Diphenhydramine: drowsy (sedating) antihistamine – NHS

1. About diphenhydramine

Diphenhydramine is an antihistamine medicine that relieves the symptoms of allergies. It’s known as a drowsy (sedating) antihistamine and is more likely to make you feel sleepy than other antihistamines. It’s used for:

• short-term sleep problems (insomnia), including when a cough, cold or itching is keeping you awake at night
• cough and cold symptoms
• hay fever
• eczema, hives (urticaria) and insect bites and stings

You can buy diphenhydramine from pharmacies and it is also available on prescription.

It comes as tablets and a liquid that you swallow. For skin allergies like hives or bites and stings it’s also available as a cream. The cream is much less likely to make you feel sleepy than the tablets or liquid.

You can also buy it mixed with other medicines, such as levomenthol, paracetamol and pseudoephedrine, to treat cough and cold symptoms.

2. Key facts

• To help you sleep, you’ll usually take diphenhydramine 20 minutes before you go to bed. It normally takes about 30 minutes to work.
• Common side effects include feeling sleepy, dizzy or unsteady on your feet. You may also have difficulty concentrating and have a dry mouth.
• You can become dependent on diphenhydramine if you take it continuously for a period of time. It may also stop working as well. Speak to your doctor if you need to take it for more than 2 weeks.
• Do not drink alcohol while taking diphenhydramine. Alcohol increases the risk of side effects.
• When diphenhydramine is mixed with other medicines, brand names include Benylin Chesty Coughs, Benylin Children’s Night Coughs, Covonia Night Time Formula, Panadol Night Pain and Unicough.

3. Who can and cannot take diphenhydramine

Diphenhydramine can be taken by most adults and young people aged 16 years and above. You can sometimes give diphenhydramine to children, depending on their age and their symptoms. Ask your pharmacist for advice.

Giving diphenhydramine to children

For cough and cold symptoms, you can give diphenhydramine tablets and liquid to children over the age of 6. For allergy symptoms, you can give it to children over 12. Check with your pharmacist or doctor to make sure a product is suitable for your child.

You can also use diphenhydramine cream on children for:

• insect bites and stings
• eczema

Important:
Warning for children

Do not give your child diphenhydramine to help them get to sleep. Diphenhydramine is only suitable for sleep problems in people aged 16 years and above.

Who may not be able to take diphenhydramine

Diphenhydramine is not suitable for some people. To make sure it’s safe for you, tell your doctor or pharmacist if you:

• have ever had an allergic reaction to diphenhydramine or any other medicine
• have lung problems, such as asthma or chronic obstructive pulmonary disease (COPD), or an illness that creates a lot of phlegm
• have an eye problem called primary angle closure glaucoma
• have a blockage in your stomach or gut
• have kidney or liver problems
• have problems peeing or emptying your bladder
• have epilepsy or any other health problem that causes fits (seizures)
• are due to have an allergy test – diphenhydramine can affect your results, so you may need to stop taking it a few days before your test – ask a pharmacist or your doctor for advice
• are unable to have any alcohol – some liquid diphenhydramine products contain a small amount of alcohol, so check the ingredients and the packaging carefully

4.

How and when to take or use diphenhydramine

If you or your child have been prescribed diphenhydramine, follow your doctor’s instructions about how and when to take it.

Only take or use diphenhydramine when you need it, for example if you’re unable to sleep because you’re worrying about something or your cold symptoms are keeping you awake.

If you’ve bought diphenhydramine or any medicine containing diphenhydramine from a pharmacy, follow the instructions that come with the packet, or ask a pharmacist for advice.

The instructions will be different depending on the type of medicine you buy, and the other medicines it’s mixed with.

Dosage

If you’re aged over 65, start with the lower dose, as you may be more likely to get side effects.

The usual dose depends on the type of diphenhydramine medicine you’re taking, and why.

Dosage for short-term insomnia

Diphenhydramine comes as 25mg and 50mg tablets. You’ll usually take 50mg, 20 minutes before you go to bed.

Dosage for cough and cold symptoms

Diphenhydramine comes mixed with other medicines to treat the symptoms of coughs and colds. It comes as tablets and as a liquid that you swallow. The usual dose depends on the type of medicine you’re taking. Check the instructions on the packaging carefully, or ask your doctor or pharmacist if you’re unsure.

Dosage for hay fever and allergies

Diphenhydramine comes as 25mg and 50mg tablets. The usual dose is 25mg or 50mg, taken 3 or 4 times a day. Try to space your doses evenly throughout the day.

Dosage for insect bites, stings and eczema

Diphenhydramine comes as a cream which you use once or twice a day. You’ll only need a small amount, enough for a thin layer.

How to take or use it

You can take diphenhydramine tablets and liquid with or without food.

How to take diphenhydramine tablets

Always take your diphenhydramine tablets with a drink of water. Swallow them whole. Do not chew them.

How to take diphenhydramine liquid

Liquid medicines containing diphenhydramine come with a plastic syringe or spoon to help you measure the right dose. If you do not have a syringe or spoon, ask your pharmacist for one. Do not use a kitchen teaspoon as it will not measure the right amount.

How to use diphenhydramine cream

With the cream, put a small amount onto the affected area and smooth it in gently. Do not use it on large areas of skin. Keep the cream away from your eyes, mouth and nose. Remember to wash your hands afterwards, unless you’re treating your hands.

What if I forget to take or use it?

If you’re taking diphenhydramine to help you sleep and you forget to take it by bedtime, skip your missed dose and start again the next evening.

If you’re taking any other medicine containing diphenhydramine and forget to take a dose, take your medicine when you next need it to ease your symptoms.

Never take 2 doses at the same time. Never take an extra dose to make up for a forgotten one.

If you forget doses often, it may help to set an alarm to remind you. You could also ask your pharmacist for advice on other ways to help you remember to take your medicine.

What if I take or use too much?

Too much diphenhydramine can be dangerous.

If you’ve taken more than the usual dose you may:

• feel very sleepy
• feel sick (nauseous)
• get blurry eyesight
• feel your heart beating very fast

In serious cases you can become unconscious and may need emergency treatment in hospital.

Do not use diphenhydramine cream at the same time as other products containing diphenhydramine. This can lead to overdose.

Urgent advice: Contact 111 for advice if:

• you take more than your prescribed dose of diphenhydramine

Go to 111.nhs.uk or call 111

If you need to go to A&E, do not drive yourself. Get someone else to drive you or call for an ambulance.

Take the diphenhydramine packet or leaflet inside it plus any remaining medicine with you.

5. Side effects

Like all medicines, diphenhydramine can cause side effects, although not everyone gets them. However, you may be more likely to get them if you’re over 65.

Common side effects

Common side effects happen in more than 1 in 100 people. Talk to your doctor or pharmacist if these side effects bother you or do not go away:

• feeling sleepy, or drowsy, during the daytime
• dry mouth
• feeling dizzy or unsteady on your feet, or having difficulty concentrating

Diphenhydramine cream can sometimes make your rash worse. It may also make your skin sensitive to sunlight.

Serious side effects

Urgent advice: Contact 111 for advice now if:

• you have a fast or irregular heartbeat (palpitations)
• you feel any numbness or pins and needles
• you feel confused or very restless

Immediate action required: Call 999 if:

• you or child has had a seizure or fit

Serious allergic reaction

In rare cases, it’s possible to have a serious allergic reaction (anaphylaxis) to diphenhydramine.

Immediate action required: Call 999 or go to A&E now if:

• you get a skin rash that may include itchy, red, swollen, blistered or peeling skin
• you’re wheezing
• you get tightness in the chest or throat
• you have trouble breathing or talking
• your mouth, face, lips, tongue or throat start swelling

You could be having a serious allergic reaction and may need immediate treatment in hospital.

Other side effects

These are not all the side effects of diphenhydramine. For a full list, see the leaflet inside your medicine packet.

Information:

You can report any suspected side effect using the Yellow Card safety scheme.

Visit Yellow Card for further information.

6. How to cope with side effects of diphenhydramine

What to do about:

• feeling sleepy, or drowsy, during the daytime – drowsiness usually wears off 8 hours after a dose. Do not drive, ride a bike or use tools or machinery if you’re feeling this way.
• dry mouth – chew sugar-free gum or suck sugar-free sweets.
• feeling dizzy or unsteady on your feet, or difficulty concentrating – if diphenhydramine makes you feel this way, stop what you’re doing and sit or lie down until you feel better. If the feeling does not go away or is worrying you, do not take any more medicine and speak to a pharmacist or your doctor.

7. Pregnancy and breastfeeding

Diphenhydramine and pregnancy

While diphenhydramine can be used during pregnancy, it is not normally recommended. This is because of the side effects, which may be more significant during pregnancy. Discuss with your doctor or pharmacist other medicines, such as chlorphenamine, that may more suitable.

If you have difficulty sleeping while you’re pregnant, your doctor or midwife may suggest ways to improve your sleep routine, like relaxing, and avoiding naps.

If you have a cough or cold, you can help to ease your symptoms by resting, drinking plenty of fluids and taking paracetamol.

Diphenhydramine and breastfeeding

If your doctor or health visitor says your baby is healthy, you can take diphenhydramine while you’re breastfeeding, but it’s better to take occasional doses or only take it for a short time.

Diphenhydramine passes into breast milk in very small amounts. Although it’s unlikely to cause any side effects in your baby, it is a drowsy antihistamine, so could make your baby sleepy.

If you’re breastfeeding, or planning to breastfeed, talk to your doctor. They may recommend similar antihistamines, called loratadine and cetirizine, that are more suitable while you’re breastfeeding.

Talk to your doctor, pharmacist, midwife or health visitor if your baby is not feeding as well as usual, seems unusually sleepy, seems irritable, or if you have any other concerns about your baby.

Non-urgent advice: Tell your doctor if you’re:

• trying to get pregnant
• pregnant
• breastfeeding

8. Cautions with other medicines

Some medicines can affect the way diphenhydramine works, and increase the chances of you having side effects. Check with your pharmacist or doctor if you’re taking:

• antidepressants, such as venlafaxine or a monoamine oxidase inhibitor such as phenelzine
• metoprolol, a heart medicine
• any medicine that makes you drowsy, gives you a dry mouth, or makes it difficult for you to pee – taking diphenhydramine might make these side effects worse

If you’re taking a cough or cold remedy or a painkiller containing diphenhydramine, check carefully what the other ingredients are. For example, check whether it contains paracetamol. Ask your pharmacist for advice before you take this medicine together with any other painkillers or medicines.

Mixing diphenhydramine with herbal remedies and supplements

There might be a problem taking some herbal remedies and supplements alongside diphenhydramine, especially ones that cause side effects such as sleepiness, a dry mouth or making it difficult to pee.

Important:
Medicine safety

Tell your doctor or pharmacist if you’re taking any other medicines, including herbal medicines, vitamins or supplements.

9. Common questions about diphenhydramine

How does diphenhydramine work?

Diphenhydramine is a medicine called an antihistamine. It is classed as a drowsy (sedating) antihistamine.

When you come into contact with something you’re allergic to, your body produces a chemical called histamine. This can cause symptoms such as a runny nose or skin rashes.

Diphenhydramine blocks the effects of histamine in your brain and this reduces symptoms. It enters the brain in large quantities and this can make you feel drowsy.

Diphenhydramine also blocks the effects of another chemical called acetylcholine. This can help a cough or runny nose but can also cause side effects such as a dry mouth and dry nose.

How long does it take to work?

If you’re taking diphenhydramine for short-term sleep problems, it will start to make you feel drowsy around 20 to 30 minutes after you take it.

For coughs and colds, your symptoms will normally start to improve within 20 minutes.

The medicine should work for around 4 to 6 hours.

How long can I take it for?

Only take diphenhydramine for a short time.

You can become dependent on it if you take it continuously for too long. To avoid this, follow the instructions that come with the medicine and only take diphenhydramine for a very short time, unless your doctor advises otherwise.

Is diphenhydramine addictive?

It is unlikely that you’ll become addicted to diphenhydramine but it’s best to only take it for a short time. You can become dependent on diphenhydramine if you take it continuously for too long.

Follow the instructions that come with the medicine and only take diphenhydramine for a very short time, unless your doctor advises otherwise.

Can I take more than one antihistamine at a time?

If you have a severe itchy skin rash, your doctor may recommend taking 2 different antihistamines at the same time for a few days.

As well as taking a non-drowsy antihistamine during the day (such as fexofenadine, cetirizine or loratadine), your doctor may advise that you take a drowsy antihistamine at night if itching is making it difficult to sleep.

Do not take another drowsy antihistamine together with diphenhydramine. It will make you very tired and sleepy. Other drowsy antihistamines include chlorphenamine (Piriton), promethazine (Phenergan) and hydroxyzine (Atarax or Ucerax).

Important

Do not take 2 antihistamines together unless you’ve been advised to by your doctor.

What’s the difference between diphenhydramine and other antihistamines?

Diphenhydramine is known as a drowsy, or sedating, antihistamine as it makes you sleepy.

Non-drowsy antihistamines are less likely to have this effect. These include cetirizine, fexofenadine and loratadine.

Most people prefer to take a non-drowsy antihistamine as it’s less likely to interfere with their everyday routine. You might choose to take a drowsy antihistamine, however, if you’re having problems falling asleep, or if symptoms like itching or coughing are keeping you awake.

There is not enough information to say whether one antihistamine is better than another for treating allergies. You may need to try a few different medicines to find what works best for you. Ask your pharmacist or doctor for advice if you’re unsure.

How is it different to other cough and cold remedies?

Diphenhydramine blocks the effects of a natural chemical called acetylcholine. This can help dry up a cough or runny nose but can also cause side effects such as a dry mouth and dry nose.

Some cough and cold remedies claim to suppress your cough or stop you bringing up phlegm. Although some people find them helpful, they’re not usually recommended. This is because there’s little evidence that they’re any more effective than simple home remedies, and they’re not suitable for everyone.

Can I take it with painkillers?

Yes, you can take diphenhydramine together with painkillers such as paracetamol or ibuprofen.

If you take diphenhydramine with painkillers that contain codeine (such as co-codamol) or other prescription painkillers, you may feel very tired and sleepy. Do not drive, ride a bike or operate machinery or tools if this happens to you.

It’s important to check the packaging or label of your medicine carefully. This is because some diphenhydramine products already contain a painkiller. Do not take extra painkillers if this is the case, as there’s a risk of overdose.

Speak to your pharmacist if you’re not sure whether a medicine already contains a painkiller.

Can I drive or ride a bike with it?

Do not drive a car or ride a bike if diphenhydramine makes you sleepy during the day, gives you blurred vision or makes you feel dizzy, clumsy or unable to concentrate or make decisions. This may be more likely when you first start taking diphenhydramine but could happen at any time, for example when starting another medicine.

It’s an offence to drive a car if your ability to drive safely is affected. It’s your responsibility to decide if it’s safe to drive. If you’re in any doubt, do not drive.

Talk to your doctor or pharmacist if you’re unsure whether it’s safe for you to drive while taking diphenhydramine. GOV.UK has more information on the law on drugs and driving.

Will it affect my fertility?

There’s no evidence to suggest that taking diphenhydramine reduces fertility in either men or women.

Will it affect my contraception?

Diphenhydramine does not affect any type of contraception including the combined pill and emergency contraception.

Can I drink alcohol with it?

Do not drink alcohol while you’re taking diphenhydramine.

Alcohol and diphenhydramine together can make you sleep very deeply. You will not be able to breathe properly and you may have difficulty waking up.

Is there any food or drink I need to avoid?

You can eat normally while taking diphenhydramine.

However, do not drink alcohol. If you are taking diphenhydramine to help you sleep, you should also try not to drink anything that contains caffeine, such as coffee, tea, cola or energy drinks. Caffeine has the opposite effect to diphenhydramine on your body and can stop it working.

Does diphenhydramine make you put on weight?

There’s no evidence that diphenhydramine makes you put on weight.

Can lifestyle changes help me sleep better?

There are a number of things you can try to help yourself have a good night’s sleep:

• set regular times for going to bed and waking up
• relax before bedtime – try taking a warm bath or listening to calming music
• use thick curtains or blinds, an eye mask and earplugs to stop you being woken up by light and noise
• avoid caffeine, cigarettes or vapes, alcohol, heavy meals and exercise for a few hours before bedtime
• do not watch TV or use phones, tablets or computers in bed, or before bedtime
• do not nap during the day
• make a list of your worries and any ideas for how to solve them before you go to bed – this can help you forget about them until the morning

Can lifestyle changes help with hay fever and other allergies?

If you have hay fever, it will help if you do not spend too much time outside when the pollen count is high.

Tips for when you’re outside

• Do not cut grass or walk on grass.
• Wear wraparound sunglasses to stop pollen getting into your eyes.
• Put Vaseline (petroleum jelly) around your nostrils to help trap pollen.
• Shower and change your clothes after you’ve been outside to wash off pollen.

Tips for when you’re inside

• Keep windows and doors shut as much as possible.
• Vacuum regularly and dust with a damp cloth.
• Do not keep fresh flowers in the house.
• Do not smoke or be around smoke because it makes hay fever symptoms worse.

The best way to prevent any sort of allergic reaction is to avoid the substance that you’re allergic to, if you can. There are some practical steps you can follow to help you avoid common allergens.

Diphenhydramine Dosing Table – HealthyChildren.org

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Safety & Prevention

Safety & Prevention

​Diphenhydramine (also known as Benadryl®) is a medicine used to treat allergic reactions, hives and allergies that affect the nose (called nasal allergies).

It is an “over-the-counter” medicine, meaning that you can get it without a doctor’s prescription. There are other medicines like diphenhydramine that might be safer for young children.

The table* below can help you figure out the right amount of diphenhydramine to give. Use your child’s weight to decide on the right amount. You can find the weight in the top row of the chart.

*Table notes:

• Age of child: Do not give diphenhydramine to children less than 6 years of age unless your child’s doctor tells you to. There are other medicines that are like diphenhydramine but will not make your child sleepy (like loratadine, cetirizine, fexofenadine) that can be bought without a prescription and are safer for young children.
• Measuring the dose for liquid medicines (should be in “mL” or metric units): It is easier to give the right amount of medicine when using a syringe than when using a kitchen teaspoon or tablespoon. Use the tool that comes with the medicine. If a tool does not come with the medicine, ask your pharmacist for one.
• How often to give the medicine (frequency): You can give diphenhydramine every 6 hours as needed.
• Adult dose: 50 mg
• Side effects: This medicine can make a child sleepy. Some children, however, may get more excited and active instead of getting sleepy. Because this medicine can make people sleepy, it is important to be careful when driving or using heavy machines after taking this medicine. This is especially important for teens who are driving.

More information

• How to Use Liquid Medicines for Children
• Using Over-the-Counter Medicines With Your Child
• AAP Allergy Tips
• Create an Allergy and Anaphylaxis Emergency Plan

Last Updated

10/21/2021

Source

American Academy of Pediatrics Council on Quality Improvement and Patient Safety (Copyright © 2021)

The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.

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 awkward
• allergic reaction*†
• rapid heartbeat* 90 034

If you develop serious side effects when taking Benadryl, contact your doctor immediately. If 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 may 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 medicine.

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 can 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 this
• specific side effect symptoms
• how it affected your daily activities
• any other medications you also took
• any other information you think is important

Vedas ing 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 medications 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.

Is Benadryl safe for long-term use in dogs?

Benadryl or diphenhydramine is an antihistamine that helps relieve allergy symptoms in both humans and animals. It can also be used to relieve the symptoms of motion sickness if the dog needs to be transported long distances. For most dogs, the appropriate dosage of Benadryl is perfectly safe.

Never give your dog too much Benadryl – an overdose is possible. Abuse of the drug can lead to fatal diphenhydramine poisoning, so always consult your veterinarian if you are unsure of the correct dosage. Signs of an overdose include constipation, agitation, dilated pupils, seizures, and rapid heartbeat.

Do not use diphenhydramine for more than 2 weeks to treat sleep problems and more than 7 days to treat cold or allergy symptoms.

In addition, long-term use of Benadryl may increase the risk of developing dementia such as Alzheimer’s disease, especially in the elderly. In one study, people over 65 who took medications such as Benadryl daily for three years or longer had an increased risk of dementia or Alzheimer’s disease.

However, older people can get confused when taking diphenhydramine because it also blocks a brain chemical called acetylcholine that plays a big role in attention and short-term memory. Taking diphenhydramine over a long period of time may actually predispose people to dementia.

The usual dosage is about 1 mg per pound two to three times a day. Veterinarians often recommend starting with half the dose to see how it calms the dog the first time. Also, pet parents should be aware that tablets and capsules are usually 25mg, but other sizes (such as 50mg) do exist.

The Merck Veterinary Manual recommends 2-4 milligrams of Benadryl per kilogram of body weight two to three times daily. However, this dosage may vary depending on your dog’s health condition.

While antihistamines can help you sleep, he says, the overall quality of sleep is usually not very good. Sometimes they even have the opposite effect and cause hyperactivity, especially in children. “Using Benadryl or any antihistamine for sleep has no long-term benefit,” Alapat said.

Drowsiness, dizziness, constipation, upset stomach, blurred vision, or dry mouth/nose/throat may occur. If any of these effects persist or worsen, tell your doctor or pharmacist immediately.

Benadryl may safely relieve allergy symptoms in children of suitable age, but should never be used as a sleep aid.

To date, studies have not conclusively proven that Benadryl (as a specific individual drug) increases the risk of dementia. However, the class of drugs to which Benadryl belongs (anticholinergics) does appear to be associated with dementia.

Diphenhydramine is classified as an anticholinergic drug and a study of this drug class found that increased use was associated with an increased risk of dementia of up to 54% [2].

Generally, antihistamines do not cause kidney problems. Some, such as diphenhydramine (Benadryl), can cause urinary retention in the bladder. Others, such as Claritin and Zyrtec, are generally very safe.

People who are trying to stop using Benadryl for sleep are advised to reduce it so that these effects are less uncomfortable.