Cough is an important protective mechanism for the maintenance of airways and lungs. Cough receptors are located in the larynx and near the tracheobronchial tree. They are mediated by rapidly-adapting (i.e., irritant) Adelta fibers, even though the other receptors such as C-fiber receptors might be contributing.

Cough plasticity along with the interactions of cough pathways might occur centrally to improve the cough reflex. The occurrence of an increased cough reflex when measured by a tussive response to capsaicin or citric acid in chronic cough patients specify that there is sensitisation of the cough reflex.

The most common cause of acute cough is mostly after a common cold that lasts mostly for less than 2 weeks. Cough persisting longer might be due to asthma and its different forms such as cough variant asthma and eosinophilic bronchitis, rhinosinusitis (mostly postnasal drip), gastro-esophageal reflux, chronic bronchitis, bronchiectasis and angiotensin-converting enzyme inhibitor therapy.

Chronic persistent cough might contribute to a significant deterioration of quality-of-life events. Bronchial tumors should be excluded by a chest radiograph. The management and treatment of chronic cough comprises investigation and treatment of the associated causes. This can sometimes lead to control of cough. With proportion to patients, cough might be idiopathic and can remain uncontrolled. Currently-available antitussives such as dextromethorphan are modestly effective in controlling the cough.

Source: Chung KF. Pathophysiology and therapy of chronic cough. Minerva Med. 2005 Feb; 96(1):29-40.