Benadryl Dosing
Weight-based dosing (1 mg/kg every 6 hours, max 25 mg for children) with automatic conversion to suspension volumes or tablet counts. For allergies or acute allergic reactions.
Standard: 1 mg/kg per dose (max 25 mg).
Common OTC liquid: 12.5 mg per 5 mL.
Chewable: 12.5 mg - Capsule/Tablet: 25 mg.
Usual maximum: every 6 hours (4 doses/24 hr).
Recommended Dose
Per dose
18.0 mg
Approximately 7.2 mL (2.5 mg/mL) - Tablets: 0.72.
Daily maximum
72 mg/day
Do not exceed 150 mg/day or more than 4 doses.
How to Use This Calculator
Confirm patient age/weight
Benadryl is not recommended for infants under 2 years unless explicitly directed by a physician.
Enter concentration and tablet strengths
Liquid formulations vary globally; verify the label before dosing.
Administer and monitor
Provide dosing every 6 hours as needed. Monitor for sedation, paradoxical excitation, or anticholinergic effects.
Formula
Per dose (mg) = weight (kg) * 1 mg/kg (max 25 mg for children, 50 mg for adolescents/adults).
Based on AAP drug monographs and manufacturer dosing charts.
Frequently Asked Questions
Can I give Benadryl for sleep?
Not recommended. Use only for allergic symptoms unless advised by a pediatrician.
What if I miss a dose?
Administer when remembered if at least 6 hours since the last dose. Do not double up.
What are common side effects?
Drowsiness, dry mouth, thickened secretions. Paradoxical agitation may occur in young children.
Can I combine with other antihistamines?
Avoid combining with other antihistamines (cetirizine, loratadine) without clinician approval to prevent overdose.
Is IV Benadryl the same dose?
IV dosing is typically 1.25 mg/kg (max 50 mg). Use hospital protocols for IV administration.