Cough is a common symptom in people who have asthma, although it can happen for many other reasons. It's generally a healthy reflex that helps clear the airways (the tubes that carry air into and out of the lungs) in the throat and ches. But coughing is often also a sign of airway irritation, as is the case in a person with asthma. For many children with asthma, a cough is the main — and sometimes even only — symptom. But some people with asthma may only cough at night or while exercising.