High Quality Content by WIKIPEDIA articles! Diphenhydramine hydrochloride is a chemical mainly used as an antihistamine, antiemetic, sedative, and hypnotic. It is produced and marketed under the trade name Benadryl by McNeil-PPC (a division of Johnson & Johnson) in the U.S. and Canada, and Dimedrol in other countries. It is also found in the name-brand products Nytol, Unisom, and Advil PM though some Unisom products contain doxylamine instead. It is available as an over-the-counter (OTC) or prescribed HCI injectable. It may also be used for the treatment of extrapyramidal side effects of typical antipsychotics, such as the tremors that haloperidol can cause. Additionally, 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. Diphenhydramine was one of the first known antihistamines, invented in 1943 by Dr. George Rieveschl, a former professor at the University of Cincinnati. In 1946, it became the first prescription antihistamine approved by the U.S. Food and Drug Administration (FDA).