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What is Asthma?

Asthma is a common disorder of the airways.1 About 25.7 million people in the United States have asthma, including seven million children.2 Some people use the term “bronchial asthma” to describe this disease.

A person with asthma has inflamed, swollen airways.3 Inflammation makes the airways very sensitive to many things that are inhaled, called triggers. Allergens, mold, weather, viruses, or chemicals are common triggers. When the airways are triggered, they begin to narrow, making it difficult to breathe. Asthma symptoms include coughing, wheezing, shortness of breath, and chest tightness.1 You may have some or all of these symptoms.1 Often, symptoms are the worst at night or in the morning.4 Symptoms may get better with little or no treatment. Other times, they can become very intense, called an asthma attack.

What are the different types of asthma?

There are many different types of asthma with different causes and symptom patterns.4 Allergic asthma is the type of asthma that is familiar to many people. Allergic asthma usually starts in childhood. It may be related to other allergic diseases such as eczema, hay fever (allergic rhinitis), or food allergy.

Non-allergic asthma is seen in adults with asthma that is not related to allergy. This type of asthma is harder to treat. Other types of asthma include exercise-induced asthma, cough-variant asthma eosinophilic asthma, work-related asthma, and aspirin-induced asthma.

What causes asthma?

No one knows exactly what causes asthma.5 It runs in families, so there may be a genetic link. Exposure to certain allergens, viruses, chemicals, and secondhand smoke before birth or as an infant might have a role. These exposures might change the way the immune system develops. Having frequent colds as a child might affect long-term lung function.

Is it possible to outgrow asthma?

Asthma is a long-term (chronic) disease. You may feel better for months, but generally, the airways remain inflamed and sensitive.

Some children do seem to outgrow their symptoms.1 Other children need to continue taking medications to control their asthma. In one study, 64% of people with mild childhood asthma symptoms did not have asthma as adults.6 However, only 15% of people with severe childhood asthma were asthma free in adulthood. It is not possible to predict who will outgrow their asthma symptoms.

How is asthma diagnosed?

Asthma is diagnosed based on symptoms, physical examination, and lung function tests.1 4 Your health care provider will ask about the type and frequency of symptoms and what you were doing when the symptoms started. Your provider may do a test called spirometry. This test checks how much and how quickly you can exhale air.

It is possible for a person with a history of asthma symptoms to have normal spirometry results.1 In this case, your health care provider may suggest a methacholine challenge. Methacholine is a inhalable spray that is especially irritating to people with asthma. It triggers airway narrowing and allows your provider to measure how sensitive your airways are. The methacholine challenge is best for ruling out asthma, although the results are not always conclusive. The test also helps to distinguish asthma from other lung conditions. People whose airways do not narrow after inhaling methacholine are very unlikely to have asthma. If your airways are sensitive, it could be a sign of asthma.

Other tests might be used to figure out what type of asthma you have.

How is asthma treated?

Most people are able to control their asthma symptoms by taking medications and avoiding triggers. With the right treatment, many people with asthma have few or no symptoms and can participate in normal activities.1 If your asthma is under control, the risk of asthma attacks and hospitalization is much lower.

One or more medications may be needed to treat asthma.4 Inhaled corticosteroids are taken each day to reduce inflammation. Long-acting beta-agonists are daily medications that open the airways. Short-acting beta-agonists are taken as needed for quick symptom relief. Several other drugs are available that work in different ways to manage asthma.

It is important that you follow the instructions for using your inhaler and take your medications as recommended. If you are doing these things and you still have symptoms, your health care provider may recommend adding another drug or switching to a different treatment.

Written by: Sarah O'Brien | Last Reviewed: May 2016.
  1. National Heart, Lung, and Blood Institute. Expert panel report 3 (EPR-3): Guidelines for the diagnosis and management of asthma - Full Report 2007. Accessed 11/12/14 at:
  2. Centers for Disease Control and Prevention. Asthma Prevalence in the United States. June, 2014. Accessed 12/9/14 at:
  3. National Heart, Lung, and Blood Institute. What Is Asthma? Accessed 12/8/14 at
  4. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention 2014. Accessed 11/12/14 at:
  5. American Lung Association. Learning More About Asthma Accessed 12/9/14 at:
  6. Tai A, Tran H, Roberts M, et al. Outcomes of childhood asthma to the age of 50 years. J Allergy Clin Immunol. 2014;133:1572-8.e3. Abstract