What is the primary mechanism of action of epinephrine in anaphylaxis?

• A. Inhibition of histamine release only
• B. Decreased heart rate and vasodilation
• C. Vasoconstriction to raise blood pressure and reduce edema, plus bronchodilation
• D. Direct receptor blockade of leukotrienes

Answer: (C)

The main action of epinephrine in anaphylaxis is to counter the sudden, widespread mediator effects by acting on multiple receptors to stabilize the patient quickly. Alpha-1–driven vasoconstriction raises blood pressure and reduces mucosal edema, helping to prevent airway swelling and shock. At the same time, beta-2–mediated bronchodilation relieves bronchospasm, easing breathing. The heart also benefits from beta-1 effects, improving perfusion. This combination directly targets the key problems in anaphylaxis: low blood pressure, airway obstruction, and swelling. It’s not about solely inhibiting histamine release, not about decreasing heart rate or causing vasodilation, and it doesn’t block leukotrienes directly.