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Definition

By Mayo Clinic staff

Allergies occur when your immune system reacts to a foreign substance such as pollen, bee venom or pet dander.

Your immune system produces substances known as antibodies. Some of these antibodies protect you from unwanted invaders that could make you sick or cause an infection. When you have allergies, your immune system makes antibodies that identify your particular allergen as something harmful, even though it isn't. When you come into contact with the allergen, your immune system's reaction inflames your skin, sinuses, airways or digestive system.

The severity of allergies varies from person to person and can range from minor irritation to anaphylaxis — a potentially life-threatening emergency. While allergies can't be cured, a number of treatments can help relieve your allergy symptoms.

References
  1. Frequently asked questions. American College of Allergy, Asthma & Immunology. http://www.acaai.org/patients/faq/Pages/default.aspx. Accessed Nov. 3, 2010.
  2. Tips to remember: What is an allergic reaction? American Academy of Allergy, Asthma & Immunology. http://www.aaaai.org/patients/publicedmat/tips/whatisallergicreaction.stm. Accessed Nov. 3, 2010.
  3. Wayt TM. Anaphylaxis. In: Ferri FF. Ferri's Clinical Advisor 2011: Instant Diagnosis and Treatment. Philadelphia, Pa.: Mosby Elsevier; 2011. http://www.mdconsult.com/books/page.do?sid=1079270789&eid=4-u1.0-B978-0-323-05610-6..00010-X--sc0170&isbn=978-0-323-05610-6&type=bookPage§ionEid=4-u1.0-B978-0-323-05610-6..00010-X--sc0170&uniqId=225503130-3.  Accessed Nov. 3, 2010.
  4. Atkins D, et al. Diagnosis of allergic disease. In: Kliegman RM, et al. Nelson Textbook of Pediatrics. 18th ed. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/224902915-6/0/1608/434.html?tocnode=54478103&fromURL=434.html#4-u1.0-B978-1-4160-2450-7..50142-0_3366. Accessed Nov. 3, 2010.
  5. Tips to remember: Allergy shots. American Academy of Allergy, Asthma & Immunology. http://www.aaaai.org/patients/publicedmat/tips/whatareallergyshots.stm. Accessed Nov. 3, 2010. Accessed Nov. 3, 2010.
  6. Tips to remember: Asthma and allergy medications. American Academy of Allergy, Asthma & Immunology. http://www.aaaai.org/patients/publicedmat/tips/asthmaallergymedications.stm. Accessed Nov. 3, 2010.
  7. Allergy. Mitchell G, et al. In: Rakel RE. Rakel: Textbook of Family Medicine. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/225194068-12/1078164908/1481/288.html#4-u1.0-B978-1-4160-2467-5..50028-2--cesec19_1317. Accessed Nov. 3, 2010.
  8. Engler RJ, et al. Complementary and alternative medicine for the allergist-immunologist: Where do I start? The Journal of Allergy and Clinical Immunology. 2009;123:309.
  9. DeShazo RD, et al. Pharmacotherapy of allergic rhinitis. http://www.uptodate.com/home/index.html. Accessed Nov. 3, 2010.
  10. Li JT (expert opinion). Mayo Clinic, Rochester, Minn. Nov. 16, 2010.
  11. Naegleria FAQs. Centers for Disease Control and Prevention. http://www.cdc.gov/parasites/naegleria/faqs.html. Accessed Dec. 30, 2011.
DS01118 Jan. 20, 2012

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