The generic name of this medication is diphenhydramine and brand names are Benadryl, Genahist, Sominex, Unisom and Ben-Rex. The active ingredient of this medication is diphenhydramine hydrochloride. This medication is an antihistamine used to relieve symptoms of allergy, hay fever and the common cold.

Diphenhydramine hydrochloride (trade name Benadryl is produced by J&J or Dimedrol outside the U.S. Nytol as a sleeping pill) is an over-the-counter (OTC) antihistamine, sedative and hypnotic. It may also be used for the treatment of extrapyramidal side effects of typical antipsychotics. It is a member of the ethanolamine class of antihistaminergic agents. The brand Benadryl is currently trademarked in the United States by Pfizer; however, many drug store chains and retail outlets manufacture less-costly generic versions under their own store brands, often sold in boxes that share similarities in packaging size, colors and appearance of the Pfizer pill.