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 is an antihistamine and is used to treat sneezing, runny nose, itching and other allergies. Learn about side effects, interactions and indications. Benadryl, a common antihistamine, can cause serious side effects like sedation, confusion, and even cardiac arrest, especially at high doses. Understanding these risks is crucial for safe use. 1 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 Benadryl (diphenhydramine) is a liquid medication that treats the symptoms of allergies and allergic reactions. Benadryl allergy medicine for adults and children 6+ years is formulated with 25 mg diphenhydramine HCl for respiratory relief; use product only as directed. These antihistamine tablets deliver powerful allergy and cold relief, where cold relief specifically refers to the temporary relief of runny nose and sneezing due to the common cold. Benadryl antihistamine tablets and Benadryl children’s allergy medicine is formulated with diphenhydramine HCl for clinically-proven allergy relief What symptoms does Benadryl treat? Benadryl provides relief from runny nose, sneezing, itchy, watery, eyes, and itching of the nose or throat due to allergies. What is the dosage amount? Find yourself needing help relieving allergies or a pesky itch? Check out the many allergy and itch relief products from BENADRYL® that may provide relief. 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. Diphenhydramine, also known by the brand name Benadryl, is an over-the-counter antihistamine used to relieve allergy or common cold symptoms in adults and children. It comes as pills and a liquid and is typically taken by mouth every 4 to 6 hours as needed. Because it can make you drowsy, some people also use it as a sleep aid at bedtime. Common side effects include sleepiness, dizziness, and.