An allergy starts when the immune system mistakes a normally harmless substance for a dangerous invader. The immune system then produces antibodies that are always on the alert for that particular allergen. When you're exposed to the allergen again in the future, these antibodies can release a number of immune system chemicals, such as histamine, that cause allergy symptoms.

Common allergy triggers include:

  • Airborne allergens, such as pollen, animal dander, dust mites and mold
  • Certain foods, particularly peanuts, tree nuts, wheat, soy, fish, shellfish, eggs and milk
  • Insect stings, such as bee stings or wasp stings
  • Medications, particularly penicillin or penicillin-based antibiotics
  • Latex or other substances you touch, which can cause allergic skin reactions
Jan. 29, 2013