Asthma is a chronic (long-term) condition that affects the airways in the lungs. The airways are tubes that carry air in and out of your lungs. If you have asthma, the airways can become inflamed and narrowed at times.
Asthma affects people of all ages and often starts during childhood. You may wheeze, cough, or feel tightness in your chest. These symptoms can range from mild to severe and can happen every day or only once in a while. Certain things can set off or worsen asthma symptoms, such as cold air. These are called asthma triggers. When symptoms get worse, it is called an asthma attack.
An asthma action plan can help you manage your asthma. The plan may include monitoring, avoiding triggers, and using medicines.
Find asthma guides, tip sheets, and other resources from NHLBI’s Asthma Learn More Breathe Better program.
The exact cause of asthma is unknown, and the causes may vary from person to person. However, asthma is often the result of a strong response of the immune system to a substance in the lungs. To understand asthma, it helps to understand How the Lungs Work.
Normally, the body’s immune system helps to fight infections. Sometimes a person’s immune system responds to a substance in the environment called an allergen. When someone breathes in an allergen, such as ragweed, the immune system in the airways may react strongly. Other people exposed to the same substance may not react at all.
The immune system reacts to an allergen by creating inflammation. Inflammation makes your airways swell and narrow and possibly produce more mucus. This can make it harder to breathe. The muscles around the airways may also tighten, which is called a bronchospasm. This can make it even harder to breathe.
Over time, the airway walls can become thicker. The image below shows how airways narrow during asthma.
Your asthma may have been caused partly by a viral infection or allergens in the air when you were a baby or young child. During this stage of life, your immune system is still developing.
It’s not clear why one person reacts to an exposure while others do not. Genes seem to play a role in making some people more susceptible to asthma.
Your environment or occupation, your family history or genes, other medical conditions, your race or ethnicity, or your sex may raise your risk for developing asthma.
Asthma affects people of all ages, but it often starts during childhood. Sometimes asthma develops in adults, particularly women. This type of asthma is called adult-onset or late-onset asthma.
Things in your environment, including at work or home, may raise your risk of developing asthma or make asthma symptoms worse.
Genes may play a role in the development of asthma because they affect how the immune system develops. More than one gene is likely involved. You inherit genes from your parents. Having a parent who has asthma, especially if the mother has asthma, increases the risk that a child will develop asthma.
Asthma is often linked to other medical conditions, such as:
African Americans and Puerto Ricans are at higher risk of asthma than people of other races or ethnicities. African American and Hispanic children are more likely to die from asthma-related causes than non-Hispanic white Americans.
Among children, more boys than girls have asthma. Among teens and adults, asthma is more common among women than men.
How often signs and symptoms of asthma occur may depend on how severe, or intense, the asthma is and whether you are exposed to allergens. Some people have symptoms every day, while others have symptoms only a few days of the year. For some people, asthma may cause discomfort but does not interfere with daily activities. If you have more severe asthma, however, your asthma may limit what you are able to do.
When asthma is well controlled, a person shows few symptoms. When symptoms worsen, a person can have what is called an asthma attack, or an exacerbation. Over time, uncontrolled asthma can damage the airways in the lungs.
Signs and symptoms of asthma may include:
While other conditions can cause the same symptoms as asthma, the pattern of symptoms in people who have asthma usually has some of the following characteristics.
Asthma attacks, or exacerbations, are episodes that occur when symptoms get much worse and require a change in typical treatment. These can come on gradually or suddenly and may be life-threatening. People who have severe asthma often get asthma attacks more often.
Asthma is diagnosed based on your medical history, a physical exam, and results from diagnostic tests. You may need to see a team of healthcare providers, including your doctor; an asthma specialist, called a pulmonologist; or an allergy specialist, called an allergist.
Your doctor will ask about your risk factors for asthma and your symptoms. They may ask also about any known allergies. This includes how often symptoms occur, what seems to trigger your symptoms, when or where symptoms occur, and if your symptoms wake you up at night.
During the physical exam, your doctor may:
Your doctor may ask you to perform the following tests to determine whether your symptoms are caused by asthma.
It can be hard to tell whether a child under age 6 has asthma or another respiratory condition, because young children often cannot perform a pulmonary function test such as spirometry. After checking a child’s history and symptoms, the doctor may try asthma medicines for a few months to see how well a child responds. About 40% of children who wheeze when they get colds or respiratory infections are eventually diagnosed with asthma.
If you are diagnosed with asthma, your doctor will work with you to create a treatment plan to manage your asthma symptoms and prevent asthma attacks. Treatment usually depends on your age, asthma severity, and response to a given treatment option. Your doctor may adjust your treatment until asthma symptoms are controlled.
Most people are treated long-term with daily controller(s), along with another inhaler for short-term relief, when they have symptoms or to prevent symptoms. An inhaler allows the medicine to go into the mouth and airways.
Watch our video to learn about treatment for asthma.
Short-term relief medicines, also called quick-relief medicines, help prevent symptoms or relieve symptoms during an asthma attack. They may be the only medicines needed for mild asthma or asthma that happens only with physical activity.
Your doctor will prescribe a quick-relief inhaler for you to carry at all times. Visit the Centers for Disease Control and Prevention (CDC) to learn how to use your asthma inhaler correctly.
Types of short-term relief medicines include:
Your doctor may prescribe long-term control medicines to take daily to help prevent symptoms by reducing airway inflammation and preventing narrowing of the airways. Treatment with specific control medicines may differ depending on age, such as whether the person is an adult or child. Return to Causes to review what causes asthma symptoms.
Control medicines include the following.
If you have a severe asthma attack and need emergency care, you may be treated with medicines, such as those listed above, given with a nebulizer or IV. You may also receive oxygen therapy or breathing assistance. This may include ventilator support or through a mask with forced air.
In certain cases, your doctor may recommend a procedure called bronchial thermoplasty if you are 18 years or older and have severe asthma that remains uncontrolled despite using other treatments. In this procedure, your doctor will insert a bronchoscope into your airway through the mouth or the nose. This helps your doctor see inside the airways. Heat is used to reduce the muscle around the airway to help prevent constriction. Read more about bronchial thermoplasty in our fact sheet.
After being diagnosed with asthma, work with your doctor to learn how to manage it yourself. Because asthma symptoms may be different at different times, it is important to know which medicines to use to prevent and relieve symptoms. You can work with your doctor to develop a treatment plan, called an asthma action plan. Follow-up care will help to make sure your or your child’s asthma is well-controlled. Staying healthy also includes avoiding asthma triggers and maintaining a healthy lifestyle.
Watch NHLBI’s video Living with and Managing Asthma for more information.
Work with your doctor to create an asthma action plan that works for you. An asthma action plan is a written treatment plan document that describes the following.
If your child has asthma, then your child’s caretakers and school staff should know about the asthma action plan. For a sample plan, see the National Heart, Lung, and Blood Institute’s (NHLBI) Asthma Action Plan.
Your doctor will make sure you are using your inhaler correctly. There are different types of inhalers. Review the way you use your inhaler at every medical visit. Sometimes asthma may get worse because of incorrect inhaler use.
Watch our video on Asthma Action Plans to learn more. Then, download a sample Asthma Action Plan.
Asthma triggers are things that set off or worsen asthma symptoms. If you know that your asthma symptoms occur when you are exposed to specific triggers, it may be worthwhile to reduce your exposure to those triggers, using multiple different methods to reduce the exposure.
Allergens are a common trigger for asthma.
Other asthma triggers include:
Regular checkups are important to help your doctor determine how well you are controlling your asthma and adjust treatment if needed. Your doctor will also do regular tests to see how well your lungs are working and how well air is flowing.
Your medicines or dosages may change over time, based on changes in your condition or in your life, such as:
Return to Treatment to review possible treatment options for your asthma.
Ask your doctor about asthma training or support groups to help you keep asthma under control. Education can help you understand the purpose of your medicines, how to prevent symptoms, how to recognize asthma attacks early, and when to seek medical attention.
As part of your asthma action plan, your doctor may show you how to monitor your asthma using a peak flow meter. You can compare your numbers over time to make sure your asthma is controlled. A low number can help warn you of an asthma attack, even before you notice symptoms.
Keeping a diary may help if you find it hard to follow your asthma action plan or the plan is not working well. If you have any of the following experiences, record them in the diary and make an appointment to see your doctor. Bring the diary with you to your appointment.
If your young child’s asthma is not well-controlled, you may notice that he or she is coughing more at night and eating less. Your child also may seem more tired (called fatigue), irritable, or moody.
Your doctor may recommend one or more of the following heart-healthy lifestyle changes to help keep asthma symptoms in check.
Your doctor may recommend that you keep your medicine dose as low as possible to prevent long-term side effects. High doses of certain asthma medicines over time can increase your risk of cataracts and osteoporosis. A cataract is the clouding of lens in your eye. Osteoporosis is a disorder that makes your bones weak and more likely to break. Read more in What People With Asthma Need To Know About Osteoporosis.
Keep your asthma under control and contact your doctor if anything changes. When asthma is unmanaged, it can lead to potentially life-threatening asthma attacks. If you are pregnant, it can put the health of your unborn baby at risk.
A written asthma action plan developed with your doctor can help you know when to call 9-1-1 for emergency care.
Asthma attacks can be more dangerous for some people. You should seek care immediately during an asthma attack if you or your child:
For young children with asthma, call 9-1-1 if they:
Call your doctor if:
Learn about the following ways the NHLBI continues to translate current research into improved health for people who have asthma. Research on this topic is part of the NHLBI’s broader commitment to advancing scientific discovery for lung disease and health disparities and inequities.
In support of our mission, we are committed to advancing asthma research in part through the following ways.
Learn about exciting research areas that the NHLBI is exploring about asthma.
We lead or sponsor many studies on asthma. See if you or someone you know is eligible to participate in our clinical trials.
To learn more about clinical trials at the NIH Clinical Center or to talk to someone about a study that might fit your needs, call the Office of Patient Recruitment 800-411-1222.
After reading our Asthma Health Topic, you may be interested in additional information found in the following resources.