Which key sign is associated with anaphylaxis?

The key sign associated with anaphylaxis is a significant drop in blood pressure. Anaphylaxis is a severe, life-threatening allergic reaction that can occur rapidly. It typically involves the release of histamine and other chemicals into the bloodstream, leading to vasodilation and increased vascular permeability. This causes blood vessels to dilate and eventually results in a dramatic drop in blood pressure, which can lead to shock if not treated promptly.

While the other signs like rash, swelling in the throat, and wheezing are also important indicators of anaphylaxis, the drop in blood pressure is critical as it directly affects the circulatory system and indicates the severity of the reaction. Recognizing hypotension as a sign of anaphylaxis is essential for timely intervention and treatment, such as the administration of epinephrine, to stabilize the patient's condition.