Health experts don’t know exactly what causes asthma. However, certain factors are associated with increased asthma risk.

Asthma is a chronic (long-term) disease of the lungs that causes inflammation and narrowing of the airways.

While the exact causes of asthma are not known, health experts believe that both genetic and environmental factors can contribute to asthma.

These factors include:

  • family history
  • viral respiratory infections
  • exposure to allergens, chemicals, or smoke
  • sex, age, and race and ethnicity
  • allergic conditions such as eczema and hay fever
  • overweight and obesity

It’s common for people with asthma to have allergies as well, but not everyone who has allergies will develop asthma.

In this article, we review what researchers currently know about the risk factors and causes of asthma and what you can do to help avoid possible asthma triggers.

A note on language

Sex and gender exist on spectrums. This article uses the terms “female” and “male” to refer to sex assigned at birth. However, this category is more complex than a male-female binary. Learn more here.

Several factors may increase your risk of developing asthma.

Family history

If one of your parents has asthma, you may be 3–6 times more likely to develop it than someone whose parents do not have it. This can reflect the underlying genetic components of asthma as well as shared living conditions.

It’s thought that multiple genes may be involved in asthma development, and you can inherit these from your parents.

The risk of developing asthma may be highest if your birthing parent also has it, or if both of your biological parents have it.

Demographic categories: Age, sex, and race and ethnicity

Asthma is more common in children than in adults. Most children with asthma develop it before age 5.

According to the National Heart, Lung, and Blood Institute, male children are more likely to develop asthma than female children. However, adult females are more likely to develop adult-onset asthma.

Additionally, the Asthma and Allergy Foundation of America (AAFA) reports that Black, Hispanic, Native American, and Alaska Native people have the highest rates of asthma in the United States and are more likely to experience severe complications, including hospitalization and death.

The AAFA notes that systemic racism is largely responsible for the disparities in living conditions and healthcare access that drive these differences.

For example, research presented to the American Thoracic Society suggests that biases encoded in lung function (spirometry) tests make it less likely that Black people will receive adequate care for lung conditions.


Certain allergic conditions, such as atopic dermatitis (eczema) and hay fever (allergic rhinitis), are considered risk factors for developing asthma.

Having a sensitivity to allergens such as the following may mean that you’re more likely to develop asthma:

  • dust mites
  • pet dander
  • mold spores
  • pollen
  • foods

Allergens can also trigger asthma attacks after you develop asthma.


Cigarette smoke leads to lung irritation, and people who smoke have a higher risk of developing asthma.

People who were exposed to secondhand smoke during childhood or whose birthing parent smoked during pregnancy are also more likely to have asthma.

Air pollution

Repeated exposure to ozone, a gas found in polluted air, is believed to increase the risk of asthma.

Additionally, children who live in urban areas are more likely to develop severe asthma than those who do not live in these areas.

Occupational exposures

Exposure to certain chemicals, gases, or allergens may increase your risk of developing occupational (work-related) asthma.

In fact, this asthma subtype has become so common in the United States that it’s estimated that 15% of all asthma cases may be job-related.

People who do the following types of work are considered higher risk for this type of asthma:

  • baking
  • grain processing or milling
  • drug and detergent manufacturing
  • farming
  • working with laboratory animals
  • working with plastics and metal
  • woodworking

Occupational asthma may take months or years to develop, but it’s possible to start having symptoms much more quickly. In some cases, lung issues can persist even after you’re no longer exposed to the irritants or allergens.

Also, if you already have asthma, occupational exposure to dust, fumes, or chemicals may make it worse.


In both children and adults, obesity and overweight have been linked to an increased risk of developing asthma. People with obesity are more likely to have severe asthma that’s difficult to manage.

It’s thought that low grade inflammation in the body may contribute to this risk factor.

Viral respiratory infections

Some children develop asthma after recovering from a viral respiratory infection. This may be due to changes that these illnesses can cause in a child’s developing lungs or immune system.

A viral infection called bronchiolitis has been specifically linked to increased asthma risk in children.

Certain childhood conditions

Children who were born preterm (prematurely) have an increased risk of developing asthma, particularly if they needed breathing assistance from a ventilator.

Low birth weight also increases the risk of developing asthma.

Researchers have identified the two main conditions that cause asthma symptoms: inflammation and airway constriction. While symptoms may vary in intensity, they tend to be worse at night and in the early morning.


Asthma causes inflammation of the inside walls of your airways. This makes the air passages particularly sensitive to irritants and asthma triggers.

Airway constriction

When air passages in your lungs are exposed to asthma triggers, the muscles surrounding your airways tighten. This narrows your airways, which makes it hard to breathe and creates a tight feeling in your chest. Mucus production also increases.

The triggers that cause inflammation and airway constriction can vary from person to person. Understanding your triggers is essential to managing asthma.

Common asthma triggers include:

You may find it helpful to work with your doctor to figure out your triggers and then come up with strategies to avoid them.

Your asthma management plan may also include a combination of quick-relief and long-term medications to manage asthma and prevent asthma attacks.

Asthma is a long-term disease that causes inflammation in the air passages in your lungs. Your airways can become constricted when you encounter certain triggers, making it difficult to breathe.

While the exact cause of asthma isn’t known, several risk factors may contribute to its development, including a combination of genetic and environmental factors.

Triggers such as airborne irritants and allergens may increase inflammation and cause airway constriction. Understanding your triggers is essential to managing asthma. You may also need ongoing treatments to help prevent asthma attacks.

Regardless of the possible causes of your asthma, you should consult a healthcare professional if you’re experiencing symptoms such as wheezing, coughing, and shortness of breath. They can help you assess the severity of your asthma, identify and manage your triggers, and come up with an asthma action plan for long-term management.