1. Chronic bronchitis / COPD
   • Especially with smoking, biomass-fuel exposure, occupational dust/fumes
   • Often daily mucoid sputum, breathlessness, wheeze
2. Bronchiectasis
   • Persistent cough with moderate to large amounts of thick or purulent sputum
   • Recurrent chest infections, fever during exacerbations, hemoptysis, crackles, sometimes clubbing
   • Requires HRCT chest for confirmation. Persistent productive cough and recurrent infections are typical features. Harrison’s Principles of Internal Medicine, 22e.
3. Chronic rhinosinusitis with postnasal drip
   • Nasal blockage/discharge, throat clearing, sensation of mucus dripping in the throat
   • Can cause chronic cough and sometimes expectoration of swallowed nasal secretions.
4. Asthma, including cough-predominant asthma
   • Variable wheeze, chest tightness, nocturnal or early-morning symptoms
   • Sputum may be scanty, often clear or whitish.
5. Non-asthmatic eosinophilic bronchitis
   • Chronic cough with sputum eosinophilia but normal spirometry and no typical asthma-type airway hyperreactivity.
6. Gastroesophageal reflux disease (GERD) or laryngopharyngeal reflux
   • Heartburn, sour regurgitation, hoarseness, cough after meals or when lying down
   • May coexist with other respiratory causes.
7. Pulmonary tuberculosis
   • Must be considered, particularly in TB-endemic settings.
   • Suggestive features: fever, night sweats, weight loss, reduced appetite, hemoptysis, TB contact. Chest imaging and sputum testing are needed when suspected. Harrison’s Principles of Internal Medicine, 22e.
8. Chronic or recurrent airway infection
   • Persistent bacterial infection, chronic suppurative lung disease, or atypical mycobacterial infection.
   • Purulent, foul-smelling sputum and repeated antibiotic-treated infections increase suspicion.
9. Lung cancer or an endobronchial lesion
   • More concerning in older adults or smokers, or with new change in longstanding cough, hemoptysis, weight loss, recurrent pneumonia in the same area, or hoarseness.
10. Interstitial lung disease, heart failure, or aspiration-related disease

• Less typical causes of long-standing sputum, but consider if there is exertional breathlessness, orthopnea/leg swelling, swallowing difficulty, or recurrent aspiration.

1. Medication-related cough

• ACE inhibitors usually cause a dry cough rather than expectoration, so they are less likely to explain significant sputum.

Useful initial work-up

• History: smoking/exposures, volume and color of sputum, wheeze, fever, weight loss, reflux/nasal symptoms, TB contact, recurrent infections
• Examination and oxygen saturation
• Chest X-ray: chronic cough generally warrants imaging
• Spirometry with bronchodilator: COPD/asthma
• Sputum Gram stain/culture, and TB testing where indicated
• HRCT chest if bronchiectasis or another structural lung disease is suspected
• CBC, eosinophil count, and other targeted tests as clinically indicated