Treatment of persistent dry cough: if possible, treat the cause; if not, treat the cough.

Persistent dry cough is a common presenting symptom which may be associated with considerable morbidity. In the majority of patients, systematic investigation reveals an underlying cause, usually asthma, postnasal drip, gastrooesophageal reflux or various combinations of these conditions. Intensive treatment of the underlying cause usually leads to improvement or resolution of the cough. However, in a minority of patients, no underlying cause is identified despite appropriate investigation. In these patients with idiopathic persistent dry cough, cough sensitivity to inhaled tussigens is enhanced, suggesting that increased sensitivity of airway sensory nerves is important in pathogenesis. An ideal antitussive would reduce this increased sensitivity to normal levels without significant adverse effects but currently available antitussives fall short of this expectation. This review discusses the currently available antitussive therapy and explores potential avenues for the development of future novel antitussive therapies.