What are the common causes and management strategies for a chronic cough lasting more than 8 weeks?

Common Causes of Chronic Cough (>8 Weeks)

The most common causes of chronic cough lasting more than 8 weeks are upper airway cough syndrome (UACS) from rhinosinus conditions, asthma, gastroesophageal reflux disease (GERD), and nonasthmatic eosinophilic bronchitis, either alone or in combination. 1

Primary Etiologies

Based on prospective studies across four continents involving 2,220 patients, the following represent the established causes of chronic cough:

Most Common Causes (Account for >90% of cases)

• Upper Airway Cough Syndrome (UACS): Previously called postnasal drip syndrome, this encompasses various rhinosinus conditions and represents one of the top three causes 1

• Asthma: Including cough-variant asthma, this is a leading cause particularly when cough worsens at night, with cold air exposure, or with exercise 2, 3

• Gastroesophageal Reflux Disease (GERD): A major contributor, though acid suppression alone is no longer recommended as sole therapy 1

• Nonasthmatic Eosinophilic Bronchitis (NAEB): An important but less common cause that requires specific identification 1

• Combinations of the above four conditions: Many patients have multiple simultaneous causes 1

Medication-Induced Causes

• ACE Inhibitor-induced cough: Can resolve within days to 2 weeks (median 26 days) after discontinuation 2

• Sitagliptin: Should also be discontinued if present to assess if responsible for cough 1

Geographic Variation

• Atopic cough: More commonly reported in Asian countries as a distinct entity 1

Less Common But Important Causes

Environmental and Occupational

• Smoking-related chronic bronchitis: Can resolve within 4 weeks of cessation in most patients 2

• Environmental and occupational exposures: Should be systematically evaluated in all patients 1

Uncommon Pulmonary Disorders

When common causes are excluded, consider these uncommon etiologies (each representing the presenting symptom in >50% of affected patients): 1

• Airway abnormalities: Tracheobronchomalacia, airway stenosis/strictures, tracheobronchopathia osteoplastica, Mounier-Kuhn syndrome
• Airway deposits: Tracheobronchial amyloidosis
• Foreign bodies: Airway foreign bodies, broncholithiasis
• Interstitial diseases: Lymphangioleiomyomatosis, pulmonary Langerhans cell histiocytosis
• Connective tissue diseases: Rheumatoid arthritis, scleroderma, Sjögren syndrome, systemic lupus erythematosus
• Vasculitis: Wegener granulomatosis, giant cell arteritis
• Inflammatory bowel disease: Crohn disease, ulcerative colitis

Critical Red Flags Requiring Immediate Evaluation

These findings mandate urgent investigation for life-threatening conditions: 1

• Hemoptysis
• Smoker >45 years with new cough, change in cough, or coexisting voice disturbance
• Adults aged 55-80 years with 30 pack-year smoking history who currently smoke or quit within past 15 years
• Prominent dyspnea, especially at rest or at night
• Hoarseness
• Systemic symptoms: Fever, weight loss, night sweats
• Peripheral edema with weight gain
• Trouble swallowing when eating or drinking
• Vomiting
• Recurrent pneumonia
• Abnormal respiratory exam and/or abnormal chest radiograph coinciding with cough duration

Refractory Chronic Cough

When cough remains unexplained after systematic evaluation and adequate therapeutic trials, consider: 1

• Referral to a well-recognized cough clinic for specialized evaluation
• Cough hypersensitivity syndrome as an underlying mechanism
• Gabapentin trial starting at 300mg once daily, escalating to maximum 1,800mg daily in divided doses 2
• Multimodality speech pathology therapy as an alternative approach 2

Common Pitfalls to Avoid

• Assuming single etiology: Up to 40% of patients have multiple simultaneous causes requiring combination therapy 1, 4
• Using acid suppression alone for GERD-related cough: This is no longer recommended; comprehensive GERD management is required 1
• Premature diagnosis of idiopathic cough: Only 8% remain unexplained after proper systematic evaluation 1
• Ignoring medication review: ACE inhibitors and sitagliptin must be discontinued before pursuing extensive workup 1, 2
• Failing to use validated cough severity tools: These should be routinely employed to objectively assess treatment response 1