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Asthma Causes and Triggers

No one really knows what causes asthma. What we do know is that asthma is a chronic inflammatory disease of the airways. The causes of asthma symptoms can vary for different people. Still, one thing is consistent with asthma: when airways come into contact with an asthma trigger, the airways become inflamed, narrow, and fill with mucus.

When you have an asthma attack, spasms of the muscles around the airways, inflammation and swelling of the mucosal membrane lining the airways, and excessive amounts of mucus contribute to airway narrowing. This makes airway resistance increase and the work of breathing more difficult, causing shortness of breath, cough, and wheezing. You may have coughing with asthma because of the irritation inside the airway and the body's attempt to clean out the accumulations of thick mucus.

So why do you have asthma and your friend doesn't? No one really knows for sure. We do know that allergies play a role in many people with asthma but not in all. As with allergy, you can blame your family history, as there is a strong genetic component for asthma.

If you or a loved one has asthma, it's important to understand the many asthma triggers. Once you identify and reduce exposure to the specific triggers or causes of asthma, you can take an active role in controlling your asthma and reducing the frequency of asthma attacks. For example, if you find that allergies are the cause of your asthma, you may have allergic asthma. Being aware of environmental, food, and inhaled allergies and avoiding them can significantly help in asthma prevention by reducing the frequency or severity of asthma attacks. If environmental pollution seems to cause your asthma, it's important to stay indoors during periods of heavy air pollution. Try to find the specific triggers or causes of your asthma, and then plan to avoid these triggers and have better asthma control.

Here are the most common asthma triggers:

Allergies Can Cause Asthma

Allergies with asthma is a common problem. Eighty percent of people with asthma have allergies to airborne substances such as tree, grass, and weed pollens, mold, animal dander, dust mites, and cockroach particles. In one study, children who had high levels of cockroach droppings in their homes were four times more likely to have childhood asthma than children whose homes had low levels. Asthma exacerbation after dust exposure is usually due to dust mite allergy.

For more detail, see WebMD's Allergies and Asthma.

Food and Food Additives Trigger Asthma

Food allergies can cause mild to severe life-threatening reactions. The most common foods associated with allergic symptoms are:

  • Eggs
  • Cow's milk
  • Peanuts
  • Soy
  • Wheat
  • Fish
  • Shrimp and other shellfish
  • Salads & fresh fruits

Food preservatives can also trigger asthma. Sulfite additives, such as sodium bisulfite, potassium bisulfite, sodium metabisulfite, potassium metabisulfite, and sodium sulfite, are commonly used in food processing or preparation and may trigger asthma in those people who are sensitive.

For more detail, see WebMD's Food Allergies and Asthma.

WebMD Medical Reference

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