Management of persistent dry cough

Cough is probably the commonest symptom affecting humans, with prevalence rates variously reported within the range 5–40%.1 Acute or short lived cough, which most commonly occurs in association with viral upper respiratory infection, is of little consequence, usually resolving in a matter of days. Persistent cough, however, may be associated with considerable morbidity including sleep loss, exhaustion, irritability, urinary stress incontinence, cough syncope, impaired performance in daily activities, and considerable social disability. Rib fractures, pneumothorax, pneumomediastinum, and subcutaneous emphysema have been reported in severe cases.2 Persistent productive cough is usually due to cigarette smoking, chronic bronchitis or bronchiectasis, and diagnosis is usually straightforward. Persistent dry cough poses a greater diagnostic and therapeutic challenge.

When clinical evaluation and basic investigations such as spirometry and chest radiography are normal, the cause of persistent dry cough may be elusive and such patients pose considerable difficulty in the clinic. Thorough systematic investigation is both necessary and worthwhile, necessary because the patient may present with cough alone without any typical features of the underlying cause, and worthwhile because treatment of the cause usually leads to resolution of the cough.3 4 Several studies have shown that the only underlying diagnoses …