About diphenhydramine hcl
First-generation antihistamine
Used for
- Relieves allergy symptoms such as sneezing, runny nose, and itching.
- May relieve cough or cold symptoms; evidence for benefit is limited.
- Treats itching from hives or other allergic skin reactions.
Usual adult dose
For allergy symptoms, 25–50 mg every 4–6 hours; maximum 300 mg daily.
Usual dose in children
For ages 2–5, 6.25 mg every 4–6 hours; ages 6–11, 12.5–25 mg every 4–6 hours. Maximum 150 mg daily; not for children under 2 unless directed by a clinician.
Common side effects
- Sleepiness
- Dizziness
- Dry mouth
- Blurred vision
Important warnings
- Can cause marked drowsiness; avoid driving and alcohol.
- Do not combine with other diphenhydramine-containing products or sedatives without medical guidance.
- Avoid for routine cough or cold symptoms in children under 6.
- Overdose can be dangerous, especially for children.
Pregnancy
Use only when needed and after consulting a healthcare professional; available information has not shown a clear increase in birth defects.
Breastfeeding
May cause infant sleepiness or affect milk supply, especially with repeated doses; seek professional guidance.
Interactions
- Alcohol and sedatives can increase drowsiness.
- Monoamine oxidase inhibitors can intensify or prolong effects.
- Other medicines with anticholinergic effects may increase dry mouth, constipation, or blurred vision.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.