What is the most appropriate initial treatment for anaphylaxis in a peanut-allergic child?

• A. Epinephrine autoinjector
• B. Oxygen by NRB
• C. Diphenhydramine
• D. IV fluids

Answer: (A)

Anaphylaxis is a rapid, life-threatening reaction where airway swelling, bronchospasm, and shock can develop quickly after exposure to a trigger like peanuts. The most important first step is giving epinephrine right away via an autoinjector. Epinephrine acts on multiple receptors to rapidly reverse airway edema and bronchoconstriction (through beta-2 effects) and to support blood pressure (through alpha-1 effects and beta-1 support). This single intervention directly addresses the life-threatening processes driving the reaction and can prevent progression to airway collapse and circulatory collapse.

Oxygen helps with breathing if there’s distress or hypoxia, but it doesn’t stop the underlying reaction. Diphenhydramine may help with some skin symptoms but does not prevent or reverse airway compromise or shock. IV fluids are important if there’s hypotension, but they’re not the initial treatment to halt the reaction and should follow epinephrine administration.