Red flags
- Haemoptysis, unintentional weight loss, night sweats - malignancy/TB until excluded, especially in a smoker
- New cough age >=40 with smoking history - low threshold for CXR +/- CT
- Progressive dyspnoea, stridor, or voice change accompanying the cough
- Cough with recurrent pneumonia in the same lobe - suspect an obstructing endobronchial lesion
- Aspiration risk (dysphagia, neurological disease) - recurrent aspiration pneumonitis pattern
Differential by mechanism
Chronic cough (>8 weeks) - the "big three" account for most cases
- Upper airway cough syndrome (post-nasal drip) - rhinitis/sinusitis driven, throat clearing, worse lying flat
- Asthma/cough-variant asthma - worse at night/exercise/cold air, may have no wheeze
- GORD - can be silent (no heartburn), worse post-meal/lying flat, sometimes with hoarseness
Other important causes
- ACE-inhibitor cough - dry, any time after starting (weeks-months), resolves within weeks of cessation - always check the medication list first
- Chronic bronchitis/COPD - productive, smoking history
- Bronchiectasis - copious purulent sputum, recurrent infections
- Post-infectious cough - self-limiting, follows a viral URTI, can persist 3-8 weeks
- Interstitial lung disease - dry cough + progressive dyspnoea + fine crackles
- Malignancy - especially with red flags above
- Refractory/unexplained chronic cough - persists despite addressing the above, thought to reflect cough hypersensitivity syndrome
Focused history
- Duration (acute <3 weeks, subacute 3-8 weeks, chronic >8 weeks) - determines work-up urgency/breadth
- Sputum - colour, volume, chronicity (bronchiectasis, chronic bronchitis)
- Triggers - exercise, cold air, lying flat, eating, post-nasal symptoms
- Full medication review - ACE-inhibitors specifically
- Smoking history (pack-years), occupational/environmental exposures
- Associated symptoms - reflux, wheeze, nasal symptoms, weight loss
Focused examination
- Chest auscultation - wheeze (asthma), crackles (ILD, bronchiectasis, pneumonia), reduced air entry
- Nasal examination/post-nasal drip signs, oropharyngeal cobblestoning
- Clubbing (bronchiectasis, ILD, malignancy), lymphadenopathy
- General - weight, signs of systemic illness
Investigation strategy
- CXR - first-line investigation for any chronic cough, especially with red flags or smoking history
- Spirometry +/- bronchial provocation testing - if asthma suspected and CXR unremarkable
- Trial-based diagnosis is standard practice - empirical treatment trial for the most likely of the "big three" (e.g. PPI trial for suspected reflux) rather than exhaustive upfront testing, if red flags absent
- CT chest, bronchoscopy - if CXR abnormal, red flags present, or cough remains unexplained after standard work-up
- Sputum culture if productive/suspected bronchiectasis or chronic infection
Management
A. Treat the identified/most likely cause
- ACE-inhibitor cough - stop the drug, switch to an ARB; expect resolution within days-weeks
- Upper airway cough syndrome - intranasal corticosteroid/antihistamine, treat underlying rhinitis/sinusitis
- Asthma/cough-variant asthma - inhaled corticosteroid +/- bronchodilator trial
- GORD-related cough - PPI trial (typically a longer course, e.g. 8-12 weeks, needed to assess cough response specifically)
- Post-infectious cough - usually self-limiting; reassurance, symptomatic relief
B. Refractory/unexplained chronic cough (persists despite addressing the above)
- Consider speech pathology input (cough suppression techniques) - good evidence for symptom reduction
- Gefapixant (P2X3 receptor antagonist) - emerging option for refractory or unexplained chronic cough where standard causes have been excluded/treated without response; taste disturbance is the main tolerability issue
- Low-dose neuromodulators (e.g. gabapentin, low-dose morphine in selected refractory cases) - used off-label, reflects the cough hypersensitivity model
C. General
- Smoking cessation in all smokers with chronic cough
- Avoid reflexive antibiotics for a non-productive/non-infective chronic cough
Traps
- Missing an ACE-inhibitor as the cause because the cough started months after the drug was initiated - the latency can be long
- Treating chronic cough with repeated antibiotic courses without a clear infective indication
- Skipping the CXR in an older smoker because "it's probably just reflux"
- Assuming GORD-related cough will respond within days - it often needs a prolonged PPI trial before concluding it isn't the cause
- Labelling chronic cough as "psychogenic" or "idiopathic" before systematically working through upper airway, asthma, and reflux causes
Talk track
1. Check the medication list before ordering anything
- "An ACE-inhibitor cough can start months into treatment - I check the drug chart before I request a single test."
2. The big three, trialled in sequence, solve most chronic cough
- "Post-nasal drip, asthma, and reflux explain the majority of chronic cough - I work through them systematically with treatment trials before chasing something exotic."
8 of 8 sections written · drafted 2026-09-14