Asthma Physiology: What Happens in the Lungs During an Attack

What asthma does to the airways of your lungs

Young man using inhaler
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The immune system and immune response are at the heart of the symptoms that develop in asthma. In asthma, the muscles lining the airways are very sensitive and overreact to substances or events, known as triggers, that other people tolerate without a problem.

Your asthma symptoms are caused by 3 main physiological processes, and treatment is targeted to address all of them:

  • Tightening of the muscles lining the airways: This contraction or tightening of the bronchial smooth muscles is called bronchospasm or bronchoconstriction. As these muscles tighten around the outside of your bronchial tubes, causing narrowing, it becomes more difficult to move air through the lung. When this occurs, you may notice shortness of breath, chest tightness or wheezing.
  • Mucus production: In addition to the bronchoconstriction, airways of the lung produce an increased amount of mucus. This can lead to mucus plugging and further narrowing of the airways, making symptoms worse.
  • Inflammation: The inside of the airways become swollen and inflamed. This swelling even further decreases airflow and makes it more difficult to breathe. The inflammation generally occurs later in an asthma attack.

These 3 processes are what is going on in your lung during an asthma attack. If these 3 abnormalities are not treated over long periods of time, airway remodeling may lead to chronic lung damage.

Asthma Treatment Target These 3 Processes

While the best treatment is for you to avoid situations that trigger your asthma, this is not always possible. The current asthma treatments target these general processes.

Rescue medications provide relief of acute chest tightness, coughing, shortness of breath, and wheezing associated with asthma.

SABAs or short-acting bronchodilators like albuterol provide relief of acute asthma symptoms by relaxing smooth muscles in the airways of the lung. Shortly after inhalation, the smooth muscles relax, bronchoconstriction decreases, airflow increases, and your breathing becomes easier.

Anticholinergic drugs also relieve obstruction but do so by acting on different receptors in the lung.

The different receptors are the reason why these drugs take longer to produce symptom relief and their effects last longer. Because maximum bronchodilatory effect may take up to 30 minutes these drugs are not appropriate alone for immediate relief. Systemic steroids take even longer to produce an effect and last even longer than anticholinergics.

Inflammation is the other primary target of asthma meds. While there are a number of potential options, inhaled steroids are usually the first line method chosen by clinicians. 

Inhaled corticosteroids prevent asthma symptoms by blocking the late-phase immune reaction to an asthma trigger, reducing airway hyperresponsiveness,  decreasing inflammation and preventing pro-inflammatory cells such as mast cells, eosinophils, and basophils from worsening your asthma.

Understanding what is happening in an asthma attack and how your different medications may target this is the first step towards better asthma control.


Asthma. In Chest Medicine: Essentials Of Pulmonary And Critical Care Medicine. Editors: Ronald B. George, Richard W. Light, Richard A. Matthay, Michael A. Matthay. May 2005, 5th edition.

Centers for Disease Control and Prevention. Consumer Information. Asthma: General Information

National Heart, Lung, and Blood Institute. Expert Panel Report 3 (EPR3): Guidelines for the Diagnosis and Management of Asthma

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