Which of the following is a symptom of anaphylaxis?

• A. Airway swelling
• B. Dizziness
• C. Tachycardia
• D. Rash

Answer: (C)

Anaphylaxis is a systemic reaction where mediators cause widespread vasodilation, increased vascular permeability, and bronchoconstriction. The body often responds with a fast heart rate to maintain perfusion as blood pressure can drop rapidly. Tachycardia is a common, early cardiovascular sign that points to the systemic nature of the reaction and the body's compensatory response. While airway swelling and rash can occur, they’re more variable and depend on the individual’s presentation; dizziness can come from the drop in blood pressure, but the most consistent and readily observable systemic sign among these options is the faster heart rate. So tachycardia best indicates anaphylaxis and should prompt immediate treatment and monitoring.