What distinguishes anaphylaxis from syncope?

Anaphylaxis is characterized by a severe, systemic allergic reaction that can lead to life-threatening symptoms. One of the hallmark features of anaphylaxis is the presence of respiratory distress, which includes wheezing and bronchoconstriction. This occurs as a result of the body’s immune response to an allergen, leading to swelling and constriction of the airways, making it difficult to breathe. The presence of wheezing is particularly distinctive because it indicates involvement of the respiratory system, which is typically absent in syncope.

On the other hand, syncope, or fainting, generally stems from a temporary reduction in blood flow to the brain, which results in symptoms like light-headedness, blurred vision, and possible loss of consciousness. The symptoms of light-headedness and blurred vision mentioned in another option are more associated with syncope because they suggest inadequate cerebral perfusion.

Thus, the identification of wheezing and bronchoconstriction as indicative of anaphylaxis is what sets this condition apart from syncope, marking it as the correct choice.