Common Things That Can Cause or Trigger Asthma

You're probably familiar with some of the many triggers of acute asthma attacks with their alarming symptoms of wheezing, coughing, and shortness of breath. Such triggers can include anything from pollen to exercise to stress and more. But asthma triggers are different from actual causes of asthma.

Scientists are still teasing out exactly what those causes are. But here's what we know so far about what can cause asthma to develop—and what you might be able to do about it.

Genetics

Many diseases are caused by a combination of genetic and environmental factors, and asthma is no exception. By some estimates, 50% or more of asthma cases stem from the genes you inherit.

"We have definitely found genetic traits," says Traci Gonzales, a spokesperson for the American Lung Association and a nurse practitioner with UTHealth McGovern Medical School Houston. "If parents have asthma, their kids are more likely to have it."

You're also more likely to develop asthma if you have family members with allergies. (A genetic predisposition to develop asthma and other allergic conditions is called atopy.)

Researchers have already identified dozens of genes that may be involved, and there are likely many more. Some have to do with your body's immune system and others with how your airways function. But genes alone probably aren't enough to cause asthma. More likely, it's a combination of inheriting the right (or wrong) genes, which must then be activated by an environmental trigger.

Allergies

Sometimes asthma triggers and causes can overlap. Many cases of adult-onset asthma are caused by allergy-like dust mites or mold.

Although you can't predict which allergy might cause asthma to develop (you may not even know you have an allergy), you can control symptoms by avoiding your triggers. If you don't already know what these are, an allergist can help you identify your specific allergens.

Respiratory Infections

Infections, particularly respiratory infections, can cause asthma, especially in young children.

"Children's immune systems are still developing and changes [from an infection] can, unfortunately, trigger long-term outcomes in little ones," Gonzales says.

The most common culprits are respiratory syncytial virus (RSV) and parainfluenza, both of which can cause cold-like symptoms, says Gonzales.

Viral and other infections aren't entirely preventable, but you can do your part by getting the appropriate vaccinations (like for the seasonal flu) and washing your hands, says Gonzales.

Air Pollution and Smoke

Not all experts agree, but there is evidence to suggest that both air pollution and secondhand smoke may cause asthma to develop in people who don't already have the condition.

In particular, there is compelling research supporting the idea that exposure to cigarette smoke in childhood (or before you are born through your mother) may be involved in asthma. This could be both indirect (by making a child susceptible to infections that then increase the risk of asthma) or direct (by affecting the immune system or development of the respiratory system).

"We are seeing a trend with exposure to smoking," says Gonzales, "but we don't know if we have exactly [figured out] the mechanism. It could be secondhand or in utero exposure, or smokers themselves having a higher incidence of asthma."

Cigarette smoking itself doesn't seem to cause adult-onset asthma, but it will certainly aggravate symptoms of existing asthma.

Your Job

Occupational asthma is caused by exposure to irritants—like fumes, dust, or gases—on the job. Certain occupations, such as baking, farming, and chemical or plastic manufacturing, may pose a higher-than-average risk. Some people may develop asthma as soon as they're exposed to a toxin on the job, but it's more likely after chronic exposure, says Gonzales.

Obesity

Add asthma to the long list of health conditions caused or exacerbated by obesity. According to the American Lung Association, people who are obese (with a body mass index of 30 or more) have a higher rate of asthma—11% versus only 7% of adults with a healthy BMI. The connection is even stronger for women: Almost 15% of obese women suffer from asthma.

No one knows exactly why this is the case. But being overweight is associated with inflammation in many parts of the body. This inflammation may play a role in asthma. People who are obese also tend to have a harder time controlling asthma symptoms.

"We're seeing this in adults especially but, unfortunately, also in kids," says Gonzales. "That's definitely one you can strive to avoid with exercise and healthy eating."

Hormones

More women than men have asthma, according to the CDC, and some of this may have to do with hormones. Experts have noticed a correlation between the onset of asthma and changing levels of hormones like estrogen. More research is needed to understand why that might be.

Some women or girls with asthma also notice a change in symptoms during puberty, before or during their period, during or right after pregnancy, and before or after menopause.