What is the role of H2 antihistamines in the treatment of urticaria (hives)?

Updated: Sep 16, 2020
  • Author: Henry K Wong, MD, PhD; Chief Editor: Dirk M Elston, MD  more...
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Answer

H2 antihistamines, such as cimetidine, famotidine, and ranitidine, may have a role when used in combination with H1 antihistamines in urticaria. H1 and H2 antihistamines are thought to have a synergistic effect that may result in a more rapid and complete resolution of urticaria than H1 antihistamines alone. [45] Cimetidine, in particular, is thought to effect cytochrome P450 enzymes involved in the metabolism of first-generation antihistamines, thus increasing their plasma concentrations. [32] Because of this, H2 antihistamines are often added in combination with H1 antihistamines in the treatment of acute and chronic urticaria. However, the evidence supporting the use of H2 antihistamines in combination with H1 antihistamines is weak and does not seem to show any advantage over use of H1 antihistamines alone. Thus, their addition is often physician dependent. [36, 32, 43, 46]


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