Diphenhydramine Pediatric Dosage Calculator
First-generation antihistamine dosing for allergic reactions, pruritus, and insomnia in children.
Weight in kilograms
Age in years
Clinical indication
⚠️ Warnings & Contraindications
- FDA warns against use in children <2 years for cough/cold due to risk of serious side effects
- Paradoxical excitation (hyperactivity) common in young children
- Significant anticholinergic effects: dry mouth, urinary retention, constipation
- May cause sedation and impaired school performance
- Contraindicated in angle-closure glaucoma and lower respiratory symptoms (asthma)
- Not recommended for routine insomnia in children
ℹ️ Clinical Notes
Liquid: 12.5 mg/5mL. Chewable: 12.5 mg. Tablets: 25 mg, 50 mg. For allergic reactions, may be given IV/IM in acute settings. Second-generation antihistamines (cetirizine, loratadine) preferred for chronic use.
References
- Diphenhydramine Dosage Guide - Drugs.com (2026)
- Diphenhydramine pediatric dosing - WikEM (2026)
Medical Disclaimer
This calculator is provided for educational and informational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition. Never disregard professional medical advice or delay in seeking it because of something you have read or calculated using this tool.
The authors and publishers of this calculator make no representations or warranties of any kind, express or implied, about the completeness, accuracy, reliability, suitability, or availability of the information, products, services, or related graphics contained within this tool for any purpose.