Diphenhydramine

Diphenhydramine is suitable for most people aged 16 or over, and sometimes children under 16, but always check first.

Diphenhydramine is not suitable for some people. For example, check with your doctor if you have lung, kidney or liver problems or epilepsy.

Diphenhydramine comes as tablets, a liquid that you swallow or a cream. Follow the instructions that come with your medicine.

Side effects of diphenhydramine include feeling sleepy or dizzy and a dry mouth. More serious side effects can happen in rare cases.

Most adults and young people aged 16 years old and above can take diphenhydramine.

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 tablets and liquid containing diphenhydramine to children aged 6 years and over.

For allergy symptoms, you can give diphenhydramine to children aged 12 years and over.

Check with your pharmacist or doctor to make sure a product is suitable for your child.

You can also use diphenhydramine cream on children aged 6 years and over for:

• insect bites and stings
• eczema

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.

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 a stomach ulcer
• have kidney or liver problems
• have problems peeing or emptying your bladder
• have epilepsy or any other health problem that causes seizures or fits
• have myasthenia gravis (a rare condition that causes muscle weakness)
• are older and have confusion
• are due to have an allergy test, as 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

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

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

Dosage for short-term insomnia

Diphenhydramine comes as 25mg and 50mg tablets for insomnia. The usual dose is 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 for hay fever and other allergies. 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 and stings or eczema

Diphenhydramine comes as a cream for insect bites and stings or eczema, 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

Put a small amount of diphenhydramine cream 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.

Wash your hands afterwards, unless you're treating your hands.

These common side effects of diphenhydramine happen in more than 1 in 100 people. There are things you can do to help cope with them:

Drowsiness usually wears off around 8 hours after a dose. Do not drive, ride a bike or use tools or machinery if you're feeling this way.

Chew sugar-free gum or suck sugar-free sweets.

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 diphenhydramine and speak to a pharmacist or your doctor.

Do not drive or ride a bike if you're feeling dizzy, unsteady or unable to concentrate.

This side effect can happen with diphenhydramine cream.

Use a high factor sunscreen (at least SPF 30), stay out of strong sun, and wear clothing that covers your skin such as long sleeves and a hat.

If you get a new skin rash or eczema where you've used the cream, or you already have eczema and it gets worse, stop using diphenhydramine and speak to a doctor.

Speak to a doctor or pharmacist if the advice on how to cope does not help and a side effect is still bothering you or does not go away.

Diphenhydramine can be used during pregnancy, but it's not normally recommended. This is because of the side effects of feeling drowsy during the day and feeling dizzy, which may be worse during pregnancy.

Talk to your doctor or pharmacist about other antihistamines, such as chlorphenamine, that may be more suitable.

If you have difficulty sleeping while you're pregnant, your doctor or midwife will be able to suggest ways to improve your sleep.

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

If your baby is healthy, you can take diphenhydramine tablets or liquid while you're breastfeeding.

Diphenhydramine passes into breast milk in very small amounts. Your baby is unlikely to get side effects. However it's better to only take it occasionally, or for a short time, as it could make them sleepy. Other non-drowsy medicines might be better, especially if you need to take it for a longer time.

Medicines containing diphenhydramine that you buy from a pharmacy may also contain other ingredients. Check with a pharmacist or doctor first if you're breastfeeding.

It's OK to use diphenhydramine cream if you're breastfeeding. It's not thought to pass into breast milk, or cause any side effects in breastfed babies. Take care that your baby does not touch any areas of your body where you've used it. Wash your hands after you have used it and before picking up your baby.

It's very rare for breastfed babies to have side effects from medicines you're taking. But it's important to keep monitoring your baby if you're taking any medicine while breastfeeding.

Contact your healthcare professional or call 111 as soon as possible if your baby:

• is not feeding as normal, or not waking to feed
• seems unusually sleepy
• is being irritable

If your baby has any symptoms that are not listed, or if you're worried about them, you can also call 111 or contact any healthcare professional.

Keep breastfeeding as usual until you've got advice about your baby's symptoms.

It's important not to share a bed with your baby while you're taking diphenhydramine tablets or liquid.

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 any other medicines, including:

• antidepressants, such as venlafaxine, tricyclic antidepressants (such as amitriptyline) or monoamine oxidase inhibitors (such as phenelzine), or if you have stopped taking these within the past 2 weeks
• any medicines to treat anxiety (such as diazepam) or to help you sleep better
• metoprolol, a heart medicine
• any other antihistamines
• any other 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

These are not all the medicines that may cause problems if you take them with diphenhydramine. For a full list, see the leaflet inside your medicine packet.

Taking diphenhydramine with painkillers

You can take diphenhydramine together with painkillers such as paracetamol or ibuprofen.

But if you're taking a cough or cold remedy containing diphenhydramine, check carefully what the other ingredients are. This is because some diphenhydramine products already contain a painkiller. Do not take extra painkillers if they do, as there's a risk of overdose.

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

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 use machinery or tools if this happens to you.

Ask your pharmacist for advice before you take this medicine together with any other painkillers or medicines.