How much and how often should you use diphenhydramine?
Your dose and how often you take diphenhydramine will depend on the following factors:
- Age
- Your health
- Health of your liver
- Health of your kidneys
- Medicines recommended by your doctor
- Any other medicines being used
- Herbal supplements in use
- Response to the medicine
Adult
- Recommended: 5 -10 mg once daily
- Maximum: 10 mg/day
Children (children of 6 years and above)
- Recommended: 5 – 10 mg once daily
- Maximum: 10 mg/day
Mechanism of Action
Diphenhydramine works by producing an antihistamine action which competitively blocks H1 receptors. It then binds to the H1 receptors present in the smooth muscles of the gastrointestinal tract, bronchi, large blood vessels and uterus. Once there, it is able to inhibit histamine-induced allergic symptoms. It does not, however, inhibit the release of histamine itself.