Asthma is a chronic condition that affects the airways. It causes wheezing and breathing difficulties. There are different types, such as childhood, adult-onset, seasonal, and workplace-related asthma.

Asthma causes the inside walls of the airways, or the bronchial tubes, to become swollen and inflamed.

During an asthma attack, the airways swell, the muscles around them tighten, and it becomes difficult for air to move in and out of the lungs.

In 2019, around 7.8% of people in the United States had asthma. There are many types of this condition, and several factors can cause it or trigger an acute attack.

This article looks at the types, causes, and triggers of asthma, as well as how a doctor diagnoses it.

Learn about managing asthma here.

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Asthma is a long-term condition affecting the airways. It involves inflammation and narrowing inside the lungs, which restricts air supply.

A person living with asthma may experience:

An asthma attack occurs when the symptoms become severe. Attacks can begin suddenly and range from mild to life threatening.

In some cases, swelling in the airways can prevent oxygen from reaching the lungs. This means that oxygen cannot enter the bloodstream or reach vital organs. Therefore, people who experience severe symptoms need urgent medical attention.

A doctor can prescribe suitable treatments and advise a person on the best ways to manage their asthma symptoms.

Learn more about the signs and symptoms of asthma here.

Asthma can develop in many different ways and for many different reasons, but the triggers are often the same. They can include several broad categories, such as:

  • allergens, including dander and pollen
  • irritants, such as smoke and chemicals
  • exercise
  • other health conditions
  • weather
  • certain medications
  • strong emotions

The sections below discuss some common types of asthma:

Childhood asthma

Asthma is the most common chronic condition in children. It can develop at any age, but it is slightly more common in children than in adults.

In 2019, children aged 12–14 years were most likely to experience asthma. In this age group, the condition affected 10.8% of individuals. The second highest prevalence was in children aged 5–14 years, with an average of 9.1%.

In the same year, asthma developed in 8% of people aged 18 years or over.

According to the American Lung Association (ALA), some common triggers of childhood asthma include:

  • respiratory infections and colds
  • cigarette smoke, including secondhand tobacco smoke
  • allergens
  • air pollutants, such as ozone and particle pollution, both indoors and outside
  • exposure to cold air
  • sudden changes in temperature
  • excitement
  • stress
  • exercise

It is vital to seek medical attention if a child starts to experience asthma, as it can be life threatening. A doctor can advise on some of the best ways to manage the condition.

In some cases, asthma may improve as the child reaches adulthood. For many people, however, it is a lifelong condition.

Adult-onset asthma

Asthma can develop at any age, including during adulthood.

Some factors that affect the risk of developing asthma in adulthood include:

  • respiratory illness
  • allergies and exposure to allergens
  • hormonal factors
  • obesity
  • stress
  • smoking

Learn more about adult-onset asthma here.

Occupational asthma

Occupational asthma occurs as a result of exposure to an allergen or irritant present in the workplace. About 1 in 6 adult-onset cases of asthma start at work.

Additionally, about 21% of working adults living with asthma have found that their symptoms worsen at work. Both indoor and outdoor work environments can expose an individual to asthma triggers.

Difficult-to-control and severe asthma

A 2014 study suggests that around 5–10% of people with asthma have severe asthma.

Some individuals have severe symptoms for reasons that do not relate directly to asthma. For example, they may not yet have learned the correct way to use an inhaler.

Others have severe refractory asthma. In these cases, the asthma does not respond to treatment, even with high dosages of medication or the correct use of inhalers. This type of asthma may affect 3.6% of people with the condition.

Eosinophilic asthma is another type of asthma that, in severe cases, may not respond to the usual medications. Although some people with eosinophilic asthma manage with standard asthma medications, others may benefit from specific biologic therapies.

One type of biologic medication reduces the number of eosinophils, which are a type of blood cell involved in an allergic reaction that can trigger asthma.

Learn more about severe asthma here.

Seasonal asthma

This type of asthma occurs in response to allergens that are only in the surrounding environment at certain times of the year.

For instance, cold air in the winter or pollen in the spring or summer may trigger symptoms of seasonal asthma.

Individuals living with seasonal asthma still have the condition for the rest of the year, but they usually do not experience symptoms.

However, asthma does not always stem from an allergy.

Learn more about allergic and nonallergic asthma here.

Health experts do not know exactly what causes asthma, but genetic and environmental factors both seem to play a significant role.

Some factors, such as sensitization to an allergen, can be both a cause and a trigger. The sections below list some other causes and triggers:


According to a 2020 study, smoking during pregnancy appears to increase the risk of the fetus developing asthma later in life. Some people also experience an aggravation of asthma symptoms while pregnant.


According to a 2018 study, obesity is both a risk factor for and a disease modifier of asthma in both children and adults.

A person with obesity may experience more frequent and severe symptoms and a decreased quality of life. They may also not respond to medications as well.


Allergies develop when a person’s body becomes sensitized to a specific substance. Once the sensitization has developed, the person will be susceptible to an allergic reaction each time they come into contact with the substance.

Allergic asthma is the most common type of asthma. Inhaling an allergen typically causes a person’s asthma symptoms to occur.

Learn more about allergic asthma here.

Smoking tobacco

According to the ALA, smoking cigarettes can trigger asthma symptoms.

Moreover, secondhand smoke can cause damage to the lungs as well. This can reduce a person’s response to treatment and decrease airflow in the lungs.

Environmental factors

Air pollution, both at one’s home and outdoors, can affect the development and triggers of asthma.

Some allergens inside the house include:

  • mold
  • dust
  • animal hair and dander
  • fumes from household cleaners and paints
  • cockroaches
  • feathers

Other triggers in the home and outdoors include:

  • pollen
  • air pollution from traffic and other sources
  • ground-level ozone


Stress can give rise to asthma symptoms, but so can several other emotions. Joy, anger, excitement, laughter, crying, and other emotional reactions can all trigger an asthma attack.

Some evidence suggests that asthma may share a link with certain mental health conditions, such as depression and anxiety.

Other research has shown that long-term stress may lead to epigenetic changes that result in chronic asthma.

Genetic factors

According to the ALA, a genetic component may play a role in whether an individual will develop asthma during their lifetime.

A person who has one or both parents living with asthma is more likely than others to develop the condition.

Hormonal factors

Around 6.1% of males and 9.8% of females are living with asthma. In addition, symptoms may vary depending on an individual’s menstrual cycle and when going through changes such as menopause.

For instance, during reproductive years, a person’s symptoms may worsen during menstruation compared with other times of the month due to a decrease in progesterone and estrogen levels. Doctors call this perimenstrual asthma.

The relationship between hormones and asthma is complex, and it varies from person to person. Dropping hormone levels associated with menopause may make asthma symptoms worse or cause some people to develop asthma. Other individuals, on the other hand, may notice their asthma symptoms improve after menopause.

Hormonal activity may also impact immune activity, resulting in hypersensitivity in the airways. People with intermittent asthma may also have symptoms only some of the time.

Learn more about intermittent asthma here.

Asthma and allergy resources

To discover more evidence-based information and resources for living with asthma and allergies, visit our dedicated hub.

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A doctor will often take into account a person’s symptoms, family and personal medical history, and test results.

When the doctor makes their diagnosis, they will also note the type of asthma a person has based on their triggers.

It can be helpful for a person to keep a log of their symptoms and possible triggers to help the doctor reach an accurate diagnosis. This should include information about potential irritants in the home, school, or workplace.

The sections below discuss some other tests a doctor may conduct to help diagnose asthma:

Physical examination

The doctor will likely focus on the upper respiratory tract, the chest, and the skin. They will likely listen for signs of wheezing, which can indicate an obstructed airway and asthma.

They may also check for:

  • a runny nose
  • swollen nasal passages
  • any growths on the inside of the nose

They will also check the skin for signs of eczema or hives.

Asthma tests

The doctor may carry out a lung function test to assess how well the lungs are working.

A spirometry test is the most common type of lung function test healthcare professionals use to diagnose asthma.

A person will need to breathe in deeply and then breathe out forcefully into a tube. The tube links up to a machine called a spirometer, which shows the speed at which they expel the air from their lungs.

Other tests

Other tests for diagnosis include:

  • Challenge test: This test allows a doctor to assess how triggers such as cold air, exercise, or inhaled medications affect a person’s breathing.
  • Allergy testing: A doctor may use a skin or blood test to check for a response.
  • Blood test: A doctor may recommend a blood test to check for elevated eosinophils and immunoglobulin E, which is an antibody the immune system generates in people with allergic asthma.

A doctor may also order a FeNo test, as well as additional tests to rule out other conditions.

Treatment options for asthma are increasing and improving. The goal of treatment is to:

  • help a person breathe better
  • reduce the number of attacks
  • increase the number of activities they can engage in

A person should work with a healthcare professional to develop the most suitable treatment plan for them. Some current options for treatment include quick-relief medication and long-term control medications.

Quick-relief medications help alleviate symptoms, while long-term control medication reduces the number of attacks if a person takes it daily.

Asthma medications currently include:

  • long- and short-term bronchodilators that relax muscles around the airways
  • antibiotics for a bacterial pneumonia or bronchitis
  • anti-inflammatory medications, such as inhaled corticosteroids, for long-term maintenance, or oral steroids for an acute attack
  • a combination of bronchodilators and corticosteroids

The ALA recommends that everyone living with asthma — even exercise-induced bronchoconstriction, formerly known as exercise-induced asthma — exercise regularly. Regular exercise has several health benefits, including helping improve a person’s overall lung function and capacity.

Before starting a new exercise program, a person should consult a doctor about what activities are safe for them. It is possible the doctor will recommend a person avoid certain activities.

Otherwise, a person can generally participate in sports, exercise, and other physical activities if they take steps to control their asthma with medications.

Other suggestions for safe and effective exercising for a person to try include:

  • covering their nose and mouth during exercise in cold weather
  • making sure they adequately warm up first
  • taking time to properly cool down afterward
  • avoiding activities outside when air quality is poor

If a person experiences pain at any time during exercise, they should stop and use a fast-acting inhaler. If symptoms get worse, they should contact a doctor.

Asthma is a chronic inflammatory condition that causes swelling in the airways. It can affect people of any age, and the symptoms can range from mild to severe.

In most cases, effective treatment can help a person with asthma live a full and active life.

Learn about some options for treating asthma here.

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