Evaluation of the patient with chronic cough.

Patients with chronic cough should avoid exposure to irritants that can trigger cough, and those who smoke should stop smoking. Patients who develop chronic cough in association with angiotensin-converting enzyme inhibitor therapy should be switched to an agent from another drug class. If cough persists, a chest radiograph should be ordered to rule out malignancy and other serious conditions. Postnasal drip syndrome, asthma, and gastroesophageal reflux disease are the most likely causes of chronic cough in adults. If postnasal drip syndrome is suspected, a trial of a decongestant and a first-generation antihistamine is warranted. Pulmonary function testing with a methacholine challenge is the preferred test for confirming the diagnosis of asthma. Gastroesophageal reflux disease usually is diagnosed based on the symptoms and after a trial of therapy. If the cause of chronic cough remains unclear, high-resolution computed tomographic scanning of the chest, bronchoscopy, and referral to a pulmonary specialist may be indicated. The approach to diagnosing chronic cough in immunocompromised patients and children is similar to the approach in immunocompetent adults. However, a CD4+ cell count can help determine the potential for opportunistic infections in immunocompromised patients. Respiratory tract infections, asthma, and gastroesophageal reflux disease are the most common causes of chronic cough in children. Foreign body aspiration should be considered in young children. Congenital conditions, cystic fibrosis, and immune disorders are possible diagnoses in children with chronic cough and recurrent infection.