Which symptom differentiates anaphylaxis from syncope?

In cases of anaphylaxis, one key symptom that stands out is the presence of wheezing and trouble breathing. Anaphylaxis is a severe, potentially life-threatening allergic reaction characterized by respiratory distress, which can manifest as wheezing due to bronchoconstriction and airway swelling. This respiratory involvement is a crucial indicator that helps distinguish anaphylaxis from syncope, which is typically characterized by a temporary loss of consciousness due to a lack of blood flow to the brain, often associated with changes in posture or stress.

While loss of consciousness can occur in both scenarios, in anaphylaxis, it is usually accompanied by other symptoms such as difficulty breathing, swelling, hives, and gastrointestinal symptoms. Abdominal pain can also be present in anaphylactic reactions but is not unique to it, as it can occur in various conditions. A severe headache does not typically align with the expected symptoms of anaphylaxis, further noting that respiratory symptoms are distinctive to allergic reactions. Thus, wheezing and trouble breathing serve as critical indicators to identify and differentiate anaphylaxis effectively from syncope.