Recurrent idiopathic anaphylaxis.

Eighteen patients with recurrent episodes of life-threatening anaphylaxis of unknown cause were studied. Each patient had repeated detailed histories taken and had repeated physical examinations, hypersensitivity skin tests to foods, and complete blood cell counts. In addition, each patient underwent stringent dietary manipulation. Seventeen of the 18 patients underwent a series of studies. Three patients were hospitalized for study. Results of all tests were essentially normal except for an elevated plasma histamine level during attacks in two patients. Episodes could not be prevented with antihistamine therapy. Attacks were treated successfully by instructing the patients in the self-administration of epinephrine. It thus appears that recurrent episodes of anaphylaxis due to nonimmunologic histamine release of anaphylaxis due to nonimmunologic histamine release can occur without discernible cause and can be lifethreatening.