Allergens most often trigger asthma symptoms by entering the lungs as you breathe. Pollens, molds, animal dander, and dust mite or cockroach particles are allergens that can be in the air. Not as often, someone with allergies develops asthma symptoms when an allergen is swallowed. In a small number of allergic people, eating certain foods, such as eggs or shellfish, may trigger asthma. Other people are allergic to certain food additives, preservatives or medications.
Some allergies are easy to identify.
For example, if you have asthma symptoms every time you are around a cat, you are probably allergic to cats. If your asthma gets worse every spring, you probably are allergic to the pollen of some tree, grass, weed, or flower that blooms during this season. Other allergies are hard to identify. You could be allergic to something that is around all the time, such as house dust, and be unaware that it is causing or increasing your asthma symptoms. Your physician will ask detailed questions about your symptoms and the possible allergy triggers in and around your home, school, or workplace to determine whether you have allergies.