diphenhydramine, Benadryl

  • Pharmacy Author:
    Omudhome Ogbru, PharmD

    Dr. Ogbru received his Doctorate in Pharmacy from the University of the Pacific School of Pharmacy in 1995. He completed a Pharmacy Practice Residency at the University of Arizona/University Medical Center in 1996. He was a Professor of Pharmacy Practice and a Regional Clerkship Coordinator for the University of the Pacific School of Pharmacy from 1996-99.

  • Medical and Pharmacy Editor: Jay W. Marks, MD
    Jay W. Marks, MD

    Jay W. Marks, MD

    Jay W. Marks, MD, is a board-certified internist and gastroenterologist. He graduated from Yale University School of Medicine and trained in internal medicine and gastroenterology at UCLA/Cedars-Sinai Medical Center in Los Angeles.

View 10 Common Allergy Triggers

STORAGE: Diphenhydramine should be stored at room temperature, 15 C to 30 C (59 F to 86 F), and the injection should be protected from freezing and light.

DOSING: 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.

DRUG INTERACTIONS:

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).

Medically Reviewed by a Doctor on 3/27/2015

Quick GuideBad Bugs: Identify Bug Bites From Mosquitos, Spiders and More

Bad Bugs: Identify Bug Bites From Mosquitos, Spiders and More
FDA Logo

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

RxList Logo

Need help identifying pills and medications?

Use the pill identifier tool on RxList.

Subscribe to MedicineNet's Allergy and Asthma Newsletter

By clicking Submit, I agree to the MedicineNet's Terms & Conditions & Privacy Policy and understand that I may opt out of MedicineNet's subscriptions at any time.

Health Solutions From Our Sponsors