Chronic cough causes
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Common Causes of Chronic Cough: Asthma, Postnasal Drip, and GERD
Asthma, postnasal drip syndrome (also called upper airway cough syndrome), and gastroesophageal reflux disease (GERD) are the most frequent causes of chronic cough in adults. These three conditions, often referred to as the "pathogenic triad," are responsible for the vast majority of chronic cough cases, either alone or in combination, accounting for over 90% of cases in some studies Palombini1999Chung2008Michaudet2017+1 MORE. Asthma-related cough can occur even without classic wheezing, while postnasal drip and GERD may present with cough as the main or only symptom Palombini1999Chung2008Michaudet2017+1 MORE.
Other Common and Regional Causes: Eosinophilic Bronchitis and Atopic Cough
Eosinophilic bronchitis and atopic cough are also recognized as important causes, especially in certain populations. In China, for example, cough variant asthma, upper airway cough syndrome, eosinophilic bronchitis, and atopic cough together account for the majority of chronic cough cases . These conditions can be distinguished from asthma by the absence of airway hyperresponsiveness in eosinophilic bronchitis and by specific clinical features in atopic cough Lai2013Chung2008.
Environmental, Occupational, and Lifestyle Factors
Environmental and occupational exposures, such as tobacco smoke, air pollution, and workplace irritants, are significant contributors to chronic cough. Both direct and secondhand smoke, as well as exposure to particulates and other irritants, can trigger or worsen chronic cough Chung2008Tarlo2016. Occupational diseases and environmental allergies should be considered, especially when there is a relevant exposure history .
Chronic Productive Cough: Bronchiectasis, Chronic Bronchitis, and Immunodeficiency
For patients with a chronic productive (wet) cough, conditions like bronchiectasis, chronic bronchitis, asthma, eosinophilic bronchitis, and immunodeficiency are common causes. Protracted bacterial bronchitis, though more recognized in children, can also be seen in adults and may respond to specific antibiotic therapy Martin2015Lai2021Michaudet2017.
Rare Causes of Chronic Cough
While most cases are due to common conditions, rare causes should be considered if initial treatments fail. These include protracted bacterial bronchitis, somatic cough syndrome, diffuse panbronchiolitis, obstructive sleep apnea syndrome, and interstitial lung disease. Rare causes can involve multiple body systems and may require advanced diagnostic tests like high-resolution CT scans or bronchoscopy for identification .
Drug-Induced Chronic Cough
Certain medications, especially angiotensin-converting enzyme inhibitors (ACE inhibitors), are well-known to cause chronic cough. Other drugs, such as angiotensin receptor blockers, omeprazole, and leflumide, have also been implicated. A careful medication history is essential, and improvement after stopping the suspected drug supports the diagnosis Ding2020Michaudet2017.
Neuropathic and Idiopathic Chronic Cough
Some patients experience chronic cough without an identifiable cause, termed idiopathic cough. There is growing evidence that chronic cough can be a neuropathic disorder, where nerve dysfunction leads to heightened cough reflex sensitivity. This may explain why some patients do not respond to standard treatments and may benefit from therapies used for neuropathic pain, such as gabapentin or amitriptyline Chung2013Chung2008.
Conclusion
Chronic cough is most often caused by asthma, postnasal drip syndrome, and GERD, but other conditions like eosinophilic bronchitis, atopic cough, environmental exposures, and certain medications are also important. Rare causes and neuropathic mechanisms should be considered when common causes are excluded. A thorough evaluation, including history, physical examination, and targeted investigations, is essential for effective management and relief of symptoms Palombini1999Chung2008Lai2013+7 MORE.
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