Which medications in the drug class Antihistamines are used in the treatment of Anaphylaxis?

Updated: May 16, 2018
  • Author: S Shahzad Mustafa, MD; Chief Editor: Michael A Kaliner, MD  more...
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Antihistamines are primarily effective against cutaneous effects of anaphylaxis. Also may help antagonize cardiac and respiratory effects; should be used routinely in most cases of anaphylaxis. IV administration is preferable when a rapid effect is desired. IM dosing also is effective but has a slower onset than IV and may cause local tissue irritation. PO doses must be larger than parenteral doses because of 50% first-pass metabolism in the liver.

Most recommendations for use of antihistamines state that they should be continued for 2-3 days after treatment of the acute anaphylactic event.

Diphenhydramine (Benadryl)

Diphenhydramine has a long history of efficacy and relative safety. It has an FDA indication for anaphylaxis. IV administration provides faster onset of action.

Hydroxyzine (Vistaril)

Hydroxyzine is an H1 antihistamine. It may suppress histamine activity in the subcortical region of the CNS.

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