Table of Contents
- Allergy facts
- Allergy overview
- What is an allergy?
- What is an allergy? (Continued)
- What causes allergies?
- What causes allergies? (Continued)
- Who is at risk for allergies and why?
- What are common allergic conditions, and what are allergy symptoms and signs?
- Allergic rhinitis (hay fever)
- Allergic eyes (conjunctivitis)
- Eczema (atopic dermatitis)
- Hives (urticaria)
- Where are allergens?
- In the Air We Breathe
- In What We Ingest
- Touching Our Skin
- Injected Into Our Body
Quick GuideAllergy: What Happens in a Nasal Allergy Attack
What is an allergy?
An allergy refers to an exaggerated reaction by the immune system in response to exposure to certain foreign substances. The response is exaggerated because these foreign substances are normally seen by the body as harmless in nonallergic individuals and do not cause a response in them. In allergic individuals, the body recognizes the foreign substance, and the allergic part of the immune system generates a response.
Allergy-producing substances are called "allergens." Examples of allergens include pollens, dust mites, molds, animal proteins, foods, and medications. When an allergic individual comes in contact with an allergen, the immune system mounts a response through the IgE antibody. People who are prone to allergies are said to be allergic or "atopic."
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American College of Allergy, Asthma, & Immunology. Food allergy: a practice parameter. Ann Allergy Asthma Immunol. 2006 Mar;96(3 Suppl 2):S1-68. No abstract available.
Flinterman AE, Pasmans SG, Hoekstra MO, Meijer Y, van Hoffen E, Knol EF, Hefle SL, Bruijnzeel-Koomen CA, Knulst AC. Determination of no-observed-adverse-effect levels and eliciting doses in a representative group of peanut-sensitized children. J Allergy Clin Immunol. 2006 Feb;117(2):448-54.
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Medically Reviewed By: Ellen Reich, MD, Board Certified in Allergy and Immunology, Board Certified in Pediatrics and Michael Manning, MD, of the American Board of Allergy and Immunology.
6.iStock, Color Atlas of Pediatric Dermatology Samuel Weinberg, Neil S. Prose, Leonard Kristal Copyright 2008, 1998, 1990, 1975, by the McGraw-Hill Companies, Inc. All rights reserved.
7.Charles Daghlian, Getty Images/ScienceFoto, iStock
11.Dartmouth Electron Microscope Facility, Dartmouth College
17.iStock, Getty Images, iStock
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