First-line treatment for anaphylaxis?

• A. Diphenhydramine IM
• B. Epinephrine intramuscularly 0.3-0.5 mg
• C. Albuterol inhalation
• D. Corticosteroids IV

Answer: (B)

The most important step in managing anaphylaxis is to reverse the life-threatening airway, breathing, and circulation problems as quickly as possible, and the medication that does this best is epinephrine given right away. When given intramuscularly in the mid-outer thigh, epinephrine acts on multiple receptors to rapidly reduce airway edema and bronchospasm while constricting blood vessels to raise blood pressure. This single intervention addresses the key dangerous features of anaphylaxis, making it the first-line treatment. The standard adult dose is 0.3–0.5 mg, and you can repeat it every 5–15 minutes if symptoms persist or recur, under medical supervision.

After administering epinephrine, supportive steps are essential: secure the airway, provide high-flow oxygen, establish IV access, and monitor vitals. Diphenhydramine and corticosteroids are helpful as adjuncts for symptoms like hives or to reduce late-onset reactions, but they do not treat the immediate life-threatening aspects and therefore are not first-line. Albuterol may assist with bronchospasm but does not reverse the underlying anaphylaxis, so it’s used as a secondary measure if wheezing persists after epinephrine. In summary, epinephrine is the best initial treatment because it rapidly counteracts the critical pathophysiology of anaphylaxis.