Diphenhydramine
BENADRYL
What it isFirst-generation H1 antagonist; allergy, insomnia, motion sickness and acute dystonia.
Why this oneIt reverses acute dystonic reactions within minutes and is available without prescription.
What limits itHeavy anticholinergic burden and sedation — it is on every deprescribing list for the elderly. Tolerance to the hypnotic effect is rapid.
FDA-approved for
- allergy (~1946)
- insomnia (~1980)
Off-label
- insomnia
- dystonia
FDA label
Read the full label on DailyMed ↗
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Nighttime pain relief / sleep aid (OTC combination) | Adults & children ≥12 yr | 2 caplets QHS | 2 caplets QHS | 2 caplets/24h |
Renal Undefined
Hepatic Undefined
Instructions
- Take at bedtime; do not exceed 2 caplets in 24 hours
- Do not use in children under 12 years
Pregnancy Undefined
Lactation Undefined
NO BOXED WARNINGS
Principal riskAnticholinergic burden; on every elderly deprescribing list
Cost, est. cash$10–$300/month
Generic entry1982
Classes and tags
Clinical profile
Legacy pregnancy categoryB
Defining liabilityLocal irritation, sensitization or administration-site injury; negligible systemic toxicity at usual use.
Mechanism of action: Diphenhydramine ballicule
Open Diphenhydramine in the interactive console ↗
Memory aids: mascots and interaction avatars
“wears two hats” – max antihistamine and antimuscarinic
