What are the symptoms of Allergen?
Last updated September 7, 2026.
**If you are allergic, an allergen can trigger sneezing, a runny nose, itching, hives, swelling, or wheezing.** An allergen is a substance that triggers an allergic reaction, such as pollen, pet dander, or certain foods. Your symptoms depend on the trigger and whether you breathe it in, swallow it, or touch it. Some reactions also cause stomach cramps, vomiting, or diarrhea. Avoid known triggers and record when symptoms occur to help your clinician decide whether allergy testing is needed.
What to do
- **Track your symptoms:** Record what you ate, touched, or breathed in before symptoms began.
- **Limit exposure:** Avoid known allergens and do not deliberately expose yourself to test a suspected allergy.
- **Ask about treatment:** Ask your clinician or pharmacist which medicine fits your symptoms and health history.
- **Get evaluated:** See a clinician if reactions recur, the trigger is unclear, or symptoms disrupt your sleep.
- **Recognize an emergency:** For trouble breathing, throat or tongue swelling, or fainting after exposure, use prescribed epinephrine immediately if available and call 911.
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