**An allergen is a substance, such as pollen or a food protein, that triggers an allergic reaction when your immune system treats it as harmful.**
An allergen is a trigger, not a disease you develop. Common sources include pollen, dust mites, mold, pets, foods, medicines, and insect venom. Your genes and environment influence whether you develop an allergy, and exposure alone does not mean you will react. Track when your symptoms occur and reduce contact with known triggers. See a clinician if symptoms recur or the cause is unclear.
Tracking down your allergen
Common questions
What causes Allergen?
An allergen is a substance that causes an allergic reaction, not a condition with its own cause. Pollen, dust mites, mold, pet dander, foods, medicines, and insect venom are common triggers. If you are allergic, your immune system reacts to the substance and releases chemicals that cause symptoms such as sneezing, itching, or hives. Your genes and environment affect your risk. Record symptoms and exposures, and see a clinician for recurring reactions or an unclear trigger. For sudden throat swelling or trouble breathing, use prescribed epinephrine immediately and call 911.