IGHE and anaphylaxis: The mechanisms underlying drug-induced anaphylaxis include both allergic and nonallergic reactions, with the former being IgE-mediated or non-IgE-mediated and the latter including directional release of mediators by mast cells and basophils, activation of the contact system, disturbances of arachidonic acid metabolism, and recruitment of complement factors, coagulation factors, and fibrinolytic factors.