Anaphylaxis

Anaphylaxis can progress from apparently mild allergic symptoms to airway obstruction or circulatory collapse within minutes. The diagnosis is made from the timing and pattern of findings; do not wait for a rash, hypotension, or a laboratory result. Give IM epinephrine immediately when anaphylaxis is suspected: 0.01 mg/kg of 1 mg/mL (1:1000) solution into the anterolateral thigh, to a maximum single dose of 0.5 mg. Activate EMS without delaying the injection. Place the patient supine with the legs elevated if tolerated; use a position of comfort for severe breathing difficulty or vomiting, and do not allow the patient to stand or walk. A pregnant patient should be positioned with left uterine displacement or in the left lateral position while maintaining airway and circulation. The practical priority is simple: treat the evolving syndrome first, then refine the trigger and longer-term plan after the airway, breathing, and circulation are stable.