Benadryl Child Dosage Chart: Weight-Based Diphenhydramine Dosing for Parents

By Kurt Hansen, MD · Emergency Physician

The drug label on children's diphenhydramine (Benadryl) groups kids by age, but kids of the same age can differ in weight by a factor of two or more — and the label still recommends a single dose. That is why emergency physicians dose by weight, not by age: a weight-based dose follows your child's actual body size and reduces the chance of under- or over-dosing. Diphenhydramine is an antihistamine that can cause sedation; it is only for children 24 months and older — younger children should not be given diphenhydramine.

The calculator below uses the standard 1.25 mg/kg pediatric diphenhydramine dose (maximum 50 mg per single dose, no more than 4 doses in 24 hours, and at least 6–8 hours between doses). Enter your child's weight, confirm the formulation you have at home, and the calculator returns the exact mL for the Children's Benadryl (diphenhydramine) 12.5 mg / 5 mL suspension in front of you.

Calculate your child's Benadryl dose

How Perfect Dose calculates doses — FAQ

Looking for a less-sedating, once-daily option? See Zyrtec Child Dosage Chart: Weight-Based Cetirizine Dosing for Parents.

Looking for the generic name? See our Diphenhydramine Child Dosage Chart.

About the Author

Kurt Hansen, MD, is an Emergency Physician and the founder of Perfect Dose App. He has counseled thousands of parents on pediatric medication dosing during more than a decade of emergency medicine practice.