This NHS content is written for people in England. Medicine names, availability, prescribing and services may differ in other countries.
Common side effects of diphenhydramine
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:
Feeling sleepy or drowsy during the daytime
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.
Dry mouth
Chew sugar-free gum or suck sugar-free sweets.
Feeling dizzy or unsteady on your feet, or having 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 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.
Skin being more sensitive to sunlight
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.
Eczema or a skin rash
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.
View the original NHS website page ↗. Refreshed 19 August 2026.
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