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This topic provides information about asthma in teens and adults. If you are looking for information about asthma in children age 12 and younger, see the topic Asthma in Children.

What is asthma?

Asthma causes swelling and inflammation in the airways that lead to your lungs. When asthma flares up, the airways tighten and become narrower. This keeps the air from passing through easily and makes it hard for you to breathe. These flare-ups are also called asthma attacks or exacerbations.

Asthma affects people in different ways. Some people only have asthma attacks during allergy season, or when they breathe in cold air, or when they exercise. Others have many bad attacks that send them to the doctor often.

Even if you have few asthma attacks, you still need to treat your asthma. The swelling and inflammation in your airways can lead to permanent changes in your airways and harm your lungs.

Many people with asthma live active, full lives. Even though asthma is a lifelong disease, treatment can control it and keep you healthy.

What causes asthma?

Experts do not know exactly what causes asthma. But there are some things we do know:

• Asthma runs in families.
• Asthma is much more common in people with allergies, though not everyone with allergies gets asthma. And not everyone with asthma has allergies.
• Pollution may cause asthma or make it worse.

What are the symptoms?

Symptoms of asthma can be mild or severe. You may have mild attacks now and then, or you may have severe symptoms every day, or you may have something in between. How often you have symptoms can also change. When you have asthma, you may:

• Wheeze, making a loud or soft whistling noise that occurs when you breathe in and out.
• Cough a lot.
• Feel tightness in your chest.
• Feel short of breath.
• Have trouble sleeping because of coughing or having a hard time breathing.
• Quickly get tired during exercise.

Your symptoms may be worse at night.

Severe asthma attacks can be life-threatening and need emergency treatment.

How is asthma diagnosed?

Along with doing a physical exam and asking about your health, your doctor may order lung function tests. These tests include:

• Spirometry. Doctors use this test to diagnose and keep track of asthma. It measures how quickly you can move air in and out of your lungs and how much air you move.
• Peak expiratory flow (PEF). This shows how fast you can breathe out when you try your hardest.
• An exercise or inhalation challenge. This test measures how quickly you can breathe after exercise or after taking a medicine.
• A chest X-ray, to see if another disease is causing your symptoms.
• Allergy tests, if your doctor thinks your symptoms may be caused by allergies.