What is 'chronic cough'?
The medical definition of a chronic cough is one that continues for eight weeks (or in children, for four weeks). Although coughing itself is a natural body function which allows particles and mucus to be cleared from the lungs and airways (to prevent infection), a continuous cough can create other issues (eg headache, muscle strain, dizziness) and may be the sign of an underlying condition, so you should always have a chronic cough checked by your doctor.
What causes chronic cough?
The vast majority (90%) of cases of chronic cough are caused by three things...
Asthma is the main cause of chronic cough in children, and second in adults, after postnasal drip. A cough related to asthma may be brought on by exposure to cold (or hot) air or certain smells or fumes. There is a type of asthma known as 'cough variant asthma' where a cough is the only symptom.
This is where secretions from the nose literally 'drip' into the back of the throat, causing irritation and a cough to clear the throat. This can happen even where there are no other symptoms, in which case it is called 'silent' postnasal drip. This is the most common cause of chronic cough in adults.
Reflux (or GERD - Gastroesophageal reflux disease)
This is where stomach acid flows the wrong way back up into the gullet (the oesophagus). Although normally accompanied by other symptoms such as heartburn and a strange taste in the mouth, a continuing cough can occasionally be the only symptom.
Other causes may include...
- Respiratory Tract Infections - including eg bacterial tracheobronchitis, bacterial sinusitis or pertussis (whooping cough). Postnasal drip can bring some of these infections on
- Some medications - particularly ACE inhibitors used to treat high blood pressure
- Chronic Bronchitis - affects mainly smokers (Technically emphysema and chronic bronchitis fall under COPD, they are in fact very different pathologies)
- Non-Asthamtic Eosinophilic Bronchitis - a form of inflammation of the airways
- Aspiration - the inhalation of a foreign object or food 'going down the wrong way'
- Bronchiectasis - damage to the airways
- Cystic Fibrosis
- Lung Cancer
- Sarcoidosis - inflammation of cells in the body, although commonly affecting the lungs
How is the cause of chronic cough diagnosed?
A number of tests, after a physical examination and review of your medical history, may be recommended...
- Chest x-ray
- CT (Computerised Tomography) scan
- Lung function tests
- Pathology (testing a sample of mucus)
- Rhinoscopy - a special endoscopy (using a thin tube with a light and camera on the end) for the nose
- Spirometry - helps determine the cause of chronic coughs in children
How is chronic cough treated?
This depends on what is causing the cough. Common treatments include...
- Medication to treat allergies/postnasal drip (eg antihistamines, decongestants)
- Asthma medications
- Antibiotics to treat bacterial infections
- Acid blocking medication - for sufferers of GERD
- Cough suppressant medications
Children under 4 should not take over the counter cough/cold medicine without consulting your doctor, as they can be harmful to young children.