Which medications in the drug class H2 antagonists (antihistamines) are used in the treatment of Acute Urticaria?

Updated: Mar 21, 2018
  • Author: Henry K Wong, MD, PhD; Chief Editor: Michael A Kaliner, MD  more...
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Answer

H2 antagonists (antihistamines)

These are reversible, competitive blockers of histamine at H2 receptors, particularly those in gastric parietal cells. The H2 antagonists are highly selective, do not affect H1 receptors, and are not anticholinergic agents. They block the vasodilation mediated by the H2 receptors in blood vessels, possibly leading to less edema formation in urticaria.

When used as single agents for urticaria, they are not effective. However, the combination of an H1 antagonist with an H2 antagonist is more effective than an H1 antagonist alone. [52, 53] Any of the H2 blockers can be used. Two of the most commonly used agents are ranitidine and cimetidine.

Famotidine (Pepcid)

Famotidine is an H2 antagonist that, when combined with an H1 type, may be useful in treating allergic reactions that do not respond to H1 antagonists alone.

Cimetidine (Tagamet)

Cimetidine is an H2 antagonist that, when combined with an H1 antagonist, may be useful in treating itching and flushing in urticaria and contact dermatitis that do not respond to H1 antagonists alone. Use in addition to H1 antihistamines.

Ranitidine (Zantac)

Ranitidine is an H2 antagonist that, when combined with an H1 type, may be useful in treating urticaria when urticaria is not responsive to H1 antagonists alone.


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