Which statement is true about treating anaphylaxis?

• A. Epinephrine
• B. Diphenhydramine
• C. Oxygen
• D. Nitroglycerin

Answer: (A)

When treating anaphylaxis, the immediate, most effective step is administering epinephrine. It rapidly reverses the life-threatening features by acting on multiple targets: alpha-1 receptors tighten blood vessels to raise blood pressure and reduce airway swelling; beta-1 receptors boost heart output to improve perfusion; and beta-2 receptors dilate the airways and help limit further release of allergic mediators from mast cells. This combination often stops airway obstruction, improves breathing, and stabilizes circulation, which is why epinephrine is the first-line treatment.

Diphenhydramine can help with itching and hives but it does not reverse airway swelling or shock and therefore cannot substitute for epinephrine. Oxygen supports breathing if hypoxia is present, but it doesn’t treat the underlying reaction. Nitroglycerin is not appropriate for anaphylaxis and can worsen low blood pressure.