Find Out What Causes Asthma

Find Out What Causes Asthma

Most people with asthma understand asthma triggers, but what causes asthma in the first place?

Asthma occurs when certain cells of the body's immune system misidentify substances as very harmful and overreact to them, causing the bronchial tubes in the lungs to become inflamed and narrowed. What causes asthma—and why it occurs in some people and not others—has long baffled medical experts. Still, a growing number of risk factors and asthma triggers have been identified, helping doctors to diagnose and treat people affected by the disease.

How do people get asthma?
Here are 10 risk factors to assess your likelihood of developing asthma.

1. You're overweight.
You know obesity can increase your risk for arthritis, diabetes, stroke, and other health conditions, but did you know you can add asthma to that list as well? It's true (although it's not entirely clear why). It could be that excess weight presses on the lungs, triggering responses typical of asthma. It might also be that when someone is overweight, all their organs have to work harder, including their lungs.

2. You have skin allergies.
Although skin allergies may not be what causes asthma, studies show that there is a correlation between skin allergies and asthma. In fact, children who have eczema and hay fever are nine times more likely to develop asthma as adults, and can later have asthma more severe and persistent.

3. You have nasal allergies.
People who suffer from nasal allergies are likely to develop asthma. It makes sense. The nose and lower airways are part of the same respiratory system, and they can react the same way as the lungs do to allergens, irritants, and viruses.

4. You have eye allergies.
Like the mucus membranes in your nose and airways, the membranes in your eyes can be sensitive to allergens. "Once you have one allergy -- skin, food, nose, eyes -- you're at greater risk for developing other allergies and, in this case, asthma," says Neil L. Kao, MD, of the Allergic Disease and Asthma Center in Greenville and Spartansburg, S.C., and a fellow in the American Academy of Allergy, Asthma and Immunology (AAAI).

5. Your mom or dad has asthma.
Your chances of developing asthma increase significantly when asthma runs in your family. Right now, there's nothing to be done about genetic risk, but doctors are hard at work to identify which genes are the culprits.

6. You're a boy.
"Asthma occurs at all ages of life," Kao says. However, the likelihood of having it does depends on age and gender. Before puberty, asthma is more common in males.

7. You're a young woman.
After adolescence, asthma is more prevalent in women than in men. But the battle of the sexes evens out with time. "After about 50ish, occurrence is about even in men and women," Kao says. Still, women tend to have more severe symptoms than men, and they're at greater risk for deadly asthma (possibly because of monthly hormonal fluctuations). 

8. You're pregnant.
Weight gain is a natural and healthy part of pregnancy, but it can mean hard work for your lungs: the baby pressing on the diaphragm, the extra pounds the lungs must support, and the growing fetus for which the lungs must now also breathe, according to Kao.

9. You have hyperactive airways.
Some children have hyperactive airways. Their bronchial airways just over-respond to various stimuli by becoming inflamed and narrow. It's a similar condition to asthma, and having hyperactive airways puts people at greater risk for developing asthma as adults.

10. You're no stranger to tobacco smoke.
Children who grow up around smokers are more likely to develop asthma than kids whose parents don't smoke. Be it first- or second-hand, cigarette smoke can stimulate the production of mucus in the lungs -- another part of the asthma response that makes it difficult to breath. In fact, any kind of smoke can cause problems. "It doesn't matter whether it's smoke from a cigarette or a pipe or even a burning building," Kao says. "Smoke is made up of chemicals and particulate matter that can irritate your lungs."

Multiplication matters
The more risk factors you have, the more likely you are to develop asthma. If you have any of these risk factors and experience symptoms like coughing, wheezing, chest tightness, shortness of breath, or excess mucus or phlegm, talk to your doctor. Even if you don't have asthma symptoms, your doctor may be able to suggest strategies for lowering your risk of an asthma attack.

Medically reviewed in May 2018.

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