Exercise-induced allergies: the role of histamine release.

Exercise is a physical cause of allergic reactions, including exercise-induced anaphylaxis (EIAna), exercise-induced urticaria (EIU), exercise-induced asthma (EIA), and exercise-induced rhinitis (EIR). Since its first description in 1979, EIAna has been reported with variable clinical manifestations, with exercise alone, and in combination with food ingestion. Elevated serum histamine levels and cutaneous mast cell degranulation have been noted. Exercise-induced urticaria appears as small, punctate lesions that differ from the classic coalescent type seen with EIAna. Variant forms of EIAna with cholinergic urticarial lesions manifesting systemic collapse and/or respiratory distress have been studied. Exercise-induced urticaria and cold-induced urticaria may cause elevated plasma histamine levels coincident with the onset of pruritus and hives. Theories accounting for EIA include respiratory heat loss, water loss, and mast cell activation. Although some studies have shown increased plasma histamine with EIA, others have not. Recently, bronchoalveolar lavage in atopic subjects with EIA has been evaluated preexercise and postexercise, with no significant differences in histamine or tryptase, suggesting a pathogenesis of EIA independent of the mast cell. Exercise-induced rhinitis, with varying degrees of rhinorrhea, congestion, and sneezing, has been increasingly recognized in athletes who run, cycle, and ski. Cold-air-induced rhinorrhea in laboratory challenges displays a mediator release pattern similar to that produced by allergen-induced nasal challenges. Therapeutically, H1 antihistamines are recommended for EIAna both as pretreatment and acute therapy. H1 antihistamines may be helpful in EIU, but are recommended for EIAna both as pretreatment and acute therapy.(ABSTRACT TRUNCATED AT 250 WORDS)