What are the causes and risk factors of asthma?
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Dr. Nisarg A. Changawala, MD
Pulmonary Disease Specialist

An increase in pollution and popularity of smoking have increased asthma rates. Watch Nisarg Changawala, MD, from Southern Hills Hospital & Medical Center, explain.

Dr. Harish H. Murthy, MD
Pulmonary Disease Specialist

Pulmonologist Harish Murthy, MD, of Good Samaritan Hospital, says pollution, pollen and an early lack of exposure to allergens could be behind higher asthma rates. Learn more in this video

UCLA Health
Administration Specialist

Many infants and toddlers experience occasional episodes of wheezing caused by respiratory tract infections, but that doesn’t mean they suffer from asthma, a chronic disorder that causes swelling and inflammation of the airways.

Risk factors, including a family history of parental or sibling asthma, eczema and food allergies, can increase a child’s risk to develop asthma. About 60 percent of children with asthma will outgrow it by adulthood. However, only 5 to 30 percent of children with severe asthma will outgrow their asthma by adulthood.

Dr. Paul M. Ehrlich, MD
Allergist & Immunologist

Dr. Anthony Gagliardi, a pulmonologist at St. Vincent's Hospital in New York, says that the study of asthma "is the study of one." That is, asthma describes a set of symptoms—also known as "asthma syndrome,"—that may be triggered by many allergic or environmental causes, or bacterial infection. We have to solve the mysteries, and treat them, one at a time. Although no single "asthma gene" has been discovered, asthma does seem to run in families. Asthma also tends to occur more often in families that have a history of other allergies, and in fact, many patients have both asthma and allergies of the nose, eyes or skin.

If a parent or sibling has asthma, there is greater likelihood of early onset asthma, which means it develops early in childhood. If the parents smoke, particularly the mother, it increases the incidence of asthma at a young age. Still, asthma may start at any age. Attacks are triggered by substances to which children are allergic. For example, a patient with cat allergy develops an asthma attack when he visits a home with cats.

Asthma Allergies Children: A Parent's Guide

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Asthma Allergies Children: A Parent's Guide

Asthma and allergies are at epidemic proportions. It doesn't have to be that way. Two experienced pediatric allergists tell everything a conscientious parent needs to know about these conditions,...
Dr. Sam Pejham, MD
Pediatrician

People with Asthma have very sensitive airways that respond to different triggers. These triggers cause the airways to become inflamed and become narrowed causing the asthma symptoms. The reason why some people get asthma and some don't is still largely unknown, but genetics, lung infections and environmental factors have been linked to cause asthma in some individuals.

Triggers for asthma include: air pollution, smoking, pollen, respiratory infections, allergies, exercise and weather changes.

NewYork-Presbyterian Hospital
Administration Specialist

The exact cause of asthma is unknown, but researchers believe that a combination of factors including genetics and environmental exposures together cause this condition. Typically, asthma begins in childhood, but it can start at any age. People with a family history of asthma or who have allergies are at increased risk for asthma. In people with allergies, the allergic response can make you more sensitive to allergens in the air (such as dust mites, cockroaches, pet dander, tobacco smoke) and can trigger an asthma attack.

Sigma Nursing
Administration Specialist

Doctors aren't sure what causes asthma, but it probably comes from a combination of inherited and environmental triggers. If you are genetically prone to asthma, an attack can be brought on if you feel stressed, breathe cold air or cigarette smoke, have a cold or inhale allergens like mold or pollen.

Asthma can also be caused by allergies. Allergens such as pet dander can swell the passages in the nose and the airways to the lungs, causing tightness of breath and wheezing. Additionally, some people may develop asthma if they are exposed to certain chemicals while at work.

Another possible cause of asthma is the "hygiene hypothesis." Some scientists think that modern advancements in personal hygiene have limited children's exposure to common infections, affecting the development of their immune systems. They may be more prone to developing allergies and asthma because they have not had the chance to develop immunity to common allergens.

Intermountain Registered Dietitians
Nutrition & Dietetics Specialist

Although anyone can get asthma at any age, studies have shown the following trends:

  • Asthma often starts in childhood, and is more common in children than in adults. Still, asthma affects people of all ages—and studies show an increasing number of asthma cases in older people.
  • More boys than girls have asthma—but in adulthood, more women than men have asthma.
  • People who have allergies—or whose family members have allergies—are more likely than other people to have asthma.
  • Asthma tends to run in families. If your mother, father or siblings have asthma, you’re at an increased risk for the disease.
  • People who smoke—or who are around a lot of secondhand smoke—are also more likely to get asthma.
Dr. Mehmet Oz, MD
Cardiologist (Heart Specialist)

Asthma is a complex disease in that it can be caused by a mix of factors, including environment (like dust mites, house dander), lifestyle (where you live dictates toxin levels) and genetics (kids have at least a 25 percent of developing asthma if their parents have allergies).

But it's important to note that even if you have a genetic disposition for asthma, you can control the symptoms and the disabling effects that come from the chronic inflammation secondary to acute attacks.

YOU: The Owner's Manual, Updated and Expanded Edition: An Insider's Guide to the Body that Will Make You Healthier and Younger

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Here are some risk factors that make a person more likely to have asthma:

Gender:

  • Women are more likely to have asthma than men.
  • In children, boys are more likely to have asthma than girls.

Age:

  • Adults ages 18 to 24 are more likely to have asthma than older adults.

Race and ethnicity:

  • Multi-race and black adults are more likely to have asthma than white adults.
  • Black children are two times more likely to have asthma than white children.

Education level:

  • Adults who didn’t finish high school are more likely to have asthma than adults who graduated high school or college.

Income level:

  • Adults with an annual household income of $75,000 or less are more likely to have asthma than adults with higher incomes.

Behavioral risk factors:

  • Smokers are more likely to have asthma than nonsmokers.
  • Obese adults are most likely to have asthma.

The presence of the CDC logo and CDC content on this page should not be construed to imply endorsement by the U.S. government of any commercial products or services, or to replace the advice of a medical professional. The mark “CDC” is licensed under authority of the PHS.

There are a number of theories as to why the rate of asthma is on the rise. One of the most commonly cited reasons is that we are becoming a more "sterile" society and, as such, are not being exposed to as many allergens early in our lives. Therefore, instead of developing tolerance to certain allergens we become sensitized to them. This sensitivity can, in turn, increase rates of asthma.

Asthma is hereditary: If parents have asthma, their children are more likely to suffer from asthma. In this video, I will explain how things like exposure to second-hand smoke and some viral illnesses may make kids more prone to wheezing.

Continue Learning about Asthma Causes

Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.