Persistent cough

What can cause a persistent cough?

Cough protects the airways, but a cough lasting more than eight weeks is called chronic cough in adults. Causes and contributing factors include airway inflammation, smoking, infection, nasal disease and some medicines. An overly sensitive cough reflex can also be important. More than one factor may be involved.

How is it assessed?

Your clinician asks about duration, sputum, triggers, medicines, smoking, nasal symptoms and reflux. Initial investigations for chronic cough generally include a chest X-ray, full blood count and spirometry or full lung function tests, with FeNO where available.

CT scans and bronchoscopy are selected for a specific clinical reason rather than used routinely for every cough. Persistent productive cough, for example, may need investigation for bronchiectasis. A normal chest X-ray does not remove the need for reassessment when symptoms persist or concerning features develop.

How is it treated?

Treatment targets identified causes. Inhalers, antibiotics and acid-suppressing medicines are not suitable for every cough. A productive cough may need airway-clearance support.

We refer to specialist speech and language therapists, usually at the hospital where you are seen, for cough-control therapy. This may include techniques to manage the urge to cough, breathing strategies and voice or throat care.

Refractory chronic cough and unexplained chronic cough

Some people continue to cough despite thorough assessment. Two related diagnoses describe this:

• Refractory chronic cough – cough that persists even though conditions linked to it have been identified and treated appropriately.
• Unexplained chronic cough – cough for which no underlying cause is found after thorough investigation.

Both are now understood as a cough hypersensitivity problem: the nerves that trigger coughing become over-sensitive. A tickle or irritation in the throat, and coughing set off by talking, laughing, cold air, perfumes or eating, are typical.

These are diagnoses of exclusion. They are made only after other causes have been looked for and treated where present, including asthma and eosinophilic airway inflammation, reflux (GORD), nose and sinus disease, interstitial lung disease, bronchiectasis and other airway disease, smoking, and medicines such as ACE inhibitors. A normal chest X-ray alone is not enough to make the diagnosis.

Medicines for refractory or unexplained chronic cough

Medicines that act on cough-reflex sensitivity may be discussed for selected adults whose chronic cough persists despite assessment and treatment of identified causes. Benefits and side effects vary. Suitability, costs and follow-up are discussed in clinic before any treatment is prescribed.

Prepare for your consultation

Bring a medication list, previous results and a note of when the cough occurs. Tell us about coughing blood, weight loss, swallowing problems or episodes of fainting.

Sources and further information

• BTS Clinical Statement on Chronic Cough in Adults
• ERS chronic cough patient guide
• NHS: Cough

This guide gives general information for adults and does not replace individual medical advice.