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What is Asthma?

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

How is asthma characterized?

A person with asthma has inflamed, swollen airways.3 Inflammation makes the airways very sensitive to many things that are inhaled, called triggers. Common triggers include allergens, mold, weather, viruses, smells, and chemicals. The airways narrow when they are triggered, making it difficult to breathe.

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 a subtype that is familiar to many people. It usually starts in childhood. It may be related to other allergic diseases such as eczema, hay fever (allergic rhinitis), or food allergies.

Non-allergic asthma, which is commonly seen in adults, is not related to allergies. This subtype is harder to treat. Other types include exercise-induced, cough-variant, eosinophilic, work-related, and aspirin-induced.

What is the cause?

No one knows exactly what causes asthma.5 However, 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. Additionally, having frequent colds as a child might affect long-term lung function.

Is it possible to outgrow it?

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 However, 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 symptoms as adults.6 However, only 15% of people with severe childhood asthma were symptom-free in adulthood. It is not possible to predict who will outgrow their 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. Additionally, 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 an 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 differentiate asthma from other lung conditions. People whose airways do not narrow after inhaling methacholine are very unlikely to have asthma.

Finally, other tests may be used to figure out what subtype you have.

How is it treated?

Most people are able to control their symptoms by taking medications and avoiding triggers. In fact, with the right treatment, many people have few or no symptoms and can participate in normal activities.1 If your symptoms are under control, the risk of an attack 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: October 2019.
  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: http://www.nhlbi.nih.gov/files/docs/guidelines/asthgdln.pdf
  2. Centers for Disease Control and Prevention. Asthma Prevalence in the United States. June, 2014. Accessed 12/9/14 at: http://www.cdc.gov/asthma/asthma_prevalence_in_us.pptx
  3. National Heart, Lung, and Blood Institute. What Is Asthma? Accessed 12/8/14 at http://www.nhlbi.nih.gov/health/health-topics/topics/asthma/
  4. Global Initiative for Asthma. Global Strategy for Asthma Management and Prevention 2014. Accessed 11/12/14 at: www.ginasthma.org
  5. American Lung Association. Learning More About Asthma Accessed 12/9/14 at: http://www.lung.org/lung-disease/asthma/learning-more-about-asthma
  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