An allergen is a substance that can cause an allergic reaction. In some people, the immune system thinks allergens are foreign or dangerous. This is what leads to allergy symptoms.
Common allergens include:
- Animal proteins and animal dander
- Bacteria and viruses
- Drugs (such as antibiotics or medications you put on your skin)
- Foods (such as milk, chocolate, strawberries, wheat)
Wasserman SI. Approach to the patient with allergic or immunologic disease. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 257.