Step 1 of 14
Presentation & Duration
Classify by duration — acute <3 wk · subacute 3–8 wk · chronic >8 wk (this chapter)
The first and most decisive question in any cough is how long it has lasted, because duration, more than any other feature, sorts the differential. Acute cough (under 3 weeks) is dominated by viral upper-respiratory infection, acute bronchitis, influenza, COVID-19, and pneumonia — self-limiting or infective, and managed accordingly. Subacute cough (3–8 weeks) is most often post-infectious, the lingering cough after a resolved infection, but also captures pertussis, a first presentation of asthma, sinusitis, and bronchitis. Chronic cough (over 8 weeks) is the subject of this chapter and a different problem altogether.
Crossing the eight-week threshold reframes the clinical task: the question is no longer "which infection" but "which treatable trait, or which cough hypersensitivity, is driving a cough that should have stopped and has not". The duration cut-off is not arbitrary — it marks the point at which post-infectious and self-limiting causes have largely declared themselves, and a systematic, multidisciplinary evaluation becomes worthwhile. Establishing that a cough is genuinely chronic is therefore the gateway to the entire algorithm, and it is worth pinning down the true onset and time-course before launching the workup.
- Acute <3 wk — viral URI, acute bronchitis, influenza, COVID-19, pneumonia (mostly self-limiting/infective)
- Subacute 3–8 wk — post-infectious cough, pertussis, asthma, sinusitis, bronchitis
- Chronic >8 wk — the full treatable-traits / cough-hypersensitivity evaluation
- Duration reframes the differential away from infection toward treatable traits
Key statistics
Chronic = over 8 weeks
>8 weeks defines chronic cough
The 8-week threshold is the gateway to the chronic-cough algorithm — it marks where self-limiting and post-infectious causes have largely declared themselves.
Cough by duration
Duration is the first and most decisive sort
Acute
< 3 weeks — viral URI, acute bronchitis, influenza, COVID-19, pneumonia
mostly self-limiting / infective
Subacute
3–8 weeks — post-infectious cough, pertussis, asthma, sinusitis
Chronic
> 8 weeks — treatable traits + cough hypersensitivity
the full evaluation in this chapter
★ High-yield pearls (chapter-wide)
- Chronic cough is defined by duration — over 8 weeks — and that single number reframes the differential away from acute infection toward the treatable traits and cough hypersensitivity.
- A chest radiograph is mandatory in every chronic cough, and an ACE-inhibitor must be stopped before anything else — the two cheapest, highest-yield steps in the whole algorithm.
- In ENT practice, flexible nasolaryngoscopy is done early — it screens for malignancy, vocal-fold pathology, paradoxical fold motion, and the laryngeal signs of reflux and sensory neuropathy in one look.
- Upper-airway cough syndrome, reflux, asthma and non-asthmatic eosinophilic bronchitis, and cough hypersensitivity account for the great majority of chronic cough with a normal chest X-ray.
- Most chronic cough is multifactorial — finding one treatable trait does not excuse you from looking for the others, and incomplete response usually means a second contributor is still active.
- Non-asthmatic eosinophilic bronchitis coughs without wheeze, has normal spirometry and a normal airway-responsiveness test, and is caught only by sputum eosinophils or FeNO — yet it responds beautifully to inhaled steroids.
- Cough hypersensitivity syndrome is the modern unifying concept — laryngeal hypersensitivity and central sensitisation, often post-viral, with the patient who says 'everything triggers my cough': talking, laughing, eating, perfume, cold air.
- Neurogenic cough is a diagnosis of exclusion that responds to neuromodulators — gabapentin, pregabalin, or amitriptyline — not to more acid suppression or more antihistamine.
- Speech-language-pathology cough-suppression therapy is a core treatment, not an afterthought — it durably reduces refractory cough and is paired with, not replaced by, neuromodulators.
- Refractory chronic cough (a treatable trait found and treated, but cough persists) and unexplained chronic cough (no cause found) are distinct entities — and both are the natural home of P2X3 antagonists such as gefapixant.
Evidence base
2 sources- HIGH
Morice AH, Millqvist E, Smith JA · Eur Respir J · 2020Clinical practice guidelinePMID 31515408
The European Respiratory Society guideline defining chronic cough (>8 weeks), the diagnostic evaluation, the treatable traits, cough hypersensitivity, and the role of neuromodulators and speech therapy.
- HIGH
Pratter MR · Chest · 2006Clinical practice guidelinePMID 16428693
ACCP overview establishing the anatomic-diagnostic protocol and the common treatable causes of chronic cough — upper-airway cough syndrome, asthma, non-asthmatic eosinophilic bronchitis, and reflux.
Decision tree
Duration sets the frame; the red-flag screen, a mandatory chest X-ray, and the wet-versus-dry fork structure the workup. The treatable traits and the hypersensitivity phenotype route the dry cough to one of ten pathways.