What is the hallmark symptom of asthma?

Wheezing is considered the hallmark symptom of asthma because it specifically indicates the presence of airway obstruction and inflammation, which are characteristic of this condition. Wheezing occurs due to the narrowing of the air passages, which causes a high-pitched whistling sound during exhalation. This phenomenon is most commonly associated with asthma and is a direct result of bronchoconstriction, increased mucus production, and airway inflammation during an asthma attack.

While coughing, chest tightness, and shortness of breath are also common symptoms of asthma, they are not as distinctively associated with the condition as wheezing. Coughing can occur in various respiratory issues, chest tightness might not always indicate asthma specifically, and shortness of breath can be attributed to numerous other health conditions. Therefore, the specificity of wheezing makes it a defining symptom in the diagnosis and management of asthma.