What is asthma?

Breathing comes naturally to all of us, but for individuals with asthma, breathing may sometimes be difficult and laborious. When you breathe, air goes in either through your nose or mouth. The air then makes its way down to your throat and eventually your lungs. Within your lungs are small airways known as bronchioles and alveoli. Once air reaches the alveoli, it is transferred to your blood which then disseminates it all over the body. However, when someone has asthma, this intricate process is disrupted.

Asthma is a chronic medical condition that results in the inflammation and swelling of the lower respiratory tract in your lungs1. It affects approximately 5% of adults and 20% of children in Singapore2. In asthma, your respiratory airways become narrow and swells, this leads to an increase in mucus production which then makes breathing difficult and induces coughing. Individuals with asthma may also start wheezing when they breath and experience shortness of breath3.

Asthma is either a minor inconvenience or a life-threatening medical condition. It affects both adults and children, and studies have shown that as many as 70% of individuals with asthma remain undiagnosed4.

Illustration of a lung with Asthma

What are the causes of asthma?

The main causes of asthma are still unknown, however, there are several triggers that may induce an asthma attack in some individuals, these are:

  • Pets: reducing exposure to pet dander can reduce the incidence of asthma attacks5.
  • Pollution: air pollution from cars, factories, haze are some triggers that can cause an asthma attack6.
  • Exercise: strenuous exercise may trigger asthma attacks in some individuals7.
  • Dust mites: have been shown to trigger mild to severe asthma attacks8.
  • Mold: studies have shown that household mold is associated with childhood asthma9.
  • Occupational hazards: individuals occupationally exposed to certain factors have a high risk of asthma10.
  • Smoke: exposure to tobacco smoke, whether firsthand or second hand, triggers asthma attacks11.

Whatever the trigger of asthma, it is often the over-reaction of the immune system that results in the undesirable effects of an asthma attack. Avoiding the trigger of your asthma can reduce its incidence.

What are the symptoms of asthma?

Asthma occurs when the airways tighten, narrow, inflame, and fill with mucus. There are three main signs of asthma, these are12:

  • Blocked airways: tightened airways make it difficult for air to pass through.
  • Inflamed airways: airways can become inflamed and swollen causing permanent damage to your lungs.
  • Irritated airways: over sensitive and over reactive airway and immune response to mild triggers.

Once your airways become triggered, you will experience one or more of the following symptoms13:

  • Coughing: more common at night or in the morning (when the air is cooler).
  • Wheezing: whistling sound when you breathe.
  • Shortness of breath: narrowed airways make it difficult for adequate air to pass through.
  • Chest tightness: tightened airways will make your chest feel tight and constricted.

Asthma is classified into 4 categories:

ClassificationIncidence of symptoms
Mild IntermittentSymptoms up to two days a week and up to two nights a month
Mild persistentSymptoms more than twice a week but not more than once in a single day
Moderate persistentSymptoms once a day and more than one night a week
Severe persistentSymptoms throughout the day on most days and frequently at night

Table from3: 

If you experience one or more of these symptoms, it is imperative that you make an appointment with a respiratory specialist. Managing chronic asthma is key to lower morbidity.

Is asthma painful?

Sometimes, some individuals might experience chest pains.

Who is at risk of asthma in Singapore?

While the main causes of asthma are unknown, there are various factors that increase your risk of asthma, these are14:

  • Allergies: you are more prone to asthma if you have allergies.
  • Genetics: if asthma runs in your family, you are more susceptible to developing it.
  • Infections: certain respiratory infections (e.g., respiratory syncytial virus or RSV) can cause damage to lungs and increase risk of asthma.
  • Environmental factors: sometimes exposure to certain environmental factors such as pollution, fumes, toxins, etc. can increase your risk of asthma, this is particularly true for young children

How is asthma diagnosed?

If your respiratory specialist (or pulmonologist) suspects that you have asthma based on your medical history and physical examination, the following diagnostic tests will be conducted for a more accurate diagnosis15:

  • Spirometry: checks how much air you can exhale and how fast you can exhale after a deep breath. This helps to identify if your airways are narrowed or restricted.
  • Peak flow testing: measures how quickly you can exhale. Lower peak flow readings are signs that your lungs may not be working as well as they should.
  • Bronchoprovocation testing: also known as the methacholine challenge, used to test how reactive your lungs are to certain triggers.
  • X-rays: chest x-rays may be used to check if there are other issues causing your symptoms.
  • Blood tests: may be used to check for possible infections.

What are the treatment options for asthma in Singapore?

Asthma is a chronic respiratory condition and there is no cure. The main goal for asthma treatment is maintaining good control by reducing or minimising exposure to triggers. Continuous management and monitoring by your respiratory specialist are important. In addition to reducing or minimising exposure to triggers, asthma can be treated with the following medications3:

  • Bronchodilators: help to relax the muscles around your airways, thereby preventing airway constriction.
  • Anti-inflammatory medications: help to reduce inflammation, swelling, and mucus production.
  • Anti-cholinergics: helps prevent your airway muscles from tightening
  • Biologics: these target specific antibodies in your body to prevent asthma-causing inflammation.

Treatment of asthma depends on the type of asthma you have.

Frequently asked questions

Can asthma be cured?

No, asthma is not curable, but it can be managed.


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  2. John, L. L. (2020, May 19). Does Asthma Increase the Risk of Other Respiratory Diseases? Retrieved from health plus:
  3. Mayo Clinic Staff. (2022, March 5). Asthma. Retrieved from Mayo Clinic:
  4. Shawn D Aaron, L. P. (2018). Underdiagnosis and Overdiagnosis of Asthma. American Journal of Respiratory and Critical Care Management, 1012-1020.
  5. Peter J Gergen, H. E. (2017). Sensitization and exposure to pets: The effect on asthma morbidity in the United States population. The Journal of Allergy and Clinical Immunology.
  6. Michael Guarnieri, J. R. (2014). Outdoor air pollution and asthma. Lancet, 1581-1592.
  7. Mayo Clinic Staff. (2020, December 16). Exercise-induced Asthma. Retrieved from Mayo Clinic:
  8. American Lung Association. (2022, August 23). Dust Mites. Retrieved from American Lung Association:
  9. Siyuan Xiao, A. L. (2021). Household mold, pesticide use, and childhood asthma: A nationwide study in the U.S. International Journal of Hygiene and and Environmental Health.
  10. Alicia Armentia, M. L. (2004). Occupational asthma due to grain pests Eurygaster and Ephestia. The Journal of Asthma, 99-107.
  11. Megan Stapleton, A. H.-T. (2011). Smoking and asthma. Journal of the American Board of Family Medicine, 313-322.
  12. WebMD Editorial Contributors. (2021, May 15). Asthma. Retrieved from WebMD:
  13. Nurcicek Padem, C. S. (2019). Classification of asthma. Allergy and Asthma Proceedings, 385-388.
  14. Cleveland Clinic Medical Professional. (2022, January 19). Asthma. Retrieved from Cleveland Clinic:
  15. Tianshi David Wu, E. P. (2019). Asthma in the Primary Care Setting. Medical Clinics of North America, 435-452.
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