Diphenhydramine
Also sold as: Benadryl
No prescription neededAllergy medicines (antihistamines)
Comes as:TabletCapsuleSyrupInjection
Usual adult dose
Usual adult dose: 25 to 50 mg every 4 to 6 hours when needed. Do not take more than 300 mg in 24 hours. Not for children under 6 years unless a doctor advises.
Your doctor may give you a different dose. Children's doses depend on weight.
Side effects
Common
- strong drowsiness
- dry mouth
- dizziness
- blurred vision
- constipation
Serious — get help
Stop taking it and see a doctor straight away if you notice:
- confusion or hallucinations
- fits
- fast or irregular heartbeat
Do not take it, or take care, if
- Glaucoma (raised eye pressure)
- Enlarged prostate or difficulty passing urine
- Young children and elderly people (use with caution)
- Do not drive or use machines; avoid alcohol
- Breastfeeding
Interactions
Medicines that can react with this one.
Moderate3 medicinesTake together only with care. Ask your doctor or pharmacist.
- Amitriptyline
Both have anticholinergic effects; more dry mouth, constipation, confusion and urine retention.
- Diazepam