Upper airway cough syndrome (UACS) (formerly called postnasal drip)
Common in all ages; may be due to allergic or non-allergic rhinitis or sinusitis.
Chronic rhinosinusitis
May present with nasal congestion, drainage, and cough.
Chronic obstructive pulmonary disease (COPD)
Often associated with a history of smoking; chronic bronchitis is a common subtype with cough and sputum.
Asthma (can present as cough-variant asthma)
May persist into older age or develop later in life.
Interstitial lung disease
Cough is often dry and persistent, with dyspnea; idiopathic pulmonary fibrosis is more common in older adults.
Lung cancer
Should be considered especially in smokers or those with red-flag symptoms like hemoptysis or weight loss.
Bronchiectasis
Chronic productive cough; may be due to infections or immune deficiencies.
Infections
Acute or subacute cough: pneumonia, pertussis, atypical pathogens like Mycoplasma or Chlamydia.
Gastroesophageal reflux disease (GERD)
Common cause of chronic cough, especially if nocturnal or associated with hoarseness or throat clearing.
Laryngopharyngeal reflux (LPR)
May present without heartburn, primarily with cough, hoarseness, or globus sensation.
Heart failure (especially left-sided)
Cough may be worse at night or with exertion; may be accompanied by orthopnea or paroxysmal nocturnal dyspnea.
ACE inhibitor–induced cough
Occurs in 5–20% of patients on ACE inhibitors; typically dry and persistent.
Smoking (active or passive)
Major risk factor for chronic bronchitis, COPD, lung cancer.
Occupational or environmental exposures
Dusts, fumes, allergens, or irritants.
Medication-related
Aside from ACE inhibitors: beta-blockers may exacerbate asthma.
Foreign body aspiration
Uncommon but possible in elderly, especially with impaired swallowing or cognition.
Psychogenic cough
Diagnosis of exclusion; less common in older adults.
Obstructive sleep apnea (OSA)
Can be associated with nocturnal cough, GERD, or upper airway irritation.