[Chronic cough].

Cough is a powerful physiological reflex mechanism that causes central airways to be cleared of foreign material and excess secretions. Chronic cough is a very common presenting symptom in general practice with a prevalence in the population of about 5%. As a general rule, persistent cough represents organic disease of the upper and lower airways, the lung parenchyma, the pulmonary circulation, the pleural space, the mediastinum and the upper gastro-intestinal tract. The most common cause is cigarette smoking, but virtually any chronic lung disease may be occasionally associated with cough. Complications of coughing are tussive syncopes, rib fractures, rupture of respiratory muscles and eventually hernias. Based on a detailed clinical history and physical examination, the investigation includes a chest radiograph, spirometry, and sputum smears. Radiography of the sinuses, bronchoscopy and upper gastro-intestinal endoscopy may be added. If the treatment of an underlying disease is successful, chronic cough may disappear. There are few 'antitussive' drugs with proven suppression of the cough reflex.