Persistent Cough
How long a cough should last, what a three-week cough warrants, and which features need urgent assessment.
Last revised
Most coughs follow a viral infection and settle within three weeks, though a post-viral cough can linger for up to eight. A cough lasting more than three weeks without an obvious cause should be assessed.
The three-week rule
A cough persisting beyond three weeks is the threshold at which UK guidance advises seeing a GP, and in smokers or people over 40 it is one of the recognised prompts to consider a chest X-ray. The reason is straightforward: it is the commonest presenting symptom of lung cancer, and stage at diagnosis dominates outcome.
Common causes of a long cough
Post-infectious airway irritation, which can take six to eight weeks to settle. Asthma, particularly if the cough is worse at night or with exercise. Reflux, often with a sensation of acid or a cough when lying flat. Post-nasal drip. ACE inhibitor medicines, which cause a characteristic dry cough in a minority and resolve on switching. Smoking itself.
Dry versus productive
A dry cough points more towards irritation, asthma, reflux or medication. A productive cough with discoloured sputum most often follows infection, but daily sputum production over months suggests chronic bronchitis or bronchiectasis and warrants investigation. Coughing up blood, in any quantity, always needs assessment.
Children
Children get frequent coughs, and a cough lasting a couple of weeks after a cold is normal. Assessment is needed for a cough with noisy breathing or wheeze, a barking cough with difficulty breathing, coughing that began suddenly with possible inhalation of a small object, or any cough in a child who is not feeding or is unusually drowsy.
At a glance
| Term | Detail |
|---|---|
| Typical viral cough | settles within 3 weeks |
| Post-viral cough | can persist 6-8 weeks |
| Threshold to see a GP | more than 3 weeks |
| Common medicine cause | ACE inhibitors, causing a dry cough |
| Always needs assessment | coughing up blood, in any amount |
| Additional prompt for chest X-ray | smoker or over 40 with a persistent cough |
When to get help
See a GP for a cough lasting more than three weeks, or sooner if you cough up blood, lose weight without trying, have night sweats, chest pain, hoarseness lasting three weeks, or increasing breathlessness. Call 999 for severe difficulty breathing, blue lips, confusion, or a child who is struggling to breathe, grunting, floppy or will not wake.
Where to go next
Where this comes from
- NICE - Suspected cancer: recognition and referral
- NHS - Cough
- Asthma + Lung UK - persistent cough
Medical disclaimer
This article is general information, not medical advice. It cannot account for your own history, medication or circumstances. Always speak to a GP, pharmacist or another qualified health professional before making changes that affect your treatment, and never delay seeking medical advice because of something you have read here. In an emergency, call 999.
