Diphenhydramine Child Dosage Chart: Weight-Based Dosing for Parents

By Kurt Hansen, MD · Emergency Physician

Diphenhydramine is a first-generation antihistamine used for short-term allergy and itch relief, including symptoms such as hives, sneezing, and an itchy or runny nose. It can cause significant sedation, so it should never be used to make a child sleep. Diphenhydramine is only for children 24 months and older — younger children should not be given it without direct guidance from a clinician.

Pediatric diphenhydramine dosing is calculated from your child's current weight, not an age band. The standard dose is 1.25 mg/kg, with a 50 mg single-dose maximum, at least 6–8 hours between doses, and no more than 4 doses in any 24-hour period. This page covers the Children's diphenhydramine 12.5 mg / 5 mL suspension and returns the exact mL for the formulation in front of you.

This page and calculator are educational reference tools only. Always verify the product label and follow your clinician's guidance; review our medical disclaimer before using any dosing information. Seek urgent help for breathing trouble, facial or tongue swelling, severe or unusual drowsiness, a seizure, or a suspected overdose.

Calculate your child's diphenhydramine dose

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Looking for the brand-name equivalent? See our Benadryl 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.