Find out how much Benadryl adults and children can safely take, plus essential safety tips and side effects to watch for in this medically-reviewed guide. 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. Use BENADRYL ® Extra Strength Allergy Relief Antihistamine Tablets with 50 mg of Diphenhydramine HCl, which are over-the-counter antihistamine tablets from BENADRYL ®, for effective relief from symptoms related to hay fever or other upper respiratory allergies including runny nose, sneezing, itchy, watery eyes, and itching nose and throat as well as symptoms of common cold including sneezing. Get the facts on Benadryl’s dosages. You can also learn how to take the drug, which forms it comes in, and more. Benadryl (diphenhydramine) is an over-the-counter (OTC) antihistamine used to treat allergy symptoms, such as sneezing and runny nose. It’s safe for most adults and children ages 6 and older to take at recommended dosages. The typical adult Benadryl dosage is 1 to 2 tablets or capsules by mouth every 4 to 6 hours as needed. Adults ages 65 and older should contact a healthcare professional. 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 is an antihistamine and is used to treat sneezing, runny nose, itching and other allergies. Learn about side effects, interactions and indications. 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. Official answer: The maximum safe Benadryl (diphenhydramine) dose for adults is 50 to 100 mg for a single dose with a daily maximum of.