What is the first-line treatment for anaphylaxis in adults?

• A. Administer 0.3 mg adrenaline IM
• B. Administer 0.5 mg adrenaline IM in adults, repeat every 5 minutes if needed
• C. Administer antihistamines only
• D. Place patient in lateral position and monitor

Answer: (B)

Adrenaline given promptly is the frontline treatment because it quickly reverses the main life-threatening features of a severe allergic reaction. It works on several fronts: constricting blood vessels to raise blood pressure and reduce swelling in the airways, increasing heart output to improve circulation, and relaxing the bronchi to relieve wheeze and airway obstruction. It also helps stabilize the reaction by limiting further mediator release from mast cells.

The recommended approach in adults is an intramuscular injection into the thigh as soon as anaphylaxis is suspected, with additional doses given at short intervals if symptoms persist or recur. This rapid, repeatable dosing is what makes adrenaline the best initial therapy, since antihistamines and steroids do not reverse airway compromise or hypotension quickly enough and are only adjuncts. Providing supportive care—like keeping the patient comfortable and monitoring vitals—is important, but it does not replace adrenaline as the first-time action needed to treat anaphylaxis.