Medically Reviewed

Asthma Causes

Struggling to breathe is no joke. Here’s what the experts say is behind this concerning condition.

Updated Jun 14, 2021

By

Stephanie Wood

Medical ReviewerKatie Marks-Cogan, M.D.

Our Experts: Albert J. Polito, M.D.; Reynold Panettieri, M.D.; David R. Stukus, M.D.

Albert J. Polito, M.D.Chief of the Division of Pulmonary Medicine and Medical Director The Lung Center at Mercy Medical Center Baltimore, MD

Reynold Panettieri, M.D.Pulmonologist and Professor of Medicine Rutgers University New Brunswick, NJ

David R. Stukus, M.D.Associate Professor of Pediatrics in the Division of Allergy and Immunology Nationwide Children’s Hospital Columbus, OH

Let’s just get this out of the way right now: There is no easy answer to what caused you to get asthma. You might be able to point a finger at your parents if one or both of them have it, because there’s clearly a genetic connection. But that’s only one piece of the puzzle. As for what triggers the symptoms themselves, that list is long (see: pets, perfume, exercise, pollen, and cleaning products, to name a few). Fortunately, not everyone reacts to every trigger, but it’s critical to asthma control to get a handle on yours. Let’s take a closer look.

Asthma is a chronic condition that affects your bronchial tubes, the airways in your lungs. If you have asthma, your airways are always inflamed, causing excess mucus production and swelling, both of which narrow the passageway that air has to travel through. In turn, you’re left feeling short of breath, wheezy, and probably coughing a lot. Asthma is one of the most common, and costly, chronic illnesses in the U.S. More than 25 million people in the U.S. have it, including over 5 million children under 18, according to the Centers for Disease Control and Prevention (CDC). That translates to one in 13 people in the U.S. currently living with asthma.

Asthma can occur at any age, but most cases are diagnosed in childhood. Not everyone who has asthma experiences it in the same way: Some people only have mild and occasional symptoms, while about 5% to 10% of asthmatics have it more severe—to the extent that it impacts everyday life and causes serious attacks. There is no cure for asthma, but with the right treatment, it’s very possible to keep it well-controlled so you can keep living your life.

The roots of this chronic condition are a million-dollar question—one science has yet to come up with the full answer for. There are clues as to who might be at greater risk for it: namely, children of parents with asthma and children with a family history of allergies, which often accompany asthma. Some research has found that genetic factors account for as much as 70% of a person’s risk of having asthma.

Childhood Asthma

Asthma that develops in childhood—which happens in the majority of cases—is more likely to have a genetic link, while adult-onset asthma is thought to be less related to genetics. That said, people with no family history may still develop asthma, and those with a family history may never get it.

Genetics are only part of the picture, however. Other childhood experiences or events can also increase risk, including:

• A severe respiratory infection. Infections like respiratory syncytial virus (RSV) or bronchiolitis cause inflammation and damage to still-developing lung tissue during infancy and early childhood.

• An allergic condition like eczema. It’s been shown that up to one-third of eczema patients—which is usually diagnosed in infancy or early childhood—go on to develop asthma.

• A mother who smoked during pregnancy. Along with an increased risk of childhood asthma, a new study found that people whose mothers smoked during pregnancy are also at increased risk of adult-onset asthma between the ages of 31 and 46.

• Exposure to heavy air pollution. Babies and children have a faster breathing rate and therefore take in more irritants, causing damage to still-developing lung tissue.

Gender and Asthma Risk

Another factor that clearly plays a role in the development of asthma is gender. Before puberty, asthma is more common in boys, affecting 8.4% compared to 5.5% of girls. After puberty, asthma becomes more common in women. Research shows that 9.8% of women have asthma, while only 6.1% of men do. Women are also more likely to have adult-onset and severe asthma than men. All of this points to a hormonal connection, but the mechanism is still unclear. What we do know: Ovarian hormones—estrogen and progesterone—appear to increase airway inflammation. Meanwhile, the male hormone testosterone seems to hinder it by quieting down certain types of immune cells so that they are not as reactive to asthma triggers.

The fluctuations in female hormones, which occur during menstruation, pregnancy, and menopause, also seem to contribute. Women often find that asthma symptoms can start to worsen just before their periods and continue until it ends. In fact, most hospitalizations of women for asthma also occur right before their periods.

Is Race a Risk Factor for Asthma?

Race and ethnic background definitely play a role in who gets asthma. Asthma disproportionately affects minorities in the U.S., with Black, Hispanic, American Indian, and Native Alaskans having the highest asthma rates, hospitalizations, and deaths. Let’s take a closer look at how the numbers break down:

• Black children are three times as likely to have asthma as white children.

• Puerto Ricans have a higher rate of asthma prevalence than any other racial or ethnic group in the U.S.

• Indigenous Americans are nearly two times as likely to experience asthma symptoms every day compared to other adults with asthma.

• Black women have the highest rates of death due to asthma.

The reasons for race being a risk factor in asthma are not a mystery: lower socioeconomic status, less education, limited access to healthcare, and poor urban air quality, to name a few, are the driving variables in this equation.

While most people—health care providers and patients alike—use the umbrella term asthma, it’s not a one-size-fits-all disease. There are multiple types of asthma, and each type has different triggers—events or things in the environment that can set off an asthma attack. The most common types include:

Allergic Asthma

If your asthma symptoms are triggered by an allergic reaction, this is called allergy-induced, or allergic, asthma. Allergic asthma is very common and the type most likely to affect children. Inhaled allergens that may trigger your asthma include:

• Dust mites

• Pollen

• Pet dander

There are a few less-common allergens that can cause an asthmatic reaction as well. Although rarer, when an asthma attack does occur as a result of one of these triggers it may be more serious. They include:

• Cockroaches

• Eggs

• Milk

• Peanuts

• Shellfish

• Tree nuts

• Wheat

Non-Allergic Asthma

Someone with this type of asthma doesn’t have allergic triggers, but they do react to a variety of other environmental factors or everyday items they come in contact with, including:

• Food additives, such as MSG and food coloring

• Irritants in the air, like smog, ozone, paint fumes, gasoline, charcoal grills, tobacco smoke

• Medications, including aspirin, nonsteroidal anti-inflammatories (NSAIDs), and beta blockers

• Stress and strong emotions, such as anger, fear, or excitement

• Viral respiratory infections like the cold or flu

• Weather conditions, like dry wind, thunderstorms, cold air

Exercise-Induced Asthma

Ironically, the very thing you do to improve your lung capacity is the same thing that may temporarily mess with your breathing. Exercise, especially when done in cold air, can exacerbate inflammation and increase asthma symptoms. This doesn’t mean you can’t work out or play sports, however. With proper treatment and good asthma control, you should be able to continue any physical activity you enjoy.

Occupational Asthma

People who work in certain fields may develop asthma symptoms due to triggers in their workplace. These triggers include chemicals used in manufacturing; dusts from wood, grain, or flour; some mold, animals, and insects; cleaning products; and latex gloves. Workers in these fields are at higher risk:

• Bakers

• Detergent manufacturers

• Farmers

• Grain elevator workers

• Laboratory workers (especially those who work with animals)

• Metal workers

• Millers

• Plastic workers

• Woodworkers

Adult-Onset Asthma

This category simply refers to anyone who develops asthma as an adult, rather than in childhood when most cases of asthma are diagnosed. It’s not clear why asthma doesn’t appear until later in life: One possibility is that the person with asthma never encountered triggers like certain chemicals until becoming an adult. Or perhaps someone has asthma that’s triggered by a pet allergy, but only discovers this when they get a dog after college. It’s also possible for an upper respiratory infection to develop into asthma. Whatever the underlying cause, adult-onset asthma can be more serious and persistent than other forms, so you want to get checked out at the first signs.

Nocturnal Asthma

This type of asthma has a variety of triggers, but the hallmark is that symptoms are especially bad at night, robbing patients of sleep. If you find yourself waking up in the middle of the night because of coughing and wheezing, or shortness of breath—or if falling asleep is a challenge because of your rapid breathing—talk with your doctor about nocturnal asthma.

You probably noticed that there is some overlap in these categories. That’s because it’s possible to share triggers with another type of asthma, and also because you can have more than one type of asthma. For instance, you could have non-allergic asthma and exercise-induced asthma. Or you could have allergic and nocturnal asthma. What’s most important is knowing your individual triggers, so you can avoid them and keep your asthma under control.