How and when to take or use diphenhydramine - Brand names: Nytol Original, Boots Sleepeaze, Histergan

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 and how to take or use diphenhydramine

Dosage

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.

How long to take it for

Only take diphenhydramine for a short time, unless your doctor gives you different advice.

You can become dependent on diphenhydramine if you take it without a break for too long. To avoid this, follow the instructions that come with the medicine.

If you 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.

If you take or use too much

Taking too much diphenhydramine can be dangerous. It's important to get medical advice if you take more than the recommended dose.

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