A severe, rapid-onset systemic hypersensitivity reaction.
Key points
• Airway, breathing or circulation compromise with skin changes soon after an allergen.
• Give intramuscular adrenaline promptly into the anterolateral thigh — 0.5 mg (1:1000) for adults and age- and weight-appropriate dosing for children; repeat after 5 minutes if there is no improvement.
• High-flow oxygen, IV fluids and lie the patient flat; antihistamine and steroid are secondary.
• Observe for a biphasic reaction; prescribe an adrenaline auto-injector and refer to allergy.
Memory trick
Anaphylaxis = IM adrenaline first, into the thigh.