Health Tip: What Causes a Chronic Cough

(HealthDay News) -- Coughing serves an important purpose -- to help you expel mucus, microbes and other foreign particles from your respiratory tract.

This helps protect the lungs from infection and inflammation, Harvard Medical School says. A cough becomes chronic if it lingers for at least three to eight weeks, the school adds.

Its list of reasons for a chronic cough includes: