Diphenhydramine

Generic Name: diphenhydramine hydrochloride

Antihistamines (First Generation)Over-the-Counter (OTC)

Brand Names:

Benadryl, ZzzQuil, Sominex, Unisom SleepGels

Diphenhydramine is a first-generation antihistamine used to relieve allergy symptoms, treat motion sickness, and as a short-term sleep aid.

Overview

Diphenhydramine is a first-generation antihistamine used to relieve allergy symptoms, treat motion sickness, and as a short-term sleep aid.

Uses

Allergic rhinitis, urticaria, itching, common cold symptoms, motion sickness, short-term insomnia.

Dosage

Adults: 25–50 mg every 4–6 hours as needed (max 300 mg/day). As sleep aid: 50 mg at bedtime.

Side Effects

Common: Drowsiness, dry mouth, dizziness, constipation, blurred vision.

Interactions

CNS depressants enhanced sedation. MAO inhibitors increased anticholinergic effects.

Warnings

Causes significant drowsiness. Not recommended for older adults. Avoid alcohol.

Pregnancy

Category B — Generally considered safe for occasional use during pregnancy.

Storage

Store at room temperature.

Frequently Asked Questions

What is Diphenhydramine used for?

Allergic rhinitis, urticaria, itching, common cold symptoms, motion sickness, short-term insomnia.

What are the side effects of Diphenhydramine?

Common: Drowsiness, dry mouth, dizziness, constipation, blurred vision.

Can I take Diphenhydramine during pregnancy?

Category B — Generally considered safe for occasional use during pregnancy.

What are the important warnings for Diphenhydramine?

Causes significant drowsiness. Not recommended for older adults. Avoid alcohol.

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Medical Disclaimer

This drug information is for educational purposes only and should not replace professional medical advice. Drug information is sourced from the FDA National Drug Code Directory and Structured Product Labeling. Always consult with a healthcare provider before starting, stopping, or changing any medication.