What is the first-line treatment for anaphylaxis?

• A. Diphenhydramine
• B. Epinephrine
• C. Albuterol
• D. Corticosteroids

Answer: (B)

Anaphylaxis is a life-threatening emergency where airway, breathing, and circulation can deteriorate rapidly. The first-line treatment is epinephrine given by intramuscular injection, typically into the mid-outer thigh. Epinephrine works on multiple receptors to counteract the crisis: alpha-1 constricts blood vessels to raise blood pressure and reduce swelling; beta-1 increases heart output to support circulation; and beta-2 bronchodilates the airways and helps limit release of mediators from mast cells. This single agent quickly reverses the major problems—airway obstruction, bronchospasm, and shock.

Antihistamines like diphenhydramine don’t reverse airway compromise or hypotension promptly and are not sufficient as solo therapy. Albuterol can relieve bronchospasm but doesn’t address the circulating collapse or airway edema. Corticosteroids may help with biphasic or prolonged reactions but act too slowly to treat the acute episode.