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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 the dosage for diphenhydramine?
Diphenhydramine doses vary depending on formulation, and has its maximal effect about one hour after it is taken.
- When used to treat insomnia, it is prescribed at bedtime. Indivduals over the age of 60 years are especially sensitive to the sedating and anticholinergic effects of diphenhydramine, and the dose should be reduced.
- A common regimen for treating adult allergic reaction is 25-50 mg every 4-6 hours not to exceed 300 mg daily.
- Insomnia is treated with 50 mg taken 30 minutes before bedtime.
Which drugs or supplements interact with diphenhydramine?
Diphenhydramine adds to (exaggerates) the sedating effects of alcohol and other drugs than can cause sedation such as the benzodiazepine class of anti-anxiety (for example, diazepam [Valium], lorazepam [Ativan], clonazepam [Klonopin], alprazolam [Xanax]), the narcotic class of pain medications and its derivatives (for example, oxycodone and acetaminophen [Percocet], and hydrocodone and acetaminophen [Vicodin], guaifenesin with hydromorphone [Dilaudid], codeine, propoxyphene [Darvon]), the tricyclic class of antidepressants (for example, amitriptyline [Elavil, Endep], imipramine [Tofranil], desipramine [Norpramin]), and certain antihypertensive medications (for example, clonidine [Catapres], propranolol [Inderal]). Diphenhydramine also can intensify the drying effects of other medications with anticholinergic properties (for example, dicyclomine [Bentyl] and bethanechol [Urecholine], probanthine).
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