Diphenhydramine (Benadryl)

Allergy (H1 Antagonist, 1st Gen)

Dosing & Administration

Adult Dose

25-50 mg PO/IV/IM every 4-6 hours (max 300 mg/day).

Pediatric Dose

1-1.25 mg/kg PO/IV/IM every 6 hours (max 300 mg/day).

Renal Adjustment

Increase dosing interval in severe impairment.

Hepatic Adjustment

No specific adjustment, use caution.

Safety & Special Populations

Pregnancy Category

B

Lactation Safety

Use caution (can cause sedation in infant and decrease milk supply).

Contraindications & Adverse Effects

Contraindications

  • Neonates or premature infants
  • Nursing mothers

Common Adverse Effects

  • Sedation
  • Anticholinergic effects (dry mouth, urinary retention)
  • Paradoxical excitation in children