Private chronic cough clinic in London, same-day respiratory.

The three commonest causes

• Upper airway cough syndrome — post-nasal drip from rhinitis or sinusitis. A sensation of mucus at the back of the throat, frequent throat clearing, worse on lying down. Treated with a steroid nasal spray used correctly and saline rinsing.
• Asthma and cough-variant asthma — cough may be the only symptom, with no wheeze at all. Typically worse at night, in cold air, with exercise or with allergens. Responds to inhaled steroid.
• Reflux — acid or non-acid reflux irritating the throat, often without any heartburn. Worse lying flat, after meals, and on talking. Treated with acid suppression and lifestyle change over several weeks.

These three account for the majority of chronic cough in non-smokers with a normal chest X-ray. More than one is frequently present at the same time, which is why treating only one gives partial improvement.

Other causes worth considering

• Smoking, and COPD or bronchiectasis
• Whooping cough — the hundred-day cough, now circulating again in adults
• Tuberculosis, particularly with weight loss, night sweats or relevant travel or contact history
• Heart failure, causing cough and breathlessness worse on lying flat
• Occupational and environmental exposure — dust, fumes, mould, damp housing
• Chronic cough hypersensitivity — a sensitised cough reflex triggered by talking, laughing, cold air or perfume, often after a viral illness

What investigation involves

• A careful history — timing, triggers, sputum, medication, occupation and travel — which identifies the cause more often than any test
• Chest X-ray for any cough persisting beyond three weeks
• Spirometry, and tests of airway reactivity where asthma is suspected
• Blood tests, including inflammatory markers and, where indicated, TB testing
• Trials of treatment, each given an adequate period before being judged — typically four to eight weeks
• ENT assessment or CT where the picture is not straightforward

Self-help while the cause is treated

• Stop smoking and avoid smoky, dusty environments.
• Honey and lemon in warm water is as effective as most cough medicines, and cheaper. Never honey under one year old.
• Sip water frequently; a dry throat perpetuates the cough reflex.
• Raise the head of the bed if reflux or post-nasal drip is likely.
• Cough suppressants have weak evidence and are not recommended for children under six.