Chronic Cough

Do you have a cough that is persistent and irritating?

Coughing is a natural reflex to clear the irritants for the airways and the lungs. However if a cough lasts for >8 weeks, you are suffering from chronic cough.

It can affect your sleep, interfere with your work and social life. You may be anxious and worried too. Occasionally you may have chest pain, giddiness and tiredness as a result of the chronic cough.

It is a common symptom and there are various causes of chronic cough. Some of the causes can be serious and life-threatening and therefore, it is important to see a doctor for further evaluation.

• Common causes of chronic cough
• Tests and Diagnosis

Common conditions that can cause chronic cough include:

• Asthma

It is the common cause of chronic coughing in the population. It may present with wheezing, chest tightness and shortness of breath. In cough-variant asthma coughing is the only symptom.

Upon contact with certain chemicals or cold air, the cough may become worse and this is referred to as hyperactive airways disease. Inhaled steroids are effective in reducing the inflammation in the airway and improving the cough. Inhaled bronchodilators like salbutamol may also prescribed.

• Postnasal drip

Excess mucus produced from an allergy reaction, common cold or a sinus infection, can accumulate at the back of the throat. This can cause irritation and inflammation that result in persistent coughing and need to clear the throat. Antihistamine, decongestant and nasal steroid spray are commonly prescribed.

• Gastro-Esophageal Reflux Disease (GERD)

Symptoms associated with GERD include frequent heartburn or a sour taste in the mouth, but half of the patients do not always present with these symptoms. Blood pressure medications Angiotensin-converting enzyme (ACE) inhibitors used to treat hypertension are known to cause chronic cough (up to 20%). The cough usually begins within hours of the first dose to months after the initiation of therapy. Once the drug is ceased, the cough will subside within 1-4 weeks.

The constant irritation from the acid reflux in the esophagus, throat and even in the lungs can lead to chronic coughing. Medications given will be mainly to reduce acid production in the stomach. Patient will be advised not to eat 2-3 hours before bedtime and avoid certain foods that can worsen the cough.

• Blood pressure medications

Angiotensin-converting enzyme (ACE) inhibitors used to treat hypertension are known to cause chronic cough (up to 20%). The cough usually begins within hours of the first dose to months after the initiation of therapy. Once the drug is ceased, the cough

• Chronic Bronchitis

Chronic productive cough is one of the symptoms of chronic bronchitis. The inflammation of the bronchial airways causes congestion, breathlessness and wheezing of the lungs. It is not uncommon in current or ex-smokers as a result of long term cigarette smoking. Known as chronic obstructive pulmonary disease – COPD, a spirometry- simple lung function test, is useful to confirm the diagnosis. Treatment will include smoking cessation and use of bronchodilator inhalers.

Other causes of chronic cough include lung cancer, pulmonary tuberculosis, bronchiectasis and chronic lung infection or inflammation.

Tests and Diagnosis
The initial step in the evaluation is a medical history and physical examination by a respiratory physician.

• Lung imaging

Chest x-ray is useful to check for lung cancer, pulmonary tuberculosis, lung scarring and other abnormal lung structures A more detailed imaging test as CT scan provide more detailed views of the lungs and it may be requested if the chest x-ray showed abnormalities.

• Lung function tests

These simple, noninvasive tests evaluate how the lung is functioning. It is useful in diagnosing asthma, COPD and restrictive lung diseases. There are 3 components to pulmonary function testing: spirometry, lung volumes and diffusion capacity.


1. Spirometry is the most basic test. Spirometry measures how much air you can quickly breathe into and out from your lungs. This test is done by having you take a deep breath and blow hard into a tube connected to a machine. Most patients can perform this test easily in the outpatient setting with coaching from a trained technician. Sometimes a methacholine challenge test is done to check for hypersensitivity of the airway. Spirometry is useful to diagnose COPD and asthma.

2. Lung volumes measures how much air your lungs can hold, and there are two ways for the measurement to be done- the nitrogen washout technique and the body plethysmography technique. Lung volumes are useful to diagnose restrictive lung diseasees like pulmonary fibrosis.

3. Diffusion capacity measures how well your lungs put oxygen into and remove carbon dioxide from your blood. It involves breathing in a very small amount of carbon monoxide and measuring the amount that is transferred from the alveoli to the capillary. This test is useful to follow up lung fibrosis and scarring.

Exhaled nitric oxide
This is a simple non invasive test that takes 5 minutes. Nitric oxide content is measured from a patient’s exhalation breath. When exhaled nitric oxide is raised, there is likely an eosinophilic inflammation in the airways that can occur in asthma and eosinophilic bronchitis.

Bronchoscopy
Bronchoscopy is a technique of visualizing the inside of the airways, inserting a small scope into the airways. This allows the doctor to check the patient’s airways for bleeding, tumors, infection or inflammation. This test is commonly done in the endoscopy room. Specimens may be taken from inside the airways or lungs.

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