Cough is an essential defensive reflex that aids in clearance of secretions and particulate matter from the airways and ensures protection from aspiration of foreign materials that might occur subsequent to aspiration or inhalation of particulates, pathogens, accumulated secretions, postnasal drip, inflammation and its associated mediators. Under usual conditions, cough serves a vital protective role in the airways and lungs, but it is also one of the most common symptoms that lead patients to consult a primary care practitioner.1,2 Currently, cough is a growing medical, economic and social problem. The incidence of this symptom in adult population ranges from 5 to 40%, depending on environmental characteristics, seasonal variations and habit of smoking.
Based on the duration of symptoms, cough can be classified into acute, sub-acute and chronic cough. Acute cough is the one that resolves usually within 3 weeks, while sub-acute lasts for 4-7 weeks. Chronic cough is defined as an episode of cough that persists for more than 8 weeks. Finding the etiology for chronic cough is a diagnostic challenge for most of the primary care physicians.4 In spite of adherence to an established protocol in the diagnosis and management of chronic cough, majority of patients find insignificant improvements in symptoms.