Diphenhydramine

Diphenhydramine ( /ˌdaɪfɛnˈhaɪdrəmiːn/; abbreviated DPH, sometimes DHM) is a first-generation antihistamine possessing anticholinergic, antitussive, antiemetic, and sedative properties which is mainly used to treat allergies. Like most other first-generation antihistamines, the drug also has a powerful hypnotic effect, and for this reason is often used as a non-prescription sleep aid; especially in the form of diphenhydramine citrate. It is produced and marketed under the trade name Benadryl by McNeil-PPC (a division of Johnson & Johnson) in the U.S., Canada and South Africa (other trade names in other countries: Dimedrol, Daedalon). It is also available as a generic or store brand medication. It is also found in the name-brand products Nytol, Unisom, Tylenol PM, Excedrin PM, Midol PM, Zzzquil and Advil PM, though some Unisom products contain doxylamine instead. It is available as an over-the-counter (OTC) or prescribed HCl injectable. It may also be used for the treatment of extrapyramidal side-effects of many antipsychotics, such as the tremors that haloperidol can cause. In addition, injectable diphenhydramine can be used for life-threatening reactions (anaphylaxis) to allergens such as bee stings, peanuts, or latex, rather than risking the side-effects of epinephrine. It is a member of the ethanolamine class of antihistaminergic agents.