Asthma:
Causes and Triggers

Intro	Treatment
Common Symptoms	When to Get Help
Causes and Triggers	Asthma Action Plan
Dealing with Triggers	Living with Asthma
Exercise Induced Asthma	Resources
Getting Diagnosed

What causes asthma?

No one knows for sure what causes asthma, but doctors have found that certain things in the environment can irritate a person’s breathing and cause symptoms. Asthma runs in families, and teens who are overweight are more likely to have asthma. Most teens who are diagnosed with asthma have allergies that can aggravate their breathing.

What are triggers?

Triggers are things in the environment that bring on asthma symptoms or “asthma flare-ups” (sometimes called asthma attacks). People who do not have asthma are not sensitive to these triggers. Some triggers such as pollen will only affect people with asthma during certain seasons and not throughout the year. Others may have symptoms only when they are around a cat, for example.

The following categories and list of “triggers” can cause asthma symptoms for some people.

Allergens: things that you are sensitive to that cause a type of allergic reaction

• Dust mites
• Animal dander – (which is from skin, fur or feathers of animals)
• Cockroach and rodent droppings
• Pollen from trees, grasses and weeds
• Mold and mildew

Irritants: (smells and other things that you might breathe in through your nose, mouth and into your lungs)

• Cigarette smoke – both smoke from your own cigarette or someone else’s
• Strong smells - perfumes, make up, cleaning products, scented candles, fresh paint, gasoline
• Chalk dust, wood smoke
• Air pollutants-smog, diesel fuel and factory emissions

Weather

• Cold air
• Hot temperatures, humidity or “sticky weather”

Exercise

• Sports and other physical activities (such as running) that cause sudden and rapid breathing

Viral infections

• Colds and flu or other infections of the nose, throat, lungs, etc. that can cause coughing, sore throat, and/or trouble breathing

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Written by the CYWH Staff at Children's Hospital Boston

Updated: 9/4/2009