Definition: An allergen is a substance that triggers—or sets off—an allergic immune response in your body. In a sense, your body sees the substance as foreign and begins to attack it as a foreign invader. This immune reaction can cause symptoms like runny nose, itchy watery eyes, sore throat, dry skin, and irritation of the airways causing wheezing, chest tightness, shortness of breath, and chronic cough.
Pronunciation: AL-lur-JEN
Examples:
dust mites,
second hand smoke,
animal dander,
mold
