Which condition is characterized by a hissing or wheezing sound during breathing?

Asthma is characterized by a hissing or wheezing sound during breathing due to the narrowing of the airways. This narrowing can result from inflammation, bronchoconstriction, or increased mucus production, all of which are common in asthma. The wheezing sound occurs specifically during expiration, although it can also be present during inspiration in more severe cases. This condition is often triggered by allergens, respiratory infections, exercise, or environmental factors, leading to the characteristic sounds as air struggles to pass through the constricted airways.

While other conditions such as COPD can also produce wheezing, asthma is specifically known for this symptom, especially in children and individuals with a history of allergic reactions. Heart murmurs relate to abnormal blood flow in the heart and do not cause wheezing, while pneumonia can present with other lung sounds and symptoms but is typically associated with crackles rather than wheezing. Thus, the defining symptom of a hissing or wheezing sound highlights asthma as the correct condition.