Chronic cough.

Chronic cough is defined as a cough that lasts for more than three weeks. More than 90 percent of cases of chronic cough result from five common causes: smoking, post-nasal drip, asthma, gastroesophageal reflux and chronic bronchitis. Although in most patients chronic cough has a single cause, in up to one fourth of patients, multiple disorders contribute to the cough. A stepwise evaluation in patients with chronic cough can minimize the invasiveness and expense of the work-up. Initial screening of patients with chronic cough should search for smoking, occupational exposure to an airway irritant, cough-inducing medications, airway hyperresponsiveness following upper respiratory infection, chronic bronchitis or any systemic symptoms suspicious for serious disease. Patients who are not diagnosed after an initial screening are evaluated or empirically treated in a stepwise fashion for postnasal drip, asthma and reflux. Bronchoscopy is reserved for use in the few patients still without a diagnosis after the previous steps have been completed.