H2-antagonist in IgE-mediated type I hypersensitivity reactions: what literature says so far?

Histamine is a monoamine synthesized from the amino acid histidine that is well-known for its role in IgE-mediated anaphylaxis but has shown pleiotropic effects on the immune system, especially in order to promote inflammatory responses. H(1)-receptor antagonist are common drugs used in mild/moderate allergic reactions whereas H(2)-receptor antagonist are commonly administered in gastric ulcer but showed some properties in allergy too. The EAACI guidelines for diagnosis and treatment of anaphylactic reactions recommend their use as third-line therapy in adjunct to H(1)-antagonists. The purpose of this article is to produce a complete summary of findings and evidence known so far about the usefulness of H(2)-receptor antagonist in allergic reactons.