BENADRYL - A commonly used nonprescription oral antihistamine. The usual dose for adults and adolescents in the treatment of mild allergic reactions or itching is 25-50 mg orally every 4-6 hours as needed. For severe allergic reactions, may take up to 100 mg in a single dose. Consult your doctor for use in infants under 1 year. For children (1 to 6 years) give 6.25-12.5 mg every four to six hours. For severe allergic reactions give 2 mg of diphenhydramine per kilogram of body weight or 1mg of diphenhydramine per pound of body weight. For children (6-12 years) give 12.5-25 mg every four to six hours. For severe allergic reactions give 2 mg of diphenhydramine per kilogram of body weight or 1 mg of diphenhydramine per pound of body weight. Do not exceed a total of 150 mg/day.