Asthma in Teens and Adults

The cause of asthma isn't known. Health experts believe that inherited, environmental, and Reference immune system Opens New Window factors combine to cause Reference inflammation Opens New Window Reference Opens New Window of the airways. This can lead to asthma and asthma attacks.

Family history

Asthma may run in families (be inherited). If this is the case in your family, you may be more likely than other people to get long-lasting (chronic) inflammation in the airways.

Immune system

In some people, an Reference allergic reaction Opens New Window causes asthma symptoms. An Reference allergen Opens New Window makes the immune system cells release chemicals that cause inflammation.

Studies show that exposure to allergens such as Reference dust mites Opens New Window, cockroaches, and Reference animal dander Opens New Window may influence asthma's development.^{Reference 1} Asthma is much more common in people with allergies, although not all those who have allergies get asthma. And not all people with asthma have allergies.

Environment

Environmental factors and today's germ-conscious lifestyle may play a role in the development of asthma. Some experts believe that there are more cases of asthma because of pollution and less exposure to certain types of bacteria or infections.^{Reference 2} As a result, children's immune systems may develop in a way that makes it more likely they will also get allergies and asthma.

Asthma in adults also can be related to work. This is called Reference occupational asthma.

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