Which symptom differentiates anaphylaxis from syncope?

The symptom that differentiates anaphylaxis from syncope is wheezing and bronchoconstriction. Anaphylaxis is a severe allergic reaction that can cause a variety of symptoms, including respiratory distress characterized by wheezing, difficulty breathing, and bronchoconstriction. These respiratory symptoms indicate that the airway is compromised due to an allergic response, which is critical in identifying anaphylaxis.

Syncope, on the other hand, is a temporary loss of consciousness typically due to decreased blood flow to the brain, often caused by factors such as vasodilation, dehydration, or heart problems. In syncope, patients do not experience respiratory symptoms like wheezing or bronchoconstriction. Therefore, the presence of wheezing distinguishes anaphylaxis from syncope, highlighting a respiratory system involvement that is not accounted for in syncope.

Other symptoms listed, such as loss of consciousness, pallor, or seizures, may overlap in various conditions, but they do not specifically indicate respiratory compromise, which is pivotal in diagnosing anaphylaxis.