Coughing is an action the body takes to get rid of substances that are irritating the air passages. A cough is usually initiated to clear a buildup of phlegm in the trachea. Coughing can also be triggered by a bolus of food entering the trachea rather than the esophagus due to a failure of the epiglottis. Frequent or chronic coughing usually indicates the presence of a disease. Provided the patient is a non-smoker and has a normal chest X-ray, the cause of chronic cough in 93% of all patients is due to asthma, heartburn or post-nasal drip. Other causes of chronic cough include chronic bronchitis and medications such as ACE inhibitors. Coughing can happen voluntarily as well as involuntarily.
