What causes Allergen?
Last updated September 7, 2026.
**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.
What to do
- **Track your symptoms:** Write down what you ate, touched, or breathed in before symptoms started.
- **Reduce exposure:** Limit contact with known triggers and keep windows closed when pollen counts are high.
- **Check food labels:** If you have a food allergy, check ingredients every time you buy a product.
- **Get evaluated:** Ask a clinician about recurring symptoms and whether allergy testing would help.
- **Act on severe symptoms:** For sudden throat swelling or trouble breathing, use prescribed epinephrine immediately and call 911.
Related questions
- Can i see what my doctor wrote about me
- How do i find out what my insurance covers
- What age should i start mammograms
- What are clots in period blood