Benadryl is a brand name for a number of different antihistamine medications used to stop allergies including diphenhydramine, acrivastine and cetirizine. In the United States and Canada, it is the first-generation antihistamine diphenhydramine. Some products marketed in Australia and New Zealand as a cough medicine with the Benadryl name contain diphenhydramine.[1] In the United Kingdom, the active component of Benadryl is often the antihistamine acrivastine[2] or cetirizine.[3] Benadryl is available for oral or topical use. It is marketed without a prescription by Johnson & Johnson subsidiary McNeil Consumer Healthcare. Before 2007, Benadryl was marketed by Pfizer Consumer Healthcare (originally Warner–Lambert).[4][5] Diphenhydramine can also cause sleepiness. The product is not recommended for use in children under the age of six[6] where it has caused fatalities.[7][8] In 2014, the FDA posted a warning about swallowing Benadryl gel products that were meant to be used topically. The warning stated that the relatively high levels of diphenhydramine in the gel could cause confusion and loss of consciousness.[9][10]

Source:Wikipedia.org