Chronic cough is a cough that lasts beyond two months. It indicates presence of an underlying disease that needs to be diagnosed and treated appropriately.
The most common causes of persistent cough are post nasal drip (due to allergic rhinitis, sinusitis, nasal polyps or other conditions), asthma, non-asthmatic eosinophilic bronchitis, allergies, acid reflux(GERD), some high blood pressure medication (ACE inhibitors),smoking, bronchiectasis, post infection cough, emphysema and chronic bronchitis. Chronic cough may also be psychological. Other rare causes of chronic cough may include lung cancer, congestive heart failure, tuberculosis (TB), tracheal or bronchial malacia, bronchial lesion, hodgkin’s disease, hyperthyroidism, Zenker’s diverticulum, cancer of pharynx or sinus, carcinoid tumor, compression of trachea or bronchi, pulmonary congestion from heart disease, parasites (that migrate to the lungs), pulmonary embolism, cardiac arrhythmias, vocal cord dysfunction, pleural disease or foreign body in the auditory canal.
Many pathological mechanisms can be responsible for cough. Sometimes a combination of these mechanisms is responsible for cough, which may lead to treatment-refractory cough. This form of cough responds only if all the conditions, responsible for the persistent cough, are correctly identified and appropriately treated.
Accurate diagnosis of all the conditions responsible for cough is crucial for proper management of chronic cough. It involves a comprehensive evaluation of the patient that may include detailed medical history, careful physical examination, lung function tests, chest X-ray, laboratory investigations, esophageal endoscopy, allergy testing, methacholline challenge, 24 hour pH probe, nasopharyngolaryngoscopy, CT chest and sinus and bronchoscopy.
The treatment of cough involves antitussive drugs, protussive drugs, antibiotics, corticosteroids, bronchodilators with diet control and environmental control depending on the conditions triggering cough. Comprehensive management of all the underlying conditions simultaneously is the key to an effective treatment of chronic cough.