Chronic Cough

What is Chronic Cough?

Coughing is something we all do from time to time, whether it’s a tickle in our throats or just a habitual way to clear our throats. It is one of our body’s defense mechanisms to help remove mucus and foreign particles from the respiratory tract. Coughing is usually one of the first signs of illness such as the common cold, flu, or COVID-19. But if a cough lasts longer than a week or two, you may start feeling concerned. It may mean that your mild respiratory illness has progressed to something a little more serious like bronchitis or maybe you have developed a new allergy. 

When your cough persists for longer than a few weeks, that’s where the possibility of a chronic or prolonged cough comes in. Adults with a cough that lasts longer than 8 weeks and children with a cough that lasts longer than 4 weeks, are usually diagnosed with a chronic cough¹. It is a very common condition and is one of the most common reasons for referral to a respiratory specialist². An estimated 2-18% of the world’s population are afflicted with a long-lasting or chronic cough³ and they can range from a mild annoyance to affecting the quality of life.

What are the common causes?

There are various causes of chronic cough which can range from benign to severe, they may be caused by one or a combination of factors.

Common causes of chronic cough:

• Smoking: lifelong smokers often experience chronic cough⁴.
• Asthma: one of the most common causes of chronic cough⁵.
• Post-nasal drip: another common causecommonly known as upper airway cough syndrome, occurs when mucus drips down the back of the throat, tickling it and resulting in a cough^4,5.
• Acid reflux: 3^rd most common cause, occurs when stomach acid flows back up the throat which results in throat irritation and chronic coughing^4,5. 
• Infections: pneumonia and bronchitis, long-term inflammation of the lungs^4,5.
• Chronic obstructive pulmonary disease (COPD): chronic lung inflammation that causes airway obstruction^4,5.
• Blood pressure medication: angiotensin-converting enzyme (ACE) inhibitors are known to cause chronic cough in some people⁵.  

Less common causes of chronic cough:

• Bronchiectasis: damaged airway walls that lead to inflamed and thickened airways^4,5. 
• Cystic fibrosis: excess mucus in the lungs and airways6 (Mayo Clinic Staff, 2019).
• Bronchiolitis: inflammation of the bronchioles⁶.
• Lung cancer: abnormal cell growth in the bronchi, bronchioles, or alveoli⁶.
• Sarcoidosis: type of disease that causes clumps of inflammatory cells form in multiple organs such as the lungs and lymph nodes⁶.
• Idiopathic pulmonary fibrosis: scarring of the lungs with no known cause⁶.

What are the symptoms of Chronic Cough?

An obvious symptom of a chronic cough is a cough. However, there are other additional symptoms that may accompany a chronic cough, these are:

• Runny or stuffy nose
• Heartburn or acid reflux with sour taste in the mouth
• Sore throat
• Frequent throat clearing
• Hoarseness
• Wheezing and breathlessness
• Feeling of liquid dripping down the back of the throat
• Headaches
• Chest discomfort
• Night sweats
• Coughing up blood

Is Chronic Cough painful?

Most of the time chronic cough is not painful. However, some individuals with chronic cough experience chest pains from the exertion of coughing.

Who is at risk of Chronic Cough in Singapore?

Like all respiratory diseases, the number one risk factor for chronic cough is smoking. Other risk factors include:

• Exposure to second-hand smoke and smoking increases your risk to COPD and other respiratory conditions which can then lead to chronic cough.
• Weak immune system which leads to increased chances of infections including respiratory infections which can then lead to chronic cough.

How is Chronic Cough diagnosed in Singapore?

If your respiratory specialist suspects a chronic cough after studying your medical history and conducting a physical examination, the following diagnostic tests may be conducted:

• X-ray: a chest x-ray can check for lung cancer and a throat x-ray can check for any recent sinus infections.
• Computed tomography scans (CT-scans): like an x-ray but with more accurate views, it may also be used to check for signs of lung cancer or infections.
• Lung function tests: spirometry or peak flow readings can be used to check on how well your lungs are functioning.
• Sputum test: mucus from deep within your lungs will be tested for signs of infections such as tuberculosis (TB). 
• Bronchoscopy: a long, thin tube with a light and camera attached at one end will be inserted into your throat and gently guided down to your lungs.
• Rhinoscopy: a long, thin tube with a light and camera attached at one end will be inserted into your nose to check on your nasal passages and sinuses.

What are the treatment options for Chronic Cough in Singapore?

The treatment for chronic cough depends on the underlying cause. Treatment options include:

• Quit smoking
• Switch ACE-inhibitors
• Medications: antihistamines, decongestants, corticosteroids for the treatment of allergies and post-nasal drip.
• Asthma medications: bronchodilators and corticosteroids reduce inflammation and open up the airways.
• Antibiotics: to treat bacterial infections that may be causing your chronic cough.
• Antacids: for treatment of acid reflux.

Frequently asked questions

References

1. Miles Weinberger, M. H. (2020). Diagnosis and management of chronic cough: similarities and differences between children and adults. F1000 Research.
2. Vijo Poulose, P. Y. (2016). Approaching chronic cough. Singapore Medical Journal, 60-63.
3. Alyn Morice, P. D. (2021). Chronic cough: new insights and future prospects. European Respiratory Review.
4. Kian Fan Chung, I. D. (2008). Prevalence, pathogenesis, and causes of chronic cough. Lancet, 1364-1374.
5. Weinberger, S. E. (2022, October 19). Patient education: Chronic cough in adults (Beyond the Basics). Retrieved from UpToDate: https://www.uptodate.com/contents/chronic-cough-in-adults-beyond-the-basics
6. Mayo Clinic Staff. (2019, July 9). Chronic cough. Retrieved from Mayo Clinic: https://www.mayoclinic.org/diseases-conditions/chronic-cough/symptoms-causes/syc-20351575