Which of the following is a symptom of anaphylaxis, a life-threatening allergic reaction?

Wheezing is a common symptom of anaphylaxis and indicates a narrowing of the airways, which can make breathing difficult. This sound is produced when air flows through constricted bronchial tubes, often due to swelling and inflammation from the severe allergic reaction. Anaphylaxis can lead to respiratory distress, and wheezing serves as a clear sign that immediate medical intervention may be necessary.

In contrast, high blood pressure is generally not a marker of anaphylaxis; the condition often leads to low blood pressure instead due to systemic vasodilation caused by widespread release of histamines. Quiet breathing may suggest a lack of airflow or respiratory distress, which is not typical for anaphylaxis where the affected individual may struggle to breathe and show audible signs. A slow heart rate is also generally not associated with anaphylaxis, where responses typically involve an increased heart rate due to the stress response the body is experiencing.