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Asthma and Smoking

What is Asthma?

Asthma is a chronic lung disease that causes episodes of difficulty in breathing.

Asthma symptoms are caused primarily by chronic inflammation of the airways. This makes the airways of the patient with asthma highly sensitive to various trigger factors.

When the airways inflammation is triggered by any type of external or internal trigger factors, the airways swell and fill with mucus.

Muscles within the airways will contract which can lead to further narrowing of the airways. The airways narrowing makes it difficult for the air to be breathed in and out from the lungs and it lead to various symptoms of asthma.

How is Smoking Related to Asthma?

Tobacco smoke is a powerful trigger of asthma symptoms. If the patient has asthma, an asthmatic attack can happen if something irritates the airways and triggers an attack.

Tobacco smoke including secondhand smoke, is one of the most common asthma triggers. Secondhand smoke is the combination of smoke from a burning cigarette and smoke exhaled by a smoker.

How Does Tobacco Smoke Trigger Asthma?

Tobacco smoke (and chemicals in cigarette smoke) has four main effects on the airways:

  1. When a person inhales tobacco smoke, irritating substances deposit in the lining of the airways and can cause an attack in a person who has asthma.
  2. Tobacco smoke also damages the tiny hair-like structures in the airways (cilia), so that they are unable to work and allowing the dust and mucus to accumulate in the airways.
  3. Smoke also causes the lungs to make more mucus than normal and trigger an asthma attack
  4. Smoke can damage the airways by destroying the lung tissue and make the airways less elastic and narrower by causing more inflammation in the airways

What are the Effect of Tobacco Smoking on Patient with Asthma?

As tobacco smoke is a powerful trigger of asthma symptoms, it can trigger an asthma attack and further worsen the asthma symptoms.

  • Patient with asthma who smoke will have more frequent asthmatic attacks
  • They will have more severe asthmatic attack, and are more likely to be admitted to hospital
  • They might need to use higher doses of preventer medication to control their asthma

Is Secondhand Smoke harmful to a Person with Asthma?

Tobacco smoke is a powerful trigger of asthma symptoms. Exposing to secondhand smoke/ passive smoke/ environmental tobacco smoke, may be more harmful than actual smoking.

This is because the smoke that burns off the end of a cigarette contains much more harmful substances (such as tar, carbon monoxide, nicotine and others) than the smoke inhaled by the smoker.

Secondhand smoke is especially harmful to people who already have asthma.

  • When a person with asthma is exposed to secondhand smoke, he/ she is likely to experience more frequent asthma symptoms such as wheezing, coughing and shortness of breath associated with asthma.
  • Children with asthma who are exposed to secondhand smoke are more likely to have poorer asthma control and more likely to be admitted for severe asthma attack
  • Children of parents who smoke are also more likely to develop lung and sinus infections and these can worsen the asthma symptoms and control.

What is the Effect of Smoking on Asthma During Pregnancy?

  • If a woman smokes when she is pregnant, the chemicals in the  smoke will be passed to the developing baby through the umbilical cord and this will increase the baby’s risk of developing wheezing symptoms early in life.
  • Smoking during pregnancy also causes many other problems, such as low-birth weight babies, premature births and increases the risk of fetal death and stillbirth.

Is Secondhand Smoke Harmful to Non-asthmatic Children?

Children are more susceptible than adults to the effects of secondhand smoke because their lungs are still developing.

  • Children of mothers who smoked during pregnancy are more likely to have lung problems and are ten times more likely to develop asthma.
  • Young child who is exposed to smoke is at a much higher risk of developing asthma-like symptoms in early childhood.
  • Children who inhale secondhand smoke are also at increased risk for a variety of problems including ear infections, bronchitis, pneumonia, allergic diseases.

Even if the parents go outdoor to smoke, particles can still be present on them when you return indoors, so although it is better than smoking nearby their children, it still might have long term affect on them.

What other health issues are related to smoking?

People who smoke can develop many other health issues such as permanent lung disease (Chronic Obstructive Airways Disease), stroke, heart disease, high blood pressure, lung cancer and many more.

In summary

Tobacco smoke is a powerful asthma trigger that can worsen asthma symptoms. People who smoke and who have asthma will have worse asthma control, more airway damage and faster loss of lung function. Second-hand smoke or passive smoking, is also a trigger for people with asthma. Therefore, it is important for asthma patient to quit smoking or to avoid exposure to secondhand smoke to prevent further attack of severe asthma.


  1. Asthma Foundation. Smoking and asthma. [accessed 2014 August 28]
  2. American Academy of Allergy, Asthma & Immunology: No Butts About It: Smoking Makes Asthma Worse. Updated May 15, 2013 Worse.” [accessed 2014 August 28]
  3. British Thoracic Society. British Guideline on the Management of Asthma-a national guideline 2008.
  4. Centers for Disease Control and Prevention. Asthma: Common Asthma Triggers [last updated 2012 Aug 20; accessed 2014 August 28].
  5. Centers for Disease Control and Prevention. Secondhand smoke and asthma. [accessed 2014 August 28].
  6. Global Strategy for Asthma Management and Prevention: Global Initiative for Asthma (GINA) (Updated 2014)
  7. Ministry Of Health Malaysia. Clinical Practice Guidelines For Management Of Adult Asthma 2002.
Last Reviewed : 5 March 2016
Writer : Dr. Ho Bee Kiau
Accreditor : Dr. Norhaya bt. Mohd Razali

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