swelling.

Prolonged hormone deficiency without treatment or with incorrect therapy leads to accelerated breakdown of proteins in tissues. Protein degradation products are able to attract and accumulate water, resulting in the formation of a mucus-like substance – mucin. The accumulation of mucus in the intercellular spaces leads to the formation of mucinous edema. Source:
Edema syndrome in patients with hypothyroidism. Features of diagnosis and treatment. Kryuchkova O.N., Turna E.Yu. Crimean therapeutic journal. 2010. №1. pp.4-7. They are denser than water, do not disappear after taking diuretics.

Characteristics of edema

Edema in hypothyroidism does not have a specific localization. They occur in different parts of the body, and in the severe course of the disease, myxedema develops, capturing the entire body. Water edema is soft and mobile; when pressed, it leaves a deep hole, which quickly disappears. They usually appear under the eyes, on the forearms and shins.

Mucous edemas are dense and immobile, when pressed on them, a small depression remains, which persists for a long time. Myxedema is also referred to as mucous edema. Such puffiness is most noticeable in places with well-developed subcutaneous fat – on the face, neck, abdominal wall, back.

Myxedematous face – a characteristic sign of hypothyroidism:

  • puffy, mask-like face;
  • coarse facial features, enlarged chin;
  • bags, dark circles under the eyes;
  • mouth ajar;
  • the skin is dry, flaky.

Mucosal edema in hypothyroidism leads to difficulty in nasal breathing, constant coughing. The voice becomes hoarse, rough. Mucin can also accumulate in body cavities – abdominal, thoracic, cardiac. The effusion compresses the organs located in these cavities, and causes a violation of their work.

Of the internal organs, the heart is the first to suffer. To describe the clinic of hypothyroidism, a term such as myxedematous heart is used. Mucinous effusion accumulates in the atria and ventricles, the heart sac Source:
Edema syndrome. Chukaeva I.I., Orlova N.V. Medical business. 2007. No. 2. pp.72-80. This leads to a violation of the contractility of the heart, causes stagnation of blood in the cavities, their irreversible expansion. The manifestations of myxedematous heart are arrhythmia, fluctuations in blood pressure, shortness of breath.

Diagnosis of external edema does not require a special examination, they are noticeable during examination and palpation. Ultrasound helps to detect effusion in body cavities.

Methods of treatment

Water edema in hypothyroidism is easier to remove than mucous membranes. With severe swelling, drugs with a diuretic effect are used, potassium and magnesium are additionally prescribed to prevent seizures. Source:
Hypothyroidism: the current state of the problem. Biryukova E.V., Kileinikov D.V., Solovieva I.V. MS. 2020. No. 7. pp.96-107.

Therapeutic diet helps to manage swelling and prevent its recurrence. From the diet it is recommended to exclude foods that contribute to water retention in tissues:

  • baked goods;
  • confectionery, sweets, chocolate;
  • salted fish, preserves, marinades;
  • carbonated soft drinks, alcohol.

The following products improve metabolism and digestion, prevent the formation of puffiness:

  • fresh vegetables and fruits;
  • seafood;
  • buckwheat and oatmeal;
  • fermented milk products.

Some plants have a diuretic effect – bearberry, lingonberry leaf. It is recommended to make tea from them, and take it as a decongestant. With mucinous edema, myxedema, diuretics are ineffective. It is necessary to influence the mechanism of mucin formation itself. For this, hormone replacement therapy with levothyroxine is used. After the normalization of the hormonal profile, the metabolism is restored, the mucin breaks down and the edema disappears.

Prognosis and prevention

Water edema does not pose a threat to health and life. Myxedema is more dangerous because it compresses tissues and causes irreversible changes. Mucinous effusion in the pleural cavity or pericardium leads to respiratory and heart failure. But myxedema progresses slowly, so the prognosis for most patients is favorable, provided that they start treatment with an endocrinologist in a timely manner. Source:
Endocrinology. National leadership. Dedov I.I., Melnichenko G.A. Moscow: GEOTAR-Media. 2013. pp. 338-345.

Prevention of myxedema consists in following a healthy lifestyle, the principles of therapeutic nutrition, and timely prescribing hormone therapy.

  • Hypothyroidism in the practice of a general practitioner. Timofeeva N.Yu., Stomenskaya I.S., Kostrova O.Yu. Acta Medica Eurasica. 2022. №1. p.39-43
  • Edema syndrome in patients with hypothyroidism. Features of diagnosis and treatment. Kryuchkova O.N., Turna E.Yu. Crimean therapeutic journal. 2010. №1. p.4-7
  • Edema syndrome. Chukaeva I.I., Orlova N.V. Medical business. 2007. No. 2. p.72-80
  • Hypothyroidism: current state of the problem. Biryukova E.V., Kileinikov D.V., Solovieva I.V. MS. 2020. No. 7. p.96-107
  • Endocrinology. National leadership. Dedov I.I., Melnichenko G.A. Moscow: GEOTAR-Media. 2013. p.338-345

Article published on : 03/02/2023
Last updated : 03/02/2023

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