What is a cough?
A cough is a sudden blast of air from the lungs. Coughing is a reflex that clears the air passages, in order to keep them open. The cough reflex is an important defense mechanism: coughing expels bacteria, mucus and foreign substances that can cause pneumonia. Any process that irritates the windpipe or air passageways in the lungs can cause a cough. Common causes include chronic bronchitis, COPD, asthma, and upper respiratory infections.

What are the symptoms of a cough?
A cough may be dry or produce mucus. The mucus may be think and white or thick and colored brown or yellow. In some cases, a cough may produce blood-streaked mucus. Commonly associated symptoms are fever, chest wall pain, wheezing, sinus congestion, and breathing difficulty.

How does the doctor treat a cough?
Treatment for cough depends on underlying cause. Treatment for a cough may include avoidance of smoking, inhaled bronchodilators, cough suppressants, antihistamines, corticosteroids, and antibiotics.