Diphenhydramine (Benadryl)

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Diphenhydramine (Tradename: Benadryl) is an antihistamine mainly used to treat allergies. It is also used for insomnia, symptoms of the common cold, tremor in parkinsonism, and nausea. It is used by mouth, injection into a vein, and injection into a muscle. Maximal effect is typically around two hours after a dose and effects can last for up to 7 hours.