What is the recommended first-line intramuscular dose of epinephrine for adult anaphylaxis?

• A. 0.3–0.5 mg of 1:1000 epinephrine IM
• B. 1.0 mg IM
• C. 0.1 mg IM
• D. 2 mg IM

Answer: (A)

Prompt epinephrine is the cornerstone of treating adult anaphylaxis because it provides rapid reversal of airway edema and bronchospasm while supporting blood pressure through both alpha- and beta-adrenergic effects. The best first-line intramuscular dose is 0.3–0.5 mg of a 1:1000 epinephrine solution, given into the mid-anterolateral thigh. This amount delivers sufficient drug quickly with a favorable safety profile, and if symptoms persist or recur, the dose can be repeated every 5–15 minutes. Doses outside this range, such as 0.1 mg (too low) or 1.0–2 mg (excessively high for initial IM use), are not appropriate for first-line management.