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- What is diphenhydramine, and how does it work (mechanism of action)?
- What brand names are available for diphenhydramine?
- Is diphenhydramine available as a generic drug?
- Do I need a prescription for diphenhydramine?
- What are the side effects of diphenhydramine?
- What is the dosage for diphenhydramine?
- Which drugs or supplements interact with diphenhydramine?
- Is diphenhydramine safe to take if I'm pregnant or breastfeeding?
- What else should I know about diphenhydramine?
What is diphenhydramine, and how does it work (mechanism of action)?
Diphenhydramine is an antihistamine used for treating allergic reactions. Histamine is released by the body during several types of allergic reactions and--to a lesser extent--during some viral infections, such as the common cold. When histamine binds to receptors on cells, it stimulates changes within the cells that lead to the release of chemicals that cause sneezing, itching, and increased mucus production. Antihistamines compete with histamine for cell receptors and bind to the receptors without stimulating the cells. In addition, they prevent histamine from binding and stimulating the cells. Diphenhydramine also blocks the action of acetylcholine (anticholinergic effect) and is used as a sedative because it causes drowsiness. The FDA originally approved diphenhydramine in 1946.
What brand names are available for diphenhydramine?
Benadryl, Sominex, Unisom, Nytol, and several others
Is diphenhydramine available as a generic drug?
GENERIC AVAILABLE: Yes
Do I need a prescription for diphenhydramine?
: No. Yes (Injection)
What are the side effects of diphenhydramine?
Diphenhydramine commonly can cause:
- disturbed coordination,
- drying and thickening of oral and other respiratory secretions, and
- urinary retention.
Diphenhydramine also may cause
- low blood pressure,
- increased heart rate,
- blurred vision,
- double vision,
- loss or appetite, or
Diphenhydramine should be used with caution (if at all) in persons with narrow-angle glaucoma, prostatic hypertrophy (enlarged prostate gland), hyperthyroidism, cardiovascular disease, high blood pressure (hypertension), and asthma.
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