While some asthma symptoms may appear contagious, it does not spread from person to person. Learn about its causes.

Asthma is a condition that reduces lung function by narrowing and inflaming airways. It’s common, often first appearing in childhood and affecting both children and adults, and about 25 million people overall. In the U.S., 1 in 13 people has been diagnosed with asthma.

Environmental factors like exposure to dust or smoke can trigger asthma attacks in some people. Different triggers can bring on different types of asthma. These include:

  • adult-onset asthma
  • exercise-induced bronchoconstriction (EIB)
  • occupational asthma
  • asthma-COPD overlap
  • nonallergic asthma
  • allergic asthma
  • pediatric asthma

Some asthma symptoms can resemble conditions that are communicable (contagious), such as bronchitis or pneumonia. However, while people with asthma symptoms like a persistent cough may appear ill, asthma does not spread from person to person.

Asthma is not contagious in humans. However, experts have found that asthma tends to run in families. As a result, children of parents with asthma are at an increased risk of developing asthma.

Many potential factors can cause a person to develop asthma or trigger an asthma attack. During an asthma attack, a person may experience severe symptoms like difficulty breathing, a persistent cough, or tightness in the chest.

Different environmental factors like exposure to dust or smoke can trigger or cause sudden asthma attacks in some people. These different triggers can spark different types of asthma, including adult-onset asthma, exercise-induced bronchoconstriction (EIB), occupational asthma, asthma-COPD overlap, nonallergic asthma, allergic asthma, and pediatric asthma.

Causes and risk factors for asthma include the following.

Genetics and epigenetics

Over the past few decades, scientists have established several gene markers that are associated with childhood-onset asthma and atopic asthma.

However, experts also acknowledge that genetics is just one factor in determining a person’s risk for asthma. A developing field of research into epigenetics, or how certain genes you carry can be turned on and off depending on your environment, has found several genes that are linked to developing asthma — and conversely, some genes may be protective against asthma.

Epigenetic change does not change your DNA but instead affects its structure.


Allergies are one of the most common triggers of asthma symptoms. Your body reacts to allergens such as mold, dust mites, pet dander, and pollen by triggering your body’s immune system into action. When your immune system is triggered by an allergen, it can cause swelling in your lung’s airways, making it harder to breathe.

Air quality and environmental factors

Asthma disproportionately affects People of Color, who — due to systemic racism — are most likely to live and work close to dangerous air pollution. This kind of pollution is known to sharply increase a person’s risk of developing asthma.

Climate change

Scientists studying the relationship between human health and the environment have found that the effects of climate change, such as increased snow, rainfall, and flooding, are linked to increased asthma risk.


It appears that female sex hormones may also play a role in a person’s risk of asthma. Asthma rates are most prevalent and severe in women over the age of puberty. Asthma rates are highest in women with early periods and multiple pregnancies, suggesting a female sex hormone component in developing asthma.

When female sex hormones increase, such as during periods and pregnancy, asthma risk may increase. These hormones may increase inflammation in the body, affecting the airways.


Scientists have identified obesity as another likely cause of asthma. It’s unclear how these two conditions are linked, though experts think it has to do with inflammation and reduced lung function caused by excess weight.

Lung infection

Lung infections, such as RSV or Chlamydia pneumoniae (CP), may increase your risk of developing asthma, especially if you got the infection early in life. It appears that childhood lung infections can change the microbial environment of the lungs, making them more likely to experience the inflammation and narrowing of the airways caused by asthma.

Premature birth

Premature birth may cause a baby to develop lung and breathing problems, including asthma. The bodies of premature babies are less developed, and this premature development can cause problems for babies throughout their lives into adulthood.


Exposure to triggers is likely to cause asthma symptoms in people who have asthma. Sometimes these symptoms can be severe. Common triggers for asthma attacks include:

  • acid reflux
  • air pollution, such as factory emissions, car traffic, and wildfire smoke
  • cold, dry air
  • disinfectants and other cleaning products
  • dust mites
  • foods and food additives
  • fragrances
  • infections linked to colds, the flu, and viruses
  • medications
  • mold
  • pests, such as cockroaches and mice
  • pets with fur, such as cats or dogs
  • physical exercise
  • pollen exposure
  • sinus infections
  • strong emotions causing hyperventilation
  • tobacco smoke, including secondhand smoke
  • weather conditions like thunderstorms and high humidity

While there’s no sure way to prevent asthma, you can reduce your chances of developing asthma if you’re at risk of developing it, or help prevent asthma attacks if you already have asthma.

If you already have asthma, most doctors will advise you to develop an asthma-management plan to avoid triggers so as not to experience the worst of your symptoms. A good asthma-management plan has four parts:

  1. Minimize your contact with known triggers.
  2. Take your asthma medications.
  3. Track asthma and recognize early warning signs of an attack.
  4. Make an emergency plan if you require immediate medical attention for your asthma symptoms.

Below are some frequently asked questions about asthma that can clear up questions about how people get it.

Is asthma contagious through kissing?

Asthma is not contagious, through kissing or other means. Kissing can spread other communicable diseases, however, such as mononucleosis, the flu, COVID-19, and other viruses.

Is it safe to be around people who have asthma?

It’s completely safe to be around someone with asthma although they may be shedding viral particles themselves.

However, if the person with asthma is easily triggered into asthma attacks, you should take care to avoid exposing them to their triggers. For example, if a friend with asthma is most commonly triggered by exposure to pet hair, avoid bringing your dog along when visiting them.

Is pneumonia from asthma contagious?

Pneumonia is a contagious short-term disease, unlike asthma. However, people with asthma are more likely to develop pneumonia and other lung-related illnesses compared to people without asthma, due to lung damage. While asthma is not contagious, pneumonia can be and it usually requires antibiotic treatment to overcome.

Is croup from asthma contagious?

People with asthma are at increased risk of illnesses affecting the lungs, including croup in children. The viruses that cause croup are contagious. However, the coughing and noisy breathing caused by croup is not necessarily contagious. Children with croup are considered noncontagious once the fever has passed.

Asthma is a common lung condition with many different potential risks, causes, and triggers. Asthma is not contagious. The symptoms of asthma can make it difficult to breathe and also increase your risk for other lung-related issues. While asthma cannot be prevented, it can be managed by avoiding triggers and following a good asthma-management plan.