A chronic cough (ie, a cough lasting more than 8 weeks 1) has many possible causes. Physicians should use a structured diagnostic approach based on observing the clinical picture, trying therapy for the likely cause, obtaining targeted investigations, and referring to a specialist when needed (FIGURE 1). To begin, obtain a clinical history, perform a physical examination, and order a chest radiograph. In the history, look for exposure to environmental irritants such as tobacco smoke, allergens, or dust, or medications such as angiotensin-converting enzyme (ACE) inhibitors or oxymetazoline (Afrin). If a potential irritant is present, it should be avoided or stopped immediately. 1-3 If the cough improves partially or fully when exposure to the irritant is stopped, this supports a diagnosis of chronic bronchitis or, in the case of ACE inhibitors, ACE-inhibitor-induced cough. The character of the cough (eg, paroxysmal, loose, dry, or productive 1) has not been shown to be diagnostically useful or specific. If the chest radiograph is abnormal, then the diagnostic inquiry should be guided by the abnormality. Abnormalities that cause cough include bronchogenic carcinoma, sarcoidosis, and bronchiectasis. If the radiograph is normal, then upper airway cough syndrome, asthma, gastroesophageal reflux disease (GERD), chronic bronchitis, or nonasthmatic eosinophilic bronchitis is more likely.
