Life-threatening inhalant allergy: typical anaphylaxis induced by inhalational allergen challenge in patients with idiopathic recurrent anaphylaxis.

Eight patients, referred to an allergy service because of anaphylactic syndromes, were investigated for the usual causes (drugs, foods, insect stings etc.) without satisfactory results. All were atopic by history and/or allergy skin testing. Inhalation challenges, using nebulized common inhalant allergens to which the patients were positive by skin tests, were performed to test whether such inhaled allergens could be causing the anaphylactic episodes. Four of the eight patients developed anaphylactic episodes similar to the spontaneous attacks. Two of the other four patients developed precipitous asthma with some suggestion of non-pulmonary anaphylactic features. It is suggested that inhaled allergens may be a common cause of recurrent anaphylaxis where other recognized causes have been excluded.