Benadryl, a common antihistamine, can cause serious side effects like sedation, confusion, and even cardiac arrest, especially at high doses. Understanding these risks is important for safe use. 1 Benadryl is an antihistamine and is used to treat sneezing, runny nose, itching and other allergies. Learn about side effects, interactions and indications. Benadryl is a brand of various antihistamine medications used to treat allergies, whose content varies in different countries, but which includes some combination of diphenhydramine, acrivastine, or cetirizine. Benadryl (diphenhydramine) is a liquid medication that treats the symptoms of allergies and allergic reactions. Diphenhydramine, or Diphenylhydramine, sold under the brand name Benadryl among others, is an antihistamine and sedative. Although generally considered sedating, diphenhydramine can cause paradoxical central nervous system stimulation in some individuals, particularly at higher doses. Benadryl (Diphenhydramine) may treat, side effects, dosage, drug interactions, warnings, patient labeling, reviews, and related medications including drug comparison and health resources. Learn about diphenhydramine usage and dosing. Read the latest news and reviews about the drug as well as potential side effects and popular alternatives. Do you need help relieving allergies or a pesky itch? Check out the many allergy and itch relief products BENADRYL® offers which may help provide relief. Find BENADRYL® dosage information for adults, children, and toddlers and learn how much you and your family should take with our allergy medicine product-dosing guide. Benadryl (diphenhydramine) is a brand-name over-the-counter drug that’s used for allergies and itchy skin. Learn about side effects, price, and more. Benadryl is a brand) name for diphenhydramine hydrochloride, a sedating antihistamine used to treat allergies, sleep problems, and motion sickness. The recommended dosage of Benadryl by condition is as follows. Find patient medical information for Diphenhydramine (Benadryl, Unisom, and others) on WebMD including its uses, side effects and safety, interactions, pictures, warnings, and user ratings.