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This information was reviewed and approved by Flavia Cecilia Lega Hoyte, MD (2/7/2023).

Normal AirwayAsthma is a chronic respiratory disease. It is sometimes worrisome and inconvenient, but a manageable condition. It is also known as reactive airway disease. With proper understanding, good medical care and monitoring, you can keep asthma under control.

Asthma is a chronic lung condition involving inflammation (swelling) of the airways, along with increased sensitivity of the airways to particles that make asthma worse and obstruct airflow. These symptoms can prompt an asthma attack, where regular breathing becomes difficult.

If you or your child has asthma, you’re not alone. In the United States, asthma affects 25 million people, including 6 million children, making it the most common chronic disease of childhood.

While sometimes worrisome and inconvenient, this condition is manageable. With proper understanding, good medical care and monitoring, you and your child can keep asthma under control. Our treatment goal at National Jewish Health is to teach patients and families how to manage asthma, so that they can lead full and productive lives.

There are various types of asthma, including: 


Typical Changes in the Airway

Airway with inflammationAsthma, also known as reactive airway disease, is defined as a chronic lung condition with:

  • Inflammation (swelling of the airways)
  • Increased sensitivity of the airways to a variety of things that make asthma worse
  • Obstruction of airflow


Recent research has shown that inflammation of the lining of the airways is the most common feature of asthma. When they are stimulated, certain cells lining the airways release chemical substances (mediators) that lead to inflammation. This causes the airway lining to swell and narrow. The inflammation may last for hours, days or weeks following an episode. Most people with asthma have some degree of inflammation all of the time. Some long-term control medications can help prevent and reduce inflammation.

Increased Sensitivity

Another characteristic of asthma is increased sensitivity of the airways. When inflammation occurs in the airways, they become more sensitive (or "twitchy"). When the airways are more sensitive, you are more likely to have asthma symptoms when exposed to things that can make asthma worse. The more sensitive your airways, the less it takes to cause a problem. When there is less inflammation, the airways are less sensitive, and you are less likely to have asthma symptoms when exposed to things that make asthma worse or cause asthma attacks. 

Airway with inflammation, bronchospasm and mucus productionAirway Obstruction

In addition to the swelling that occurs as a result of inflammation, further airway obstruction sometimes occurs with asthma. Obstruction is caused by the tightening of muscles that surround the airways. This is also called bronchospasm. Bronchospasm causes further narrowing of the inflamed airways. Inhaled quick-relief medications are generally very effective in reversing bronchospasm.

In most people with asthma, the mucous glands in the airways produce excessive, thick mucus, which further obstructs the airways and causes coughing.