Benadryl is a brand of various antihistamine medications used to stop allergies, whose content varies in different countries, but which includes some combination of diphenhydramine, acrivastine, and cetirizine.

It is sold by Johnson & Johnson and is used to relieve allergy symptoms such as sneezing, itching, runny nose, rash, and hives.[1] Some forms of Benadryl are to be taken orally, while some creams and gels are to be applied to the skin.[2] Common side effects of the drug include drowsiness, dizziness, dry mouth and throat, confusion, and blurred vision.[2]

In the United States and Canada, the active ingredient is diphenhydramine. In the United Kingdom, the active ingredients of Benadryl are the antihistamines acrivastine[3] or cetirizine.[4] Benadryl is also sold as a cough medicine in Australia and New Zealand containing diphenhydramine, as well as the antitussive dextromethorphan or the expectorant guaifenesin.[5]