The role of H2 antagonists in perennial allergic rhinitis.

The biological effects of anti-H2 in allergic reactions are dose dependent: low doses enhance, and high doses significantly decrease the reaction of hypersensitivity. The administration of cimetidine H2 antagonist to 20 perennial allergic rhinitis patients brought about an abatement in the symptoms and a decrease in the total serum immunoglobulin E (IgE) levels in 72% of treated patients, but no variation was perceived in placebo-treated patients. These results strengthen the hypothesis of anti-H2-induced immunoregulatory effects and suggest a possible way of inhibiting IgE synthesis in vivo.