Benadryl (Diphenhydramine) Dosage Calculator

The standard diphenhydramine dose for children is 1-1.25 mg/kg per dose, given every 4-6 hours as needed. For children 2-5 years: 6.25 mg per dose; ages 6-11: 12.5-25 mg per dose; ages 12+: 25-50 mg per dose. Never exceed 4 doses in 24 hours.

Diphenhydramine is not recommended for children under 2 years of age without a doctor's explicit direction. Young children are at higher risk for side effects including paradoxical excitability, respiratory depression, and seizures.

Common side effects include drowsiness, dry mouth, dizziness, and constipation. In some children, it can cause paradoxical hyperactivity. Serious side effects include difficulty breathing, seizures, and cardiac arrhythmias at toxic doses.