Medscape - Hypersensitivity reactions, insomnia, antihistamine-specific dosing for Benadryl, Nytol (diphenhydramine), frequency-based adverse effects, comprehensive interactions. Benadryl (Diphenhydramine) Dosing and Frequency For adults and children over 12 years, the standard dose is 25-50 mg (10-20 mL) every 4-6 hours, not exceeding 6 doses in 24 hours; for children 6 to under 12 years, give 25 mg (10 mL) every 4-6 hours. 1 Benadryl starts working within 30 minutes after taking it orally, with peak effects reached in 1-2 hours. The antihistamine effects last 4-6 hours for most people. Patients should contact their healthcare provider if symptoms of insomnia persist for more than 2 weeks while receiving treatment. Oral: Prescription formulations: 25 to 50 mg orally 3 to 4 times a day, with the first dose given 30 minutes before exposure to motion and repeated before meals and upon retiring throughout the duration of the journey. Benadryl (Diphenhydramine) Dosing and Frequency For adults and children over 12 years, the standard dose is 25-50 mg every 4-6 hours (maximum 6 doses in 24 hours), while children 6-12 years receive 25 mg every 4-6 hours, and diphenhydramine should not be used in children under 6 years. 1 Adults can take Benadryl (diphenhydramine) every 4 to 6 hours as needed, with a maximum of 300 mg in a 24-hour period. That translates to 25 to 50 mg per dose, up to about 4 to 6 doses per day depending on the strength. Adults should take 1 to 2 tablets or capsules of Benadryl every 4 to 6 hours as symptoms occur. A child’s Benadryl dosage depends on their age. Adults should take 25 to 50 mg of Benadryl every four to six hours as needed. Keep these guidelines in mind: Do not use Benadryl more than six times in 24 hours. Benadryl comes in several forms: Always read the package instructions to ensure you're taking the correct dose. Adults can take Benadryl (diphenhydramine) every 4 to 6 hours as needed, up to 3 or 4 times per day. For children 6 and older, the standard interval is every 6 hours as needed. Take every 4 to 6 hours, or as directed by a doctor. Do not take more than 6 doses in 24 hours. As with any medicine, overdose, abuse, or misuse can lead to serious side effects with potentially long-lasting or even life-threatening consequences.