Background     Pathophysiology Severe type 1 hypersensitivity reaction i.e. IgE-mediated mast cell activation. Vasodilation leads to distributive shock and capillary leak leads to angio-oedema. Causes Food (50%): peanuts and tree nuts, eggs, fish and shellfish, strawberries. Drugs: penicillin, NSAIDs, opioids, anaesthetic agents (especially muscle relaxants), contrast. Bee or wasp stings. Latex Nonallergic anaphylaxis Non-IgE mediated mast cell activation. Aka nonimmunologic anaphylaxis. Formerly known as anaphylactoid reaction. Similar presentation and management to allergic anaphylaxis. Causes: contrast, vancomycin, opioids, anaesthetic agents. Epidemiology 1/1000 lifetime risk. 1/10,000 annual incidence. 20 UK deaths annually. Signs and symptoms Airway, breathing, or circulation problems: Circulation: ↓BP and ↑HR, loss of consciousness. Airway: SOB, cyanosis, stridor due to laryngeal oedema, wheezing due to bronchospasm. Other...