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Updated October 06, 2012

Definition: Diphenhydramine is an antihistamine sold over the counter. Diphenhydramine is also sold as a sleep aid.

Considered by most health-care providers to be the gold standard of allergy medications, diphenhydramine provides relief from all types of allergic reactions.

It's even used by emergency medical services to treat or prevent anaphylaxis.

Side Effects

The biggest side effect of diphenhydramine is drowsiness. This side effect is so common that diphenhydramine is also sold as a sleep aid. Generally, buying it as an allergy medication is cheaper than as a sleep aid, so be sure to read the labels.

Side effects of diphenhydramine requiring medical attention:

  • anxiety
  • rapid pulse rate
  • chest pains or palpitations
  • pain during urination
  • dizziness
  • seizures
  • fainting
  • muscle twitching
For more detailed information, see diphenhydramine on Drugs A-Z.
Pronunciation: dye-fen-HYE-dra-meen
Also Known As: Banophen®, Benadryl®
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