Non–IgE-mediated anaphylaxis may be

Non–IgE-mediated anaphylaxis may be immunologicor non-immunologic. The most relevantnon-IgE-mediated immunologic mechanisms mayinvolve the activation of pathways such as the complement system (anaphylatoxins, C3a, andC5a),35 the contact and coagulation systemactivation,36–38 or immunoglobulin G (IgG)-mediated anaphylaxis.39–41 Non-immunologicmechanisms have been described for somedrugs (opioids).42 Ethanol and physical factors,such as exercise, may be involved in triggering anaphylaxis through mechanisms which are notfully elucidated. Mast cells may be activatedthrough receptors such as Mas-related G-proteincoupled receptor member X2 (MRGPRX2) bycertain drugs such as neuromuscular blockingagents and fluoroquinolones