Symptoms and what to do

Taking too much antihistamine can lead to adverse side effects and a potential antihistamine overdose.

Antihistamines are a class of medication that treat allergy symptoms, such as sneezing, runny nose, and itching. As with any medication, taking too much can be harmful. Some antihistamines also work as sleep aids, cold and flu medicine, and motion sickness treatment.

People should follow the dosage guidelines on the packaging or their doctor’s advice to avoid an overdose. They should also keep antihistamines, and all medications, out of reach of children.

Always call a doctor or a poison control center if an antihistamine overdose occurs.

Share on PinterestA person who overdoses on antihistamines may experience fever, dilated pupils, and a fast heart rate.

People can overdose on any type of antihistamine. Antihistamines are a drug, and there is a safe limit to how much a person can take at one time.

This limit depends on several factors, including:

• the age and size of the person
• the type of antihistamine they took and how much
• any health conditions they have
• other medication the person takes

If a healthy adult takes only a slightly higher dose of antihistamine, such as accidentally taking two pills instead of one, their symptoms may not be serious, or they may not have any symptoms.

However, a larger overdose, especially in children or older adults, may cause serious symptoms. Toxic doses of antihistamines may happen when a person takes 3 to 5 times the normal amount.

No matter how much a person overdoses, they should seek medical help or call a poison control center.

A position statement from the Canadian Society of Allergy and Clinical Immunology (CSACI) states that first generation antihistamines can have “intolerable and potentially life threatening adverse effects.”

Research shows that first generation antihistamines can have effects on the central nervous system in large doses.

Examples of first generation antihistamines include:

• diphenhydramine (Benadryl)
• chlorpheniramine
• brompheniramine

These antihistamines may cause jitteriness or drowsiness.

Second generation antihistamines do not usually have these effects. Second-generation antihistamines are commonly used medications, including:

• loratadine (Claritin)
• cetirizine (Zyrtec),
• fexofenadine (Allegra)

Signs and symptoms of antihistamine overdose in children may include:

• being very excited or jittery
• a fast heart rate
• irritability
• hallucinations
• seizures

After these symptoms appear, a child may experience:

• drowsiness
• slowed breathing
• coma

Symptoms of antihistamine overdose in adults may include:

• fever
• flushing
• dilated pupils
• fast heart rate (tachycardia)
• low blood pressure (hypotension)
• coma
• an inability to empty the bladder completely (urinary retention)

Second generation antihistamines tend to be less serious with an overdose. However, any overdose can be dangerous, and people should seek help from a medical professional or poison control immediately.

If a person suspects an antihistamine overdose, they should call the American Association of Poison Control Centers (AAPCC) at 1-800-222-1222. The AAPCC helpline is open 24 hours and is toll-free.

If a person has severe symptoms, such as trouble breathing, fast or slow heart rate, seizures, or loss of consciousness, call 911 or go to the nearest emergency room.

Some antihistamines are safe for children to take. However, the Food and Drug Administration (FDA) caution that just because a product says it is for children does not mean a child of any age can take it.

Research on antihistamines says that children and older adults are more at risk of an antihistamine overdose than adults.

One study found that children have experienced heart problems, seizures, and even death from an antihistamine overdose. The most common reactions are mild, however, and include:

• rashes
• sleepiness
• headache

Second generation antihistamines are less likely to cause toxicity in children than first generation ones, according to a study of more than 9,000 children.

However, another study foundthat second generation antihistamines can cause dangerous symptoms when children overdose on them.

Diagnosing an antihistamine overdose usually starts with a discussion about all medications the person is taking and not just the antihistamines. This is because some other medications, such as cold, flu, and sleep medications, contain antihistamines.

If a person takes one of these other medications and also takes an allergy medication, they may accidentally overdose.

Other medications, such as certain antidepressants and motion sickness drugs, can also cause an overdose if a person mixes them with antihistamines.

If someone is not sure about the amount of antihistamine they took, a doctor may need to conduct a physical exam. They may look for signs such as drowsiness, irritability, blurred vision, or seizures. They may also check the heart rate, breathing rate, and blood pressure.

In some cases, a person may need blood tests or further observation in a hospital.

In mild cases, an individual may be able to use self-care at home. However, they should always call the AAPCC or a doctor to be sure this is safe.

If the person is experiencing serious symptoms, they may need hospitalization, including heart monitoring, intravenous (IV) fluids, and medication.

In some cases, doctors may give a person activated charcoal, which helps prevent the absorption of some medications and chemicals in the gut. They may also use ipecac syrup, which causes the person to vomit. This can cause any excess medication to leave the body in the vomitus.

Antihistamines may be first generation (sedating) or second generation (nonsedating). These two types may lead to different reactions if a person takes too much.

First generation antihistamines are more likely to cross the blood-brain barrier. This means they can make people dizzy or drowsy, even in normal doses.

Second generation antihistamines are newer drugs and are less likely to have these effects. Nonetheless, people can overdose on both types.

First generation antihistamines available over-the-counter include:

• diphenhydramine (Benadryl)
• chlorpheniramine (Chlor-Trimeton)
• brompheniramine (Dimetapp)
• clemastine (Tavist)
• doxylamine (Unisom)
• hydroxyzine (Vistaril)
• promethazine (Promethegan)
• triprolidine (Actidil)

These medications can act as sedatives, so they can make a person feel tired or dizzy.

Some experts say first generation antihistamines are more likely to result in death from accidents or overdoses than their second generation counterparts.

Second and third generation antihistamines available over the counter include:

• cetirizine (Zyrtec)
• fexofenadine (Allegra)
• loratadine (Claritin)

These newer antihistamines are less likely to cause drowsiness and dizziness. Research has found them less likely to cause dangerous effects if a person takes too much.

Antihistamines are typically safe when a person takes the correct amount. However, as with any medication, they can cause serious adverse effects if someone takes too much.

People must keep antihistamines and all medications out of reach of children. Some antihistamines are safe for children to take, but it is important to ask a doctor or pharmacist about the right dose.

Different antihistamines have different dosages. It is vital to read labels carefully to be sure a person is not taking too much.

If an overdose happens, seek immediate medical attention or call the AAPCC at 800-222-1222.

Symptoms and what to do

Taking too much antihistamine can lead to adverse side effects and a potential antihistamine overdose.

Antihistamines are a class of medication that treat allergy symptoms, such as sneezing, runny nose, and itching. As with any medication, taking too much can be harmful. Some antihistamines also work as sleep aids, cold and flu medicine, and motion sickness treatment.

People should follow the dosage guidelines on the packaging or their doctor’s advice to avoid an overdose. They should also keep antihistamines, and all medications, out of reach of children.

Always call a doctor or a poison control center if an antihistamine overdose occurs.

Share on PinterestA person who overdoses on antihistamines may experience fever, dilated pupils, and a fast heart rate.

People can overdose on any type of antihistamine. Antihistamines are a drug, and there is a safe limit to how much a person can take at one time.

This limit depends on several factors, including:

• the age and size of the person
• the type of antihistamine they took and how much
• any health conditions they have
• other medication the person takes

If a healthy adult takes only a slightly higher dose of antihistamine, such as accidentally taking two pills instead of one, their symptoms may not be serious, or they may not have any symptoms.

However, a larger overdose, especially in children or older adults, may cause serious symptoms. Toxic doses of antihistamines may happen when a person takes 3 to 5 times the normal amount.

No matter how much a person overdoses, they should seek medical help or call a poison control center.

A position statement from the Canadian Society of Allergy and Clinical Immunology (CSACI) states that first generation antihistamines can have “intolerable and potentially life threatening adverse effects.”

Research shows that first generation antihistamines can have effects on the central nervous system in large doses.

Examples of first generation antihistamines include:

• diphenhydramine (Benadryl)
• chlorpheniramine
• brompheniramine

These antihistamines may cause jitteriness or drowsiness.

Second generation antihistamines do not usually have these effects. Second-generation antihistamines are commonly used medications, including:

• loratadine (Claritin)
• cetirizine (Zyrtec),
• fexofenadine (Allegra)

Signs and symptoms of antihistamine overdose in children may include:

• being very excited or jittery
• a fast heart rate
• irritability
• hallucinations
• seizures

After these symptoms appear, a child may experience:

• drowsiness
• slowed breathing
• coma

Symptoms of antihistamine overdose in adults may include:

• fever
• flushing
• dilated pupils
• fast heart rate (tachycardia)
• low blood pressure (hypotension)
• coma
• an inability to empty the bladder completely (urinary retention)

Second generation antihistamines tend to be less serious with an overdose. However, any overdose can be dangerous, and people should seek help from a medical professional or poison control immediately.

If a person suspects an antihistamine overdose, they should call the American Association of Poison Control Centers (AAPCC) at 1-800-222-1222. The AAPCC helpline is open 24 hours and is toll-free.

If a person has severe symptoms, such as trouble breathing, fast or slow heart rate, seizures, or loss of consciousness, call 911 or go to the nearest emergency room.

Some antihistamines are safe for children to take. However, the Food and Drug Administration (FDA) caution that just because a product says it is for children does not mean a child of any age can take it.

Research on antihistamines says that children and older adults are more at risk of an antihistamine overdose than adults.

One study found that children have experienced heart problems, seizures, and even death from an antihistamine overdose. The most common reactions are mild, however, and include:

• rashes
• sleepiness
• headache

Second generation antihistamines are less likely to cause toxicity in children than first generation ones, according to a study of more than 9,000 children.

However, another study foundthat second generation antihistamines can cause dangerous symptoms when children overdose on them.

Diagnosing an antihistamine overdose usually starts with a discussion about all medications the person is taking and not just the antihistamines. This is because some other medications, such as cold, flu, and sleep medications, contain antihistamines.

If a person takes one of these other medications and also takes an allergy medication, they may accidentally overdose.

Other medications, such as certain antidepressants and motion sickness drugs, can also cause an overdose if a person mixes them with antihistamines.

If someone is not sure about the amount of antihistamine they took, a doctor may need to conduct a physical exam. They may look for signs such as drowsiness, irritability, blurred vision, or seizures. They may also check the heart rate, breathing rate, and blood pressure.

In some cases, a person may need blood tests or further observation in a hospital.

In mild cases, an individual may be able to use self-care at home. However, they should always call the AAPCC or a doctor to be sure this is safe.

If the person is experiencing serious symptoms, they may need hospitalization, including heart monitoring, intravenous (IV) fluids, and medication.

In some cases, doctors may give a person activated charcoal, which helps prevent the absorption of some medications and chemicals in the gut. They may also use ipecac syrup, which causes the person to vomit. This can cause any excess medication to leave the body in the vomitus.

Antihistamines may be first generation (sedating) or second generation (nonsedating). These two types may lead to different reactions if a person takes too much.

First generation antihistamines are more likely to cross the blood-brain barrier. This means they can make people dizzy or drowsy, even in normal doses.

Second generation antihistamines are newer drugs and are less likely to have these effects. Nonetheless, people can overdose on both types.

First generation antihistamines available over-the-counter include:

• diphenhydramine (Benadryl)
• chlorpheniramine (Chlor-Trimeton)
• brompheniramine (Dimetapp)
• clemastine (Tavist)
• doxylamine (Unisom)
• hydroxyzine (Vistaril)
• promethazine (Promethegan)
• triprolidine (Actidil)

These medications can act as sedatives, so they can make a person feel tired or dizzy.

Some experts say first generation antihistamines are more likely to result in death from accidents or overdoses than their second generation counterparts.

Second and third generation antihistamines available over the counter include:

• cetirizine (Zyrtec)
• fexofenadine (Allegra)
• loratadine (Claritin)

These newer antihistamines are less likely to cause drowsiness and dizziness. Research has found them less likely to cause dangerous effects if a person takes too much.

Antihistamines are typically safe when a person takes the correct amount. However, as with any medication, they can cause serious adverse effects if someone takes too much.

People must keep antihistamines and all medications out of reach of children. Some antihistamines are safe for children to take, but it is important to ask a doctor or pharmacist about the right dose.

Different antihistamines have different dosages. It is vital to read labels carefully to be sure a person is not taking too much.

If an overdose happens, seek immediate medical attention or call the AAPCC at 800-222-1222.

what you need to know – Drink-Drink

Overdose warning

It is not safe to take more than the recommended dose of Benadryl, despite social media issues that encourage it. Taking more than recommended can lead to overdose and serious side effects. These include abnormal heart rhythms, seizures, and hallucinations (seeing or hearing something that isn’t really there). In rare cases, it can even lead to death.

If you may have taken too much Benadryl and are experiencing severe symptoms, call 911 or go to the nearest emergency room right away.

Introduction

If you have allergies, a cold, or an allergic rash, your doctor may suggest Benadryl (diphenhydramine) as a treatment option. Along with other questions about the drug, you may be interested in its side effects.

Benadryl is available both by prescription and over the counter (OTC). It helps reduce the symptoms of hay fever (nasal allergy), other allergies, and the common cold. Examples include a runny nose and sneezing.

This drug is also used to treat certain allergic reactions such as swelling and hives. For these purposes, the over-the-counter version of Benadryl can be used by adults and children aged 6 years and older.

Benadryl is available in many different forms. Some of these you take by mouth, such as tablets or liquid solutions. Others that you apply to your skin, such as creams or gels.

You will usually take Benadryl as a short-term treatment for your symptoms. Once your symptoms subside, your doctor will likely recommend that you stop taking Benadryl.

For more information on Benadryl, see this detailed article.

Like all medicines, Benadryl can cause mild or serious side effects. Keep reading to find out more.

What are the most common side effects of Benadryl?

Some people may experience mild or severe side effects while taking Benadryl. Examples of some of the more commonly reported side effects of Benadryl include:

• drowsiness
• dizziness*
• Headache
• blurred vision*
• low blood pressure

What are the mild side effects of Benadryl?

Examples of mild side effects reported with Benadryl include:

• drowsiness
• dizziness*
• Headache
• low blood pressure
• constipation
• dry mouth or nose
• blurred vision*

In most cases, these side effects should be temporary. And some are easy to deal with. But if you have any symptoms that continue or bother you, talk to your doctor or pharmacist. And don’t stop using Benadryl unless your doctor recommends it.

Benadryl may cause mild side effects other than those listed above. For more information, talk to your doctor or pharmacist.

The Food and Drug Administration (FDA) monitors drug side effects. If you would like to notify the FDA of a side effect you had with Benadryl, visit MedWatch.

What are the serious side effects of Benadryl?

Serious side effects that have been reported with Benadryl include:

• changes in blood cell levels, such as a decrease in red blood cells
• heart rhythm problems, including a condition called long QT syndrome
• seizures
• hallucinations (seeing or hearing something that is not really there)
• memory loss or dementia*
• feeling uneasy
• allergic reaction*†
• rapid heartbeat* 90 034

If you develop serious side effects when taking Benadryl, contact your doctor immediately. If the side effects seem life-threatening or if you think you need emergency medical attention, call 9 right away11 or your local emergency number.

Side effects in children

The side effects of Benadryl in children are generally similar to those in adults. But this medicine can also cause hyperactivity and excitability in children.

Benadryl should not generally be used in children under 6 years of age because they may have more serious side effects from the drug. This includes seizures and fast heartbeats.

OTC forms of Benadryl are only approved for use in children 6 years of age and older and adults. If your child is under 6, talk to your doctor about whether Benadryl is safe for them.

Benadryl Side Effects Frequently Asked Questions

Get answers to some frequently asked questions about Benadryl side effects.

Are there any long term side effects of Benadryl?

Yes, it is. Some long-term side effects that Benadryl can cause include:

• dementia
• memory problems
• anxiety
• addiction or withdrawal symptoms such as psychosis when you stop taking Benadryl

Benadryl is only recommended as a short-term treatment for people with symptoms of allergies or other conditions that the drug treats. If you take Benadryl for a long time, you may develop long-term side effects of the medication.

The side effects you experience will determine how long they last. For example, if you feel drowsy, this side effect may last for several hours or until the medication is no longer available to you. But other side effects may be longer lasting.

Talk to your doctor about using Benadryl and what other medicines may be best for your condition.

Do older people have a higher risk of side effects from Benadryl?

Yes, older people (age 65 and over) are likely to have a higher risk of side effects from Benadryl than younger people. This is due to the fact that their body can get rid of the drug more slowly.

Elderly people may have more side effects from Benadryl, including drowsiness, dizziness, or heart problems. Drowsiness and dizziness can increase the risk of falling, which can be very serious.

If you are an older person interested in taking Benadryl, talk to your doctor. They may recommend that you take a lower dose of Benadryl to reduce the risk of side effects. Or they may suggest that you take another medicine to treat allergies or cold symptoms.

Can Benadryl be used in infants or toddlers? If yes, what are the possible side effects?

OTC forms of Benadryl should not be used in infants or young children. This is because children younger than 6 years of age have an increased risk of side effects from Benadryl.

Children may experience the same side effects of Benadryl as adults, such as dizziness or drowsiness. But Benadryl can also cause more serious side effects in children, such as heart palpitations or seizures. The drug can also cause children to become more excitable or hyperactive.

You should never use Benadryl to help your child fall asleep. This can be very dangerous.

Because of these risks, you should not give Benadryl to your child or toddler unless directed by a doctor. If your child has allergy or cold symptoms, talk to your doctor about the best way to treat these symptoms.

Does my risk of side effects from Benadryl vary with dose (eg 25 mg or 50 mg)?

Yes, your risk of side effects may vary depending on the dose of Benadryl you take.

A higher dose of Benadryl may increase the risk of side effects. Thus, you are more at risk of side effects with 50 milligrams (mg) of Benadryl than with 25 mg.

If you have concerns about side effects from a dose of Benadryl, talk to your doctor.

Does Benadryl cause diarrhea?

No, you should not get diarrhea from taking Benadryl. In fact, Benadryl can cause constipation.

Some other medicines used to treat allergy symptoms, such as Allegra Allergy (fexofenadine), can cause diarrhea.

If you have diarrhea while taking Benadryl, talk to your doctor about what might be causing it.

Side effects explained

Find out more about some of the side effects that Benadryl can cause.

Rapid heartbeat

Rapid heartbeat is a common side effect of Benadryl. In rare cases, it can become serious.

Symptoms of a fast heartbeat may include:

• Feeling like your heart is pounding
• Feeling dizzy
• Shortness of breath

What can help

If you have symptoms of a fast heartbeat When taking Benadryl, talk to your doctor. They may recommend that you take a lower dose of medication to treat your symptoms. Or they may recommend another medicine for you.

Blurry vision

Benadryl dries out your body, which can lead to blurry vision. This is the more common side effect of Benadryl.

What can help

If you have blurred vision from taking Benadryl, talk to your doctor or pharmacist. They may recommend ways to reduce this side effect. They may also suggest another medication to treat your symptoms.

Until your eyesight is clear, you should not drive or operate machinery.

Memory loss or dementia

Taking Benadryl may cause memory loss or dementia. Although rare, this side effect may be more common in older people or people who have taken the drug for a long time. Symptoms may include:

• problems speaking or finding the right words to say
• short term memory problems
• concentration problems

What can help

If you experience memory loss or dementia while taking Benadryl, talk to your doctor . They will most likely suggest that you stop taking Benadryl. They will also look for the cause of your memory loss or dementia in order to recommend the right treatment for you.

Dizziness

Dizziness is a common side effect of Benadryl. This side effect can be serious.

Until you know how Benadryl will affect you, you should not drive or operate machines after taking this medicine. If it makes you dizzy, avoid any activity until the medication wears off.

In addition, dizziness may lead to an increased risk of falling in the elderly. Falls can be very dangerous for older people.

What can help

If you get dizzy from taking Benadryl, talk to your doctor. They will recommend that you do not drive or operate machinery while you are dizzy.

They may also suggest another medicine for your symptoms that does not cause dizziness.

Allergic reaction

Like most medicines, Benadryl can cause an allergic reaction in some people. But it is not clear if this side effect occurred in studies.

Symptoms may be mild or severe and may include:

• skin rash
• itching
• redness (temporary warmth, redness, or increased skin color)
• swelling under the skin, usually on the eyelids, lips, hands or feet
• swelling of the mouth, tongue, or throat that makes breathing difficult

What may help

If you have mild symptoms of an allergic reaction, such as a mild rash, call your doctor right away. They may suggest treatment to manage your symptoms.

If your doctor confirms that you had a mild allergic reaction to Benadryl, they will decide whether you should continue using it.

If you have symptoms of a severe allergic reaction, such as swelling or difficulty breathing, call 911 or your local emergency number right away. These symptoms can be life threatening and require immediate medical attention.

If your doctor confirms that you have had a serious allergic reaction to Benadryl, he may ask you to switch to another treatment.

Tracking side effects

While on Benadryl, consider keeping a record of any side effects you experience. You can then share this information with your doctor. This is especially helpful when you first start taking new medications or using a combination of treatments.

Your side effect notes may include things like:

• what dose of the drug you were taking when you had the side effect
• how soon after starting this dose did you experience it
• specific side effect symptoms
• how it affected your daily activities
• any other medications you also took
• any other information you think is important

Vedas enenie Taking notes and sharing them with your doctor will help him learn more about how Benadryl affects you. And your doctor can use this information to adjust your treatment plan if necessary.

Benadryl Warnings

Benadryl may not be right for you if you have certain medical conditions or other factors affecting your health. Talk to your doctor about your medical history before taking Benadryl. The list below includes factors to consider.

Dementia. Benadryl can cause dementia and also worsen the symptoms of dementia in a person with this condition. If you have dementia, talk to your doctor before taking Benadryl. Instead, your doctor may recommend that you take another medicine.

Allergic reaction. If you have had an allergic reaction to Benadryl or any of its ingredients, you should not take it. Ask your doctor which other medicines are best for you.

Heart problems or high blood pressure. Benadryl may increase your heart rate and may cause more serious heart-related side effects such as heart rhythm problems. If you already have heart disease, taking Benadryl may make your condition worse. Talk to your doctor about whether it is safe for you to take Benadryl.

Liver problems. Benadryl is eliminated from your body through your liver. If your liver is not working properly, it may take longer for your body to clear the medicine. This may increase the risk of side effects. If you have any liver disease, tell your doctor before taking Benadryl.

Kidney, bladder or prostate problems. Benadryl may decrease the amount of urine you make. If you have kidney or bladder problems, you may already be producing less urine. If you have prostate problems, you may have urinary retention (inability to completely empty your bladder). These conditions may be made worse by Benadryl. If you have kidney, bladder, or prostate problems, talk to your doctor before taking this drug.

Respiratory diseases, including asthma. Benadryl dries out the nose and mouth, which reduces the symptoms of allergies or colds. This can make the mucus in your nose or mouth thicker. If you have trouble breathing, thickened mucus can make it even more difficult for you to breathe. Before you start taking Benadryl, talk to your doctor if you have any respiratory problems.

Certain eye conditions. Benadryl may increase the pressure in your eyes. If you already have a condition that increases eye pressure, taking Benadryl may make your condition worse. An example of such a condition is glaucoma. Talk to your doctor to find out if it’s safe for you to take Benadryl for your eye condition.

Drinking alcohol and Benadryl

You should not drink alcohol while you are taking Benadryl. Alcohol may increase the risk of drowsiness or dizziness. It can also cause more serious side effects such as difficult or slow breathing.

If you drink alcohol, talk to your doctor about other medicines you may be taking to treat your cold or allergy symptoms.

Pregnancy and lactation while taking Benadryl

It is generally safe to take Benadryl during pregnancy. Benadryl does not appear to increase the risk of fetal harm.

And taking small doses of Benadryl for a short time may be safe while breastfeeding.

But Benadryl passes into breast milk and may also reduce milk production.

If you are breastfeeding and taking high doses of Benadryl, this may increase your child’s risk of side effects. This is also the case if you are taking the drug for a long time.

High doses or long-term use of Benadryl may also reduce breast milk production.

If you are pregnant or planning to become pregnant, talk to your doctor about the safety of Benadryl for you and your baby. Also talk to your doctor about this if you are breastfeeding or planning to breastfeed.

What to ask your doctor

Most of the side effects of Benadryl are minor, and some people may not experience any side effects at all. In some rare cases, the drug may cause serious side effects.

Before taking Benadryl, be sure to talk to your doctor about whether the drug is safe for you. Some questions you may want to ask about Benadryl side effects include:

• How can I reduce the risk of side effects from Benadryl?
• How long can I take Benadryl for my condition without increasing the risk of side effects?
• If I have serious side effects from Benadryl, what other medicines can I use instead?

If you are using Benadryl for allergies, subscribe to the Drink-Drink allergy and asthma newsletter for tips on how to avoid triggers and manage your condition.

Ask a pharmacist

Q:

Do other medicines I take increase the risk of side effects from Benadryl?

Anonymous

A:

Yes, they can. Taking Benadryl with certain medications increases the risk of side effects. Examples of such drugs include:

• anticholinergics such as Ditropan XL (oxybutynin)
• antidepressants such as Celexa (citalopram) and Zoloft (sertraline)
• benzodiazepines such as Xanax (alprazolam) and Ativan (lorazepam)
• opioids such as Zohydro (hydrocodone) and Roxycodone (oxycodone)

Talk to your doctor or pharmacist before taking Benadryl. Based on other medicines you may be taking, they can tell you if the risk of side effects from taking Benadryl will increase.

Melissa Badowski, PharmD, MPH, FCCP Answers represent the views of our medical experts. All content is for informational purposes only and should not be considered medical advice.

Registration data: Drink-Drink has made every effort to ensure that all information is accurate, complete and up to date. However, this article should not be used as a substitute for the knowledge and experience of a licensed healthcare professional. You should always check with your doctor or other healthcare professional before taking any medication. The drug information contained herein is subject to change and is not intended to cover all possible uses, directions, precautions, warnings, drug interactions, allergic reactions, or side effects. The absence of warnings or other information for a given medicinal product does not mean that the drug or combination of drugs is safe, effective, or suitable for all patients or for all specific uses.

How long does Benadryl take to work (and why)? –

Last updated: December 2, 2022 / author
Sandeep Bhandari

/ Fact verified / 4 minutes

Exact answer: up to 1 hour

Benadryl or diphenhydramine is a first-generation antihistamine primarily used to treat symptoms of allergies, colds, or hay fever. Symptoms may include sneezing, itching, watery eyes, and a runny nose. It can also be used to treat insomnia, Parkinson’s tremors, and nausea.

Summary

Toggle

Diphenhydramine also has local anesthetic properties, which is useful for patients suffering from allergies caused by the use of other commonly used anesthetics. However, this is not a drug use label. Benadryl can also cause allergic reactions in some people. In such a case, the use of Benadryl should be avoided.

How long does Benadryl take to work?

Benadryl works quickly and may take up to an hour to achieve maximum effect. It is taken orally in the form of tablets, which allows it to be easily distributed in the body. You may notice effects within 20-30 minutes, although it should continue to work for about four to six hours.

Benadryl primarily works by neutralizing h2 (histamine 1) receptors present on airway smooth muscle and other cells such as vascular endothelial cells, gastrointestinal (GIT), cardiac tissue, immune cells, uterus and central nervous system neurons. nervous system. nervous system (CNS) of your body. As a result, Benadryl may make you dizzy. Other side effects of the medication may include heart palpitations and dry mouth.

Total:

Benadryl can also be taken in the form of an injection when the oral form is not appropriate. In this form, it has a fast-acting mechanism. When used at night before bed, the dose of Benadryl should not exceed 50 mg. For the elderly, a lower dose is preferred to avoid subsequent side effects.

Why does Benadryl work fast?

Benadryl antagonizes the h2 receptors in your body and acts as an inverse h2 receptor agonist. It reduces the symptoms of an allergic reaction by reversing the effect of histamine on your capillaries.

The h2 receptor is also similar to muscarinic receptors, due to which Benadryl also acts as an antimuscarinic agent that can be used to treat parkinsonism. It also blocks intracellular sodium channels in your body, resulting in local anesthetic properties.

There are also other medicines that can interact with Benadryl, decreasing or increasing its effect, or by manipulating how long the medicine lasts. You may consult your doctor if you are taking other medications or want to control the effect and mode of action of Benadryl. Alcohol has also been shown to increase the sedative effects of Benadryl, so alcohol intake should be controlled while taking the medication.

A few tips to enhance the effect of Benadryl:

1. It can be taken before or after meals.
2. Take exactly as directed by your doctor. Do not exceed recommended.
3. If you are using it to treat motion sickness or related symptoms, take Benadryl at least 30 minutes before motion exposure. Take doses either before meals or at night before bed for best effect.
4. It should not be used in children under the age of twelve to induce sleep. It should not be used in infants at all and should be kept away, especially from premature babies. In children, Benadryl can cause many side effects. Therefore, check with your doctor before allowing your child to use Benadryl.
5. If you use Benadryl for a long period of time, take care of your oral hygiene.
6. If you experience symptoms such as hallucinations, palpitations, drowsiness, muscle tremors, vomiting, or diarrhea, seek emergency medical attention.
7. The use of Benadryl during pregnancy should be avoided as there are no adequate studies in pregnant women. Consult your doctor before starting medication.

If you are between the ages of 18 and 60, you may experience the side effects of Benadryl, such as drowsiness, low blood pressure, headache, rapid heartbeat, incoordination, abdominal discomfort, and thick mucus in the nostrils. . Not suitable for breastfeeding women and the elderly.

It is also not suitable for people with respiratory conditions such as narrow angle glaucoma, asthma, peptic ulcers, intestinal obstruction or heart disease, high thyroid levels, enlarged prostate or constricted bladder. An overdose of Benadryl can cause hallucinations, convulsions, and can also be fatal.

Conclusion

Benadryl takes 15 to 30 minutes to work, but you may experience its peak effect in about an hour. A dose of 25 to 50 milligrams has been suggested for its sedative effect. If you experience any health problems while taking Benadryl, see your doctor as soon as possible. It is best to keep Benadryl away from pregnant women, the elderly, and children until directed by a doctor. There are herbal remedies that have the same effect as antihistamines. Instead, you can use these remedies to avoid the side effects of Benadryl.

Recommendations

1. https://nyaspubs.onlinelibrary.wiley.com/doi/abs/10.1111/j.1749-6632.1950.tb39907.x
2. https://www.jacionline.org /article/0021 -8707(46)-4/pdf

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Sandeep Bhandari

Sandeep Bhandari is the founder of ExactlyHowLong.com.

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