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Asthma Lungs

What is Asthma?

Asthma is a chronic, or long-term, disease that affects the airways in a person’s lungs. It inflames and narrows the airways, making it difficult to breathe.[i] The exact cause of asthma is unknown and may vary from person to person, but it is often the result of a person’s immune response to substances in the lungs.

What are the symptoms?

Common asthma symptoms include coughing, wheezing, shortness of breath or chest tightness. Some people may have symptoms every day, while others only experience symptoms a few times per year. For many people with asthma, symptoms can be intensified due to triggers, such as pollen, mold, smoke or even exercise, which can cause an asthma attack.[ii]

For a list of symptoms and to learn more about asthma, visit

Who can be impacted by asthma?

More than 25 million or 1 in 12 people in the U.S. have asthma and the numbers are increasing every year. [ii] Asthma often starts during childhood but affects people of all ages. [iii]

While we don’t know what causes asthma, genetic, environmental and occupational factors are known to play a role in a person’s likelihood to develop asthma. Atopy, the genetic tendency to develop an allergic disease, can also impact whether a person will develop allergic asthma.

What are the types of asthma?

Not all asthma is the same, it can be different for different people. Learn more about uncontrolled asthma and severe eosinophilic asthma.

Asthma stat card

Uncontrolled Asthma

While many people can effectively manage their asthma, some continue to experience symptoms that impact everyday life. Frequent symptoms such as shortness of breath and coughing despite appropriate treatment could be a sign of uncontrolled asthma.[i] As people live with these symptoms throughout their life, they begin to accept them as normal and deal with the subsequent impact, like difficulty performing daily tasks or resulting in a person missing work.

People living with asthma should not have to settle for persistent symptoms. It is critical that patients and their healthcare teams have open and honest communication that delves beyond the routine to truly understand the burden of symptoms on day-to-day life. This can help patients develop a better treatment plan and better manage the disease to live a more active life.

Eosinophils are a type of white blood cell

Severe Eosinophilic Asthma

Some forms of asthma may have an underlying cause, like elevated eosinophil levels, causing lung inflammation. Eosinophils are white blood cells that are part of the body’s normal immune system, and research has shown that an elevated number of these cells may cause inflammation and swelling in the airways, which can increase the risk of asthma attacks.

Eosinophils are measured through a simple blood test and the results determine the number of eosinophils in a person’s blood and informs their diagnosis. About half of people with severe asthma have elevated levels of eosinophils, giving the condition its name – severe eosinophilic asthma.[i]

[i] National Heart, Lung and Blood Institute. Asthma. Available at:

[ii] American College of Allergy, Asthma & Immunology. Asthma Attack. Available at:

[iii] Centers for Disease Control and Prevention. Asthma in the US. Available at:

[iv] National Heart, Lung and Blood Institute. Asthma. Available at:

[v] Centers for Disease Control and Prevention. Uncontrolled Asthma among Adults, 2016. Available at:

[vi] Kerkhof M;Thorax;2017;73;116-124 (v1.0) - Results (p.1)