REASONING GP · Clinical algorithm · Quick reference

Chronic cough in adults — triage and diagnostic approach

Cough lasting 8 weeks or more. Two quick wins first — stop any ACE inhibitor and get a chest X-ray — then exclude cancer and TB, then work the treatable triad with adequate trial lengths.
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Adults≥8 weeksDiagnosis firstv1.0 · Sep 2026
Core rule. Three steps, in order. 1. Two quick wins: stop any ACE inhibitor — it causes a dry cough in 10–15% and can start at any time on treatment, resolving in 1–4 weeks — and a chest X-ray is mandatory at first presentation. 2. Exclude cancer and TB before any symptomatic treatment. 3. Work the treatable triad — upper-airway cough syndrome, reflux, and cough-variant asthma or eosinophilic bronchitis — one at a time, each for its full trial length, because a trial stopped at 2 weeks has not been tried. Never label "smoker's cough" without a CXR.
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On presentation: is this an emergency now? Stop the consultation and call 999 if any of these is present
Stridor, or cough with upper-airway obstruction — tracheal compression, vocal cord tumour, anaphylaxis · massive haemoptysis (about 200 mL or more, or brisk ongoing bleeding) · breathlessness at rest with SpO₂ below 92%, exhaustion or cyanosis · cough with chest pain and haemodynamic compromise, or with syncope · suspected anaphylaxis with swelling of lips or tongue and urticaria · sepsis features with cough and fever. ABCDE, observations including SpO₂, exact onset, hand over. Do not delay transfer for a chest X-ray or spirometry.
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Define the cough in four lines Duration sets the pathway; the drug chart and the smoking history change it

Duration

Under 3 weeks is acute; 3–8 weeks subacute — usually post-infectious, and consider pertussis where there is a paroxysmal or whooping cough or post-tussive vomiting; 8 weeks or more is chronic, which is this pathway. A cough that has simply never settled after a viral illness is still chronic at 8 weeks and still needs the CXR.

Drugs — check before anything else

ACE inhibitors: dry tickly cough in 10–15%, a class effect not dose-related, able to begin months into treatment, and resolving in 1–4 weeks after stopping — switch to an ARB. Also sitagliptin, and any inhaler causing throat irritation. Stop the ACE inhibitor before investigating further: it is the single commonest reversible cause.

Character and triggers

Dry and tickly (ACE inhibitor, cough-variant asthma, upper-airway cough syndrome, cough hypersensitivity) · productive (bronchiectasis, chronic infection) · worse at night (asthma, reflux, post-nasal drip) · triggered by cold air, exercise, laughter or perfume (hyperreactivity, hypersensitivity) · worse lying flat, after meals or alcohol (reflux) · seasonal (allergic rhinitis).

Context

Pack-years and vaping · occupational exposure — flour and grain dust, isocyanates in spray painting, wood dust, laboratory animals; ask whether the cough improves away from work · TB risk: country of birth, contacts, homelessness, immunosuppression · asbestos · atopy and hay fever · heartburn · immunosuppression, HIV, chemotherapy or long-term steroids.
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Red-flag screen: trigger → concern → destination → what to do before handover One row is enough; do not add up reassuring features
Trigger / red flagLeading concern · destinationDo now · do not delay
Stridor, or cough with upper-airway obstruction; massive haemoptysis; breathlessness at rest with SpO₂ below 92%; or sepsis features with cough and fever. Airway obstruction · major haemoptysis · pneumonia with sepsis
999 now		 Sit the patient up, controlled oxygen, observations with SpO₂, and transfer. Do not attempt to examine a stridulous throat. Do not wait for a chest X-ray or spirometry to make the decision — both are hospital steps once the airway or oxygenation is the problem.
Cough with fever, night sweats and weight loss, or three weeks of cough in someone from a high-incidence country, a contact of TB, homeless, in prison or immunosuppressed; haemoptysis with these features. Tuberculosis
Urgent CXR and three sputum samples for AFB; same-day respiratory or TB service discussion		 Arrange an urgent chest X-ray plus three sputum samples for acid-fast bacilli, and notify or discuss with the TB service — do not treat as a chest infection and review. Ask about household contacts and BCG. Isolated night sweats without cough or weight loss are far less specific; it is the combination that matters.
Immunosuppression with a new or changed cough — HIV, chemotherapy, biologics, long-term steroids, transplant, asplenia; particularly with breathlessness, fever or hypoxia. Pneumocystis · fungal infection · atypical or opportunistic pneumonia · TB
Same-day assessment; 999 if hypoxic or septic		 Lower the threshold for everything: same-day CXR, FBC and SpO₂ on exertion, and speak to the specialist team. A near-normal examination with exertional desaturation is the classic Pneumocystis presentation — do not reassure on a clear chest. Neutropenic fever is a 999.
Cough with dysphagia, aspiration or a hoarse voice; coughing during or after swallowing; recurrent lower lobe consolidation; a neurological diagnosis; or persistent hoarseness beyond 3 weeks. Aspiration · pharyngeal pouch · oesophageal or laryngeal pathology
Urgent CXR, speech and language assessment, and ENT or upper GI referral		 Persistent hoarseness in a smoker aged 45 or over is an NG12 route (below), not a routine ENT letter. Coughing with swallowing is an aspiration risk that needs a swallow assessment before dietary advice. Recurrent consolidation in the same lobe needs imaging and a structural explanation.
Chronic productive cough with daily sputum, recurrent chest infections, haemoptysis in a known chronic lung disease, or coarse crackles and clubbing; or breathlessness with fine bibasal crackles and exertional desaturation. Bronchiectasis · chronic pulmonary infection · interstitial lung disease
Urgent CXR; respiratory referral — urgently where ILD is suspected		 Send sputum culture (including for mycobacteria where there are risk factors), FBC, and immunoglobulins where bronchiectasis is likely. A normal chest X-ray does not exclude bronchiectasis or ILD — both need CT, so refer on the clinical picture rather than on the film.
Cough with cardiac features: orthopnoea, paroxysmal nocturnal dyspnoea, ankle oedema, a raised JVP or bibasal crackles; a nocturnal cough with known ischaemic heart disease or atrial fibrillation. Heart failure presenting as cough
Same-day assessment if breathless at rest; otherwise NT-proBNP and ECG		 Send NT-proBNP with an ECG (NG106): 400–2000 ng/L needs echocardiography within 6 weeks, above 2000 ng/L within 2 weeks. Do not start or increase a diuretic and review at a distance in a patient breathless at rest. Remember the cough may be the ACE inhibitor prescribed for the heart failure.
NG12 criteria: haemoptysis at 40 or over · 40 or over with unexplained cough plus another unexplained symptom (fatigue, breathlessness, chest pain, weight loss, appetite loss) or who has ever smoked or had asbestos exposure · a chest X-ray suggesting lung cancer · clubbing, supraclavicular or persistent cervical nodes, thrombocytosis · persistent hoarseness at 45 or over · dysphagia at any age. Lung cancer · mesothelioma · laryngeal or oesophageal cancer
Urgent chest X-ray within 2 weeks; urgent suspected-cancer referral within 2 weeks if it suggests cancer, or directly for haemoptysis at 40+ · urgent ENT for hoarseness at 45+ · urgent OGD for dysphagia · NICE NG12		 A normal chest X-ray does not close the question — with persisting or unexplained symptoms, refer on the urgent suspected-cancer route anyway and state the normal film in the request. Do not attribute a new or changed cough in a smoker aged 40 or over to "smoker's cough", COPD or reflux without imaging. Record the pack-years and asbestos history in the referral.
Safety rule. A chest X-ray is mandatory at first presentation of a chronic cough, and a normal film excludes neither cancer, bronchiectasis nor ILD. Stop the ACE inhibitor before investigating further. Do not treat the triad without first excluding cancer and TB, and do not judge a triad trial that has run for less than its full length — 4–6 weeks for upper-airway, 8–12 weeks for reflux, 8 weeks for inhaled steroid.
Colour is semantic: red = emergency now · amber = same-day or urgent assessment · blue = define/assess · green = primary-care management · purple = uncertain / specialist route (including 2WW). Continued on page 2: investigation, classification, cause classifier, routine referral, primary-care management, endpoint.
REASONING GP · Chronic cough in adults — triage and diagnostic approach
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Assessment and investigation The chest X-ray is not optional, and the drug chart is part of the examination

Assess, investigate, then read it together

Examine: BMI and weight trend; RR, SpO₂ at rest and after exertion, pulse, temperature; voice and stridor; nose, post-nasal space and throat; chest for wheeze, crackles (fine or coarse) and focal signs; clubbing, supraclavicular and cervical nodes; JVP, heart sounds and oedema. Then: chest X-ray in everyone at first presentation · spirometry with reversibility, and FeNO or a peak-flow diary where asthma is possible (NG245) · FBC with eosinophil count · sputum culture, and AFB × 3 where TB is possible · NT-proBNP and ECG where cardiac · U&E, TFTs · consider allergy testing where rhinitis is prominent. Then read it: abnormal CXR — respiratory or the NG12 route, not a triad trial · obstructive spirometry with reversibility, or raised FeNO — asthma or cough-variant asthma · raised eosinophils with normal spirometry — eosinophilic bronchitis, steroid-responsive · normal everything with a dry trigger-sensitive cough — cough hypersensitivity, once the triad has been treated. Do not start a trial before the CXR, accept normal spirometry as excluding asthma, or label hypersensitivity at a first visit.
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Classify: three exits, not two "Smoker's cough" and "post-viral" are not endpoints at 8 weeks

Serious cause likely

Any red flag, an abnormal CXR, TB features, immunosuppression, aspiration, suspected bronchiectasis or ILD, cardiac features, or an NG12 criterion. Output: destination with date, CXR result, pack-years and asbestos history, SpO₂, tests sent.

Treatable cause, managed in primary care

Normal CXR, no red flag, a coherent triad diagnosis — or an ACE inhibitor stopped. Output: the named cause, the treatment with its full trial length, the expected response, the review date.

Unexplained after adequate trials

Cough persisting after a normal CXR and adequately long triad trials, or a mixed picture with partial responses. Output: list each trial with drug, dose and duration, state the uncertainty, take the §6 route.
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Cause classifier: the treatable triad, then the rest Only once the CXR is normal and cancer and TB are excluded
ACE inhibitor cough, then upper airway cough syndromeACE inhibitor: the first thing to exclude and the easiest to fix — dry and tickly, in 10–15% of users, a class effect that is not dose-related and can begin months into treatment. Stop it and switch to an ARB, expecting resolution in 1–4 weeks (occasionally up to 3 months); never investigate a cough on an ACE inhibitor before stopping it. Upper airway cough syndrome (post-nasal drip) is then the commonest cause: throat clearing, a dripping sensation, rhinorrhoea, nasal obstruction, cobblestoned pharynx, from allergic or non-allergic rhinitis or sinusitis — an intranasal corticosteroid ± antihistamine with saline irrigation, technique checked, allowing 4–6 weeks. Reflux and laryngopharyngeal reflux — second commonest and often without heartburn (silent reflux): worse after meals, lying flat or with alcohol, with throat clearing and hoarseness. Treat with a PPI twice daily before meals for a minimum of 8–12 weeks plus reflux measures — a 4-week trial is not a trial; alarm features go to the NG12 upper GI route. Cough-variant asthma: cough as the only symptom, worse at night, triggered by cold air, exercise or allergens — and spirometry is often normal, so use FeNO, a peak-flow diary or reversibility, and treat with an inhaled corticosteroid for at least 8 weeks. Eosinophilic bronchitis: raised eosinophils with normal spirometry and no hyperreactivity — also steroid-responsive.
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Refer routinely from this consultation Not same-day — the cases that leave by letter; §7 is what primary care does today
Cough unexplained after a normal CXR and adequate triad trials → respiratory, listing each trial with drug, dose and duration so it is not repeated · suspected bronchiectasis, ILD or chronic pulmonary infection → respiratory for CT, urgently for ILD, regardless of a normal chest X-ray · suspected asthma where objective testing is inconclusive or unavailable → respiratory or a diagnostic hub (NG245); occupational asthma → an occupational lung service · persistent laryngopharyngeal reflux or a suspected structural laryngeal cause → ENT · reflux not responding to 8–12 weeks of twice-daily PPI → gastroenterology (CG184) · refractory cough or cough hypersensitivity → a cough clinic or speech and language therapy · suspected heart failure on NT-proBNP → the heart-failure pathway (NG106) · COPD at MRC grade 3+ → pulmonary rehabilitation (NG115).
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The only decisions that belong in this consultation What primary care treats today — one trial at a time, each for its full length
The two quick wins, then the three trials — one at a time, each for its full lengthQuick wins first: stop the ACE inhibitor and switch to an ARB, expecting resolution in 1–4 weeks, and arrange the chest X-ray, mandatory at first presentation, with smoking-cessation support at the same visit. Do not start a trial before the CXR is back, and never run two at once — you will not know which worked. 1 · Upper airway: an intranasal corticosteroid (for example mometasone, two sprays once daily) ± an oral antihistamine, with saline irrigation — demonstrate the spray technique (head forward, away from the septum), as poor technique is the usual reason for failure, and allow 4–6 weeks. 2 · Reflux: a PPI twice daily before meals for a minimum of 8–12 weeks (for example omeprazole 20–40 mg twice daily) plus reflux measures — weight loss, smaller evening meals, nothing 3 hours before bed, head-of-bed elevation, less alcohol and caffeine; a once-daily 4-week course is not an adequate trial for cough. 3 · Asthma or eosinophilic bronchitis: an inhaled corticosteroid for at least 8 weeks (for example beclometasone 200 micrograms twice daily via a spacer) with technique checked, adding a short-acting beta agonist only if there is wheeze, and confirming objectively where possible with FeNO, reversibility or a peak-flow diary (NG245). Also: Bronchiectasis — daily sputum, recurrent infections, coarse crackles, clubbing; needs CT, as the CXR is often normal. COPD — post-bronchodilator FEV₁/FVC below 0.7 with exposure history (NG115). ILD — fine bibasal crackles, clubbing, exertional desaturation, restrictive spirometry. Pertussis — paroxysms, whoop, post-tussive vomiting. Cough hypersensitivity — a sensitised reflex triggered by talking, cold air or perfume with no structural cause, diagnosed only after the triad has been properly treated and managed with cough-suppression therapy. Do not conclude: "smoker's cough" without a CXR · "post-viral" at 8 weeks · "reflux" after 4 weeks of once-daily PPI · "not asthma" on normal spirometry alone. Review at the end of each full trial, recording drug, dose, duration, adherence, technique and response before moving on, with the triggers written down: stridor, massive haemoptysis, breathlessness at rest or SpO₂ below 92% → 999; new haemoptysis, weight loss, fever with night sweats, or hoarseness beyond 3 weeks → same-day or NG12 route. Name who reviews the CXR. Do not: omit the chest X-ray · label "smoker's cough" or COPD without imaging and spirometry · start the triad before excluding cancer and TB · give antibiotics without a defined infective indication, or a codeine suppressant as a substitute for diagnosis · stop a trial early and call it a failure · or attribute a cough in an immunosuppressed patient to the triad.
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Endpoint and documentation Finish with one of four conclusions

1 · Emergency

999 route taken; the concern, onset, SpO₂, observations, airway findings, what was given and when.

2 · Urgent or same-day

Same-day, TB or NG12 route taken with date; the question being excluded; CXR and sputum sent.

3 · Treatable cause, managed

CXR recorded; ACE inhibitor stopped; the named cause and trial with drug, dose and full duration, technique checked, review date and thresholds written down.

4 · Unexplained after trials

Each trial listed with drug, dose and duration; uncertainty stated; §6 referral sent with the CXR and trial history.
Why primary-care management is safe today, in one line: no row on the page-1 screen applies · no haemoptysis, weight loss, fever with night sweats, stridor or hoarseness · SpO₂ normal at rest and on exertion · a chest X-ray has been done and is normal · any ACE inhibitor stopped · pack-years, asbestos and TB risk recorded · NG12 criteria documented as absent · one triad diagnosis named and treated for its full trial length · review booked at the end of that trial with a named reviewer and written thresholds. Safety-net: contact us the same day for coughed-up blood, weight loss, fevers or night sweats, breathlessness at rest, or hoarseness beyond 3 weeks; 999 for noisy or difficult breathing, or a large amount of blood. Remote assessment limitation. Convert to face-to-face where the cough is productive or bloody, there is breathlessness, weight loss, fever or night sweats, hoarseness or dysphagia, SpO₂ cannot be measured, the chest cannot be examined, or the patient is immunosuppressed or at TB risk — and a chronic cough cannot be signed off remotely until the chest X-ray has been seen.
Clinical decision support only; follow local respiratory, TB-notification and prescribing policies and check doses against the current BNF. Source hierarchy: NICE guidelines and CKS first, then BNF/MHRA for doses and safety, then national specialty guidance. Sources: NICE NG12 Suspected cancer (May 2025) · NG245 Asthma · NG115 COPD · NG106 Chronic heart failure · NG117 Tuberculosis · CG184 Gastro-oesophageal reflux disease and dyspepsia · NG120 Cough (acute) antimicrobial prescribing · NICE CKS Cough, Chronic cough, Asthma, Rhinitis · British Thoracic Society guideline on cough · European Respiratory Society guidelines on chronic cough · BNF · MHRA. Review after any guidance or medicines-safety update, otherwise every 6 months. © Reasoning GP · gpreasoning.uk