The common causes of cough include,
1)Acute respiratory Infection : Pneumonia,Bronchitis
2)Chronic Respiratory Infection : TB(Pulmonary Tuberculosis), Postnasal drip.
3)Airway disease : Asthma , COPD (Chronic Obstructive Pulmonary Disease).
4)Irritants : Cigarettes Smoking, Inhaled Foreign Bodies.
5)Drug Induced : Inhaled drugs(aerosols), ACE - Inhibitors (Anti-Hypertensive)