Anaphylaxis is MOST accurately defined as which of the following?

• A. A severe allergic reaction that typically resolves without treatment.
• B. A moderate allergic reaction that primarily affects the vasculature.
• C. An allergic reaction that causes bronchodilation and vasoconstriction.
• D. An extreme allergic reaction that may affect multiple body systems

Answer: (D)

Anaphylaxis is a severe, systemic allergic reaction that can involve multiple body systems and progress rapidly toward life-threatening consequences. It happens when mediators released from mast cells and basophils after allergen exposure trigger widespread vasodilation and increased vascular permeability (leading to a dangerous drop in blood pressure), along with airway involvement such as bronchoconstriction and airway edema. Because of this systemic involvement, the description that best fits is an extreme allergic reaction that may affect multiple body systems.

That’s why statements suggesting it resolves on its own are not correct, or that it’s a moderate reaction confined mainly to the vasculature don’t fit, or that it causes bronchodilation and vasoconstriction are inaccurate. In anaphylaxis, you see bronchoconstriction and vasodilation with multi-system effects rather than the opposite.