Asthma: symptoms, triggers, tests and action plans

Medical disclaimer: This page is general health information for education only. It is not medical advice and is not a substitute for diagnosis or treatment by a qualified health professional. It has not been reviewed by a clinician. In an emergency, call 911 or your local emergency number.

Asthma is a chronic condition that affects the airways in your lungs. The airways can become inflamed and narrowed at times, which makes breathing harder. This guide explains what happens in the airways, which symptoms and triggers to watch for, how clinicians diagnose asthma, and how an asthma action plan works. It is written for adults with asthma and for parents of children with asthma. It sits within our library of common health conditions.

What is asthma?

Asthma is a long-term lung disease that affects the airways, the tubes that carry air in and out of your lungs.

• About 1 in 13 people in the United States have asthma, according to the National Heart, Lung, and Blood Institute (NHLBI).
• Asthma affects people of all ages and often starts during childhood.
• WHO estimates asthma affected 363 million people worldwide in 2023.
• Asthma is the most common chronic disease among children, according to the World Health Organization asthma fact sheet.

There is no cure for asthma. Treatment and an asthma action plan can help people manage it. This page gives general information only. It does not tell you whether you or your child has asthma.

If your symptoms started in adulthood, see our guide to adult onset asthma.

What happens in your airways during asthma

During an asthma flare, the airway lining swells, the muscles around the airways tighten, and mucus builds up.

• Inflammation: The inner lining of the airways becomes swollen.
• Tightening: The muscles surrounding the airways get bigger and tighten.
• Mucus: Glands in the airways produce lots of thick mucus.

These three changes are described in the NHLBI patient guide So You Have Asthma. Together they narrow the airways, so less air moves in and out of the lungs. The CDC notes that mucus can clog the airways during an asthma attack. An asthma attack is a flare in which symptoms get worse. This description covers asthma only. Other lung conditions, such as COPD and emphysema, also narrow the airways but have different causes and care.

Common asthma symptoms and triggers

The main asthma symptoms are wheezing, coughing, shortness of breath, and chest tightness.

The NHLBI lists these asthma symptoms:

• Wheezing, which is a whistling sound when you breathe out
• Coughing, especially at night or early morning
• Shortness of breath
• Chest tightness

Asthma symptoms often come and go over time or within the same day. They are often worse at night or in the morning.

A trigger is something that sets off asthma symptoms or an attack. Common triggers named by the NHLBI causes and triggers page include:

• Indoor allergens, such as dust mites, mold, and pet dander
• Outdoor allergens, such as pollen and mold
• Colds, the flu, or COVID-19
• Physical activity and emotional stress
• Poor air quality or very cold air
• Certain medicines, such as aspirin

People who have asthma often have other allergies, such as pollen allergies, according to NHLBI. Our page on allergic rhinitis and hay fever explains that condition. These symptoms are not unique to asthma. Other illnesses can cause a cough or wheeze, so a clinician needs to evaluate them.

How asthma is diagnosed

Clinicians diagnose asthma by asking about your symptoms and risk factors and by using breathing tests such as spirometry.

The NHLBI asthma diagnosis page names these tests:

Most diagnostic tests for asthma do not work well for young children. Young children often cannot do a spirometry test, according to the NHLBI page on asthma in children. It can be hard to tell whether a child under age 6 has asthma or another breathing condition. This table is not a complete list. A clinician decides which tests fit each person.

What an asthma action plan is

An asthma action plan is a written plan, made with your health care provider, that tells you what to do as symptoms change.

The NHLBI treatment and action plan page says a plan describes:

• How to identify your triggers
• How to recognize an asthma attack
• Which medicines to take and when
• When to seek emergency care
• Whom to contact during an emergency

The CDC asthma action plan form uses three zones. The Green Zone means no symptoms and you can do your usual activities. The Yellow Zone means one or more symptoms, such as coughing, wheezing, or waking up at night. The Red Zone is an emergency.

The CDC says everyone with asthma needs their own asthma action plan. A plan written for one person does not apply to anyone else. Parents can ask the clinician whether to share a copy with caregivers and school staff.

Long-term control and quick-relief medicines

Most people with asthma use two kinds of medicine: long-term control medicines and quick-relief medicines.

• Long-term control medicines are taken every day to help prevent symptoms. They work by reducing airway inflammation, according to MedlinePlus.
• Quick-relief medicines help prevent symptoms or relieve symptoms during an asthma attack.
• Long-term control medicines do not help during an asthma attack, according to NIH MedlinePlus Magazine.

Inhaled corticosteroids are one type of medicine that reduces inflammation. Your clinician chooses the medicines, the device, and the amount. This page does not give doses or tell you to start, stop, or change any medicine. The MedlinePlus encyclopedia advises talking with your provider if you use quick-relief medicine twice a week or more.

Emergency warning signs of a severe asthma attack

Call 911 if asthma medicines are not relieving symptoms during an attack or breathing is still very hard.

Signs of a severe asthma attack that need emergency care include:

• Trouble walking or talking because of shortness of breath
• Lips or fingernails that look blue, pale, or gray
• Extreme difficulty breathing or severe shortness of breath at rest
• Drowsiness or confusion
• A rapid pulse

These signs come from the CDC asthma action plan and the MedlinePlus asthma encyclopedia entry. For young children, the NHLBI asthma attack page says to call 911 if a child seems drowsy, confused, or troubled, has a blue tint to the skin and lips, or has a fast heartbeat.

Do not wait to see if these signs pass. This list does not cover every emergency. If you are unsure, call 911. Our first aid guide covers other urgent situations.

Questions to bring to your appointment

These questions can help you or your child’s clinician talk through asthma care. They do not replace the clinician’s advice.

• Which tests do you recommend to confirm asthma, and what do the results mean?
• What are my (or my child’s) main triggers, and how can we reduce contact with them?
• Can we write or update an asthma action plan together?
• Which of my medicines is for long-term control and which is for quick relief?
• Can you check how I use my inhaler?
• Which warning signs mean I should call you, and which mean I should call 911?