Causes of chronic cough
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Common Causes of Chronic Cough
Chronic cough, defined as a cough lasting more than 8 weeks in adults, is most often caused by a few key conditions. The most common causes include asthma (especially cough variant asthma), upper airway cough syndrome (also known as postnasal drip syndrome or rhinosinusitis), gastroesophageal reflux disease (GERD), and nonasthmatic eosinophilic bronchitis. These four conditions account for the majority of chronic cough cases in various populations worldwide, including China and Japan, and are often referred to as the "pathogenic triad" when asthma, postnasal drip, and GERD are present together 1234+2 MORE.
Additional and Environmental Causes
Other important causes include chronic obstructive pulmonary disease (COPD), bronchiectasis, pulmonary fibrosis, and atopic cough. Environmental factors such as cigarette smoking, exposure to secondhand smoke, and air pollution (especially particulates) are also significant contributors to chronic cough. Occupational exposures to irritants and allergens can trigger or worsen chronic cough, and these factors should be considered during evaluation 189.
Rare and Less Common Causes
While most cases are due to the common causes listed above, rare causes of chronic cough do exist. These include protracted bacterial bronchitis, somatic cough syndrome, diffuse panbronchiolitis, obstructive sleep apnea syndrome, and interstitial lung disease. Drug-induced chronic cough, most notably from angiotensin-converting enzyme inhibitors (ACEIs), is another rare but important cause. Other medications, such as angiotensin receptor blockers and certain other drugs, have also been reported to cause chronic cough 510.
Diagnostic Considerations
Chronic productive (wet) cough may point toward conditions like bronchiectasis, chronic bronchitis, or immunodeficiency, and may require a slightly different diagnostic approach. In children, the most common causes are asthma, protracted bacterial bronchitis, and upper airway cough syndrome. For all patients, a thorough history, physical examination, and targeted investigations (such as spirometry, chest imaging, and sometimes bronchoscopy) are essential to identify the underlying cause 68.
Idiopathic Chronic Cough
In some patients, no clear cause is found even after thorough evaluation. These cases are labeled as idiopathic chronic cough. Changes in nerve sensitivity and airway inflammation may play a role in these cases, and treatment may focus on desensitizing the cough reflex .
Conclusion
Chronic cough is most often caused by asthma, upper airway cough syndrome, GERD, and eosinophilic bronchitis, but a wide range of other conditions—including environmental exposures, rare diseases, and certain medications—can also be responsible. A careful and systematic approach is needed to identify the cause and guide effective treatment.
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