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Symptom sorter – cough in adults

The GP overview

This is a symptom that patients seem to fear or value – as a signifier of possible cancer or a justifier of antibiotics – far more than GPs. Most coughs are simply viral URTIs, but the GP should be aware of the various other possibilities, especially when the symptom is persistent.

Differential diagnosis


  • URTI.
  • LRTI.
  • Asthma.
  • COPD.
  • ACE inhibitor side-effect.


  • Smoking (including passive smoking).
  • Lung tumour (primary or secondary).
  • Rhinitis.
  • GORD.
  • Left ventricular failure.
  • Bronchiectasis.
  • Aspiration (for example, post stroke).


  • Tuberculosis.
  • Other medication side-effect (such as methotrexate).
  • Pulmonary fibrosis.
  • Fibrosing alveolitis.
  • Extrinsic allergic alveolitis.
  • Psychogenic.
  • Laryngeal carcinoma.
  • Inhaled foreign body.
  • Diaphragmatic irritation (for example, abscess).

Ready reckoner

  URTI LRTI Asthma COPD ACE inhibitor side-effect
Associated shortness of breath No Possible Possible Yes No
Productive cough Possible Yes Possible Yes No
Persistent or recurrent cough No No Yes Yes Yes
Audible wheeze No Possible Possible Possible No
On ACE inhibitor Possible Possible Possible Possible Yes

Possible investigations




FBC, ESR/CRP, spirometry, PEFR

Small print

  • Sputum, cardiac investigations, serum precipitins, hospital-based investigations such as CT scan and bronchoscopy.
  • FBC – haemoglobin may be reduced in malignancy and chronic illness, WCC raised in infections, eosinophils raised in allergic conditions.
  • ESR/CRP – raised in neoplasia, infective and inflammatory conditions.
  • Chest X-ray – may show signs in a variety of the relevant differentials, such as LRTI, tumour and TB.
  • Spirometry – may show characteristic patterns particularly in asthma, COPD and pulmonary fibrosis.
  • Serial peak flow – may be helpful in diagnosis of asthma.
  • Sputum – may be useful in diagnosing TB and occasionally helps guide antibiotic treatment in LRTI or exacerbation of COPD.
  • Cardiac investigations, such as BNP or echocardiogram if LVF suspected.
  • Serum precipitins in suspected extrinsic allergic alveolitis.
  • Hospital-based investigations – further investigations such as CT scan or bronchoscopy may be required to clarify CXR abnormalities or pursue clinical suspicion.

Top tips

  • Explain to patients that it is not unusual for the cough of a simple URTI to go on for three weeks – this will reduce unnecessary re-attendances.
  • Take a careful history of provoking factors in the case of persistent cough – this is more likely to reveal the diagnosis than is chest auscultation.
  • Have a low threshold for arranging a chest X-ray in the middle-aged and elderly smoker with a cough.
  • ACE inhibitor-associated cough may come on many months – or even longer – after initiating treatment. It starts to improve within one to four weeks of stopping treatment, but may take three months to settle completely.
  • In a persistent cough with a normal CXR and no chest signs, think asthma, GORD and rhinitis – a therapeutic trial for each may be needed to clinch the diagnosis.

Red flags

  • Remember to ask about foreign travel. Atypical pneumonias are infrequent, and TB rare, but both can still present.
  • Beware of persistent cough, weight loss and voice change in a smoker – arrange an X-ray to exclude malignancy.
  • Night sweats with persistent cough suggest significant pathology such as TB or malignancy.
  • Beware the patient on immunosuppressants: these drugs may alter the clinical picture, predispose to serious complications and in some cases (e.g. methotrexate) may be the cause of the cough itself.

Dr Keith Hopcroft is a GP in Laindon, Essex.

Dr Vincent Forte is a GP in Gorleston, Norfolk.

The fifth edition of Symptom Sorter is available from Radcliffe Publishing for £34.99.

Symptom Sorter 5th edition


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