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What Is Asthma?

Asthma (AZ-ma) is a chronic (long-term) lung disease that inflames and narrows the airways. Asthma causes recurring periods of wheezing (a whistling sound when you breathe), chest tightness, shortness of breath, and coughing. The coughing often occurs at night or early in the morning.

Asthma affects people of all ages, but it most often starts during childhood. In the United States, more than 25 million people are known to have asthma. About 7 million of these people are children.

Overview

To understand asthma, it helps to know how the airways work. The airways are tubes that carry air into and out of your lungs. People who have asthma have inflamed airways. This makes them swollen and very sensitive. They tend to react strongly to certain inhaled substances.

When the airways react, the muscles around them tighten. This narrows the airways, causing less air to flow into the lungs. The swelling also can worsen, making the airways even narrower. Cells in the airways might make more mucus than usual. Mucus is a sticky, thick liquid that can further narrow the airways.

This chain reaction can result in asthma symptoms. Symptoms can happen each time the airways are inflamed.

Asthma

Figure A shows the location of the lungs and airways in the body. Figure B shows a cross-section of a normal airway. Figure C shows a cross-section of an airway during asthma symptoms.

Figure A shows the location of the lungs and airways in the body. Figure B shows a cross-section of a normal airway. Figure C shows a cross-section of an airway during asthma symptoms.

Sometimes asthma symptoms are mild and go away on their own or after minimal treatment with asthma medicine. Other times, symptoms continue to get worse.

When symptoms get more intense and/or more symptoms occur, you're having an asthma attack. Asthma attacks also are called flareups or exacerbations (eg-zas-er-BA-shuns).

Treating symptoms when you first notice them is important. This will help prevent the symptoms from worsening and causing a severe asthma attack. Severe asthma attacks may require emergency care, and they can be fatal.

Outlook

Asthma has no cure. Even when you feel fine, you still have the disease and it can flare up at any time.

However, with today's knowledge and treatments, most people who have asthma are able to manage the disease. They have few, if any, symptoms. They can live normal, active lives and sleep through the night without interruption from asthma.

If you have asthma, you can take an active role in managing the disease. For successful, thorough, and ongoing treatment, build strong partnerships with your doctor and other health care providers.

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Join the NHLBI in Observing Asthma Awareness Month

May is Asthma Awareness Month. Together we can help control asthma. During Asthma Awareness Month the National Asthma Education and Prevention Program (NAEPP) encourages you to discover how. Visit the NACI’s WAD Web page for more asthma related info.

Join the NHLBI's Asthma Awareness Twitter Chat with U.S. News on May 14 from 2:00-3:00 p.m. EDT. Other participants include representatives from the Office of the Surgeon General, the Centers of Disease Control and Prevention, the University of Wisconsin, and the American Thoracic Society. Follow the chat using the #AsthmaChat hashtag.

Asthma Clinical Trials

Clinical trials are research studies that explore whether a medical strategy, treatment, or device is safe and effective for humans. To find clinical trials that are currently underway for Asthma, visit www.clinicaltrials.gov.

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Visit Children and Clinical Studies to hear experts, parents, and children talk about their experiences with clinical research.


Asthma in the News

May 18, 2014
NHLBI Media Availability: Vitamin D supplementation does not reduce asthma treatment failure in people with low Vitamin D, but some benefits suggested.
Supplementing inhaled corticosteroids (ICS) with vitamin D does not reduce the rate of treatment failure in patients with asthma and vitamin D insufficiency, finds a new NIH-funded study. The Vitamin D Add-on Therapy Enhances Corticosteroid Responsiveness in Asthma (VIDA) trial randomized 408 adults with low vitamin D and mild/moderate asthma to receive the ICS ciclesonide supplemented with either high-dose vitamin D3 or placebo.

View all Asthma Press Releases

 
June 15, 2012 Last Updated Icon

The NHLBI updates Health Topics articles on a biennial cycle based on a thorough review of research findings and new literature. The articles also are updated as needed if important new research is published. The date on each Health Topics article reflects when the content was originally posted or last revised.