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What Is Asthma?

Asthma (pronounced: AZ-muh) is a condition that affects the airways. People with asthma have breathing problems that come and go. They may cough, wheeze, or be short of breath. This happens because airways get swollen, narrowed, and filled with mucus.

Asthma is common and tends to run in families. It can be mild or so severe that it gets in the way of daily activities.

With medicine and the right care plan, asthma symptoms can be managed so that people who have it can do just about anything they want to do.

What Causes Asthma?

No one knows exactly why some people develop asthma. Experts think it might be due to a combination of things in the environment and a person’s genes.

People with asthma may have a parent or other close relative with asthma. It’s also more likely in people who have allergic conditions (such as eczema, hay fever, and food allergies) or are overweight or obese. Events early in life seem to be related to a person developing asthma later, such as premature birth, low birth weight, exposure to cigarette smoke, and getting sick with some types of viral infections.

How Does Asthma Affect Breathing?

Normally, when someone inhales (breathes in), air goes in through the nose or mouth, down the trachea, and into the airways of the lungs. When people exhale (breathe out), air exits the body in the opposite direction.

In asthma, the airways are always a little inflamed (irritated and swollen), even when a person has no symptoms. They’re also quick to react to certain things (“triggers”) that make them get even more inflamed, swollen, and filled with mucus, blocking the flow of air. The muscles around the airways tighten, making them even narrower, which makes it very hard to breathe. When this happens, it is called an asthma flare-up or asthma attack.

Triggers vary from person to person, but common ones include:

  • respiratory infections, like colds or the flu
  • allergies to things like pollen, mold, and pet dander
  • irritants and pollutants in the air, like cigarette smoke or smog
  • weather conditions, like cold and dry air, or hot and humid air
  • strong emotions, like laughing, crying, or feeling stressed
  • exercise

What Are the Signs & Symptoms of Asthma?

Asthma symptoms include:

  • a cough, especially at night or while active
  • trouble breathing
  • a tight chest

Some people might not have asthma symptoms at all between flare-ups. Others might always have mild symptoms that get worse during a flare-up. Some flare-ups are mild, but others can be serious. They can happen suddenly, but usually build up over time.

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How Is Asthma Diagnosed?

To diagnose asthma, doctors will ask about a person's health, breathing problems, and family medical history. They'll also ask about any allergies, illnesses, and exposure to things that may make breathing worse.

The doctor will do an exam and may order a lung function test. This usually involves a breathing test called spirometry (pronounced: spye-RAH-muh-tree) that analyzes airflow through the airways.

How Is Asthma Treated?

There's no cure for asthma, but it can be managed to prevent flare-ups. Some people can outgrow asthma as they get older, but it’s still important to have it under control early in life. Asthma treatment involves two important things: avoiding triggers and taking medicine.

Avoiding Triggers

There are many ways to avoid triggers after they’re identified. Your doctor will work with you to create a plan to help you avoid them.

For example, if pet dander or mold in your home trigger your asthma symptoms, help make your home asthma-safe by changing the linens often, vacuuming regularly, and keeping pets out of your bedroom. If outdoor allergies like pollen are a problem, avoid the outdoors on days when pollen counts are high.

If exercise is a trigger, the doctor may prescribe a medicine for you to take before physical activity to prevent airways from tightening up. It’s important for people with asthma to stay active and not avoid physical activity. Exercise can help them stay healthier overall (in fact, many pro athletes have asthma).

Getting a yearly flu vaccine and a COVID-19 shot is also important, as illnesses like the flu and COVID-19 can trigger asthma flare-ups.

Taking Medicine

Most asthma medicines are breathed directly into the lungs (inhaled), but some are pills or liquids. Asthma medicines generally work in two ways:

  • Bronchodilators work right away to relax the muscles around the airways and open them, providing quick relief of symptoms. That's why they're often called quick-relief, "fast-acting," or "rescue" medicines.
  • Anti-inflammatory medicines work over time to ease inflammation, which reduces swelling of the airways and limits mucus production. They usually need to be taken every day, even when a person feels fine and has no symptoms. These are often called long-term control, "controller," or "maintenance" medicines. Some people with mild asthma might use anti-inflammatory medicines only during times of increased symptoms instead of every day.

Some people will get both types of medicines from one inhaler device. They might need to use this “combination” inhaler every day, with added doses from it when they have symptoms. Someone with mild asthma might use a combination inhaler only for quick relief when they have symptoms, or before they exercise. Your health care team will be able to help you figure out which inhaler is best, and how and when you should use it.

During a more severe flare-up, sometimes a doctor will prescribe oral (taken by mouth) steroids for 5–7 days. These work more quickly to reduce inflammation when inhaled medicines aren’t quite enough.

What Else Should I Know?

An asthma action plan is a care plan that you'll develop with the doctor. The plan gives detailed instructions on how to manage asthma, including:

  • what medicines you need and when
  • what your triggers are and how to avoid them
  • how to manage a flare-up
  • when to get emergency medical care

Following the plan can help you do normal everyday activities without having asthma symptoms.

Keeping an asthma diary is another way to help manage asthma. Tracking your symptoms and medicines will help you know when you're more likely to have a flare-up.

Asthma care takes a bit of work. But if you follow your asthma action plan, take your medicines properly, recognize your symptoms and triggers, and check in with your doctor regularly, you can do anything that people without asthma do.

Medically reviewed by: Elana Pearl Ben-Joseph, MD
Date reviewed: September 2023