The first line drug for anaphylaxis is: (PSC - Lumbini 2083)

 # The first line drug for anaphylaxis is: (PSC - Lumbini 2083)

A. Diphenhydramine

B. Epinephrine

C. Hydrocortisone

D. Oxygen

The correct answer is B. Epinephrine.

Intramuscular epinephrine (typically 0.3 to 0.5 mg of a 1:1,000 solution injected into the anterolateral thigh) is the absolute first-line drug of choice. It acts as a physiological antagonist to systemic mediators of anaphylaxis, reversing peripheral vasodilation, reducing tissue edema, and inducing bronchodilation.