Allergies are relatively common. Both genetics and environmental factors play a role.
The immune system normally protects the body against harmful substances, such as bacteria and viruses. It also reacts to foreign substances called allergens, which are generally harmless and in most people do not cause a problem.
But in a person with allergies, the immune response is oversensitive. When it recognizes an allergen, it releases chemicals such as histamines. which fight off the allergen. This causes itching, swelling, mucus production, muscle spasms, hives, rashes, and other symptoms, which vary from person to person.
Common allergens include pollen, mold, pet dander, and dust. Food and drug allergies are common. Allergic reactions can also be caused by insect bites, jewelry, cosmetics, spices, and other substances.
Some people have allergy-like reactions to hot or cold temperatures, sunlight, or other environmental triggers. Sometimes, friction (rubbing or roughly stroking the skin) will cause symptoms.
A specific allergy is not usually passed down through families (inherited). However, if both your parents have allergies, you are likely to have allergies.
Allergy to mold - animal dander - dust (4 images)(Doctor-Reviewed information)
Allergy-related symptoms can occur after you are around mold, certain animals or animal hair, dust, and other substances. These substances are usually found indoors and do not cause symptoms for most people. See also: Asthma; Allergic rhinitis.Reviewer: Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Date: 05/25/2009
Anaphylaxis (8 images)
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(Doctor-Reviewed information)
Anaphylaxis is a life-threatening type of allergic reaction.Reviewer: David C. Dugdale, III., MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 04/28/2008
Allergic rhinitis (3 images)
Average Rating:
(Doctor-Reviewed information)
Allergic rhinitis is a collection of symptoms, mostly in the nose and eyes, which occur when you breathe in something you are allergic to, such as dust, dander, or pollen. This article focuses on allergic rhinitis due to outdoor triggers, such as ...Reviewer: A.D.A.M. Editorial Team: David Zieve, MD, MHA, Greg Juhn, MTPW, David R. Eltz. Previously reviewed by Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School (5/25/2009). Date: 11/15/2009
Food allergy (6 images)(Doctor-Reviewed information)
A food allergy is an exaggerated immune response triggered by eggs, peanuts, milk, or some other specific food.Reviewer: Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Date: 04/23/2009
Hives (10 images)(Doctor-Reviewed information)
Hives are raised, often itchy, red welts on the surface of the skin. They are usually an allergic reaction to food or medicine.Reviewer: Kevin Berman, MD, PhD, Associate, Atlanta Center for Dermatologic Disease, Atlanta, GA. Review provided by VeriMed Healthcare Network.Date: 04/15/2009
Allergic reactions (10 images)(Doctor-Reviewed information)
Allergic reactions are sensitivities to substances, called allergens, that are contacted through the skin, inhaled into the lungs, swallowed, or injected.Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 04/28/2008
Drug allergies (11 images)(Doctor-Reviewed information)
Drug allergies are a group of symptoms caused by allergic reaction to a drug (medication.Reviewer: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.Date: 08/06/2008
Allergy testing (4 images)(Doctor-Reviewed information)
Allergy tests are any of several tests used to determine the substances to which a person is allergic.Reviewer: Stuart I. Henochowicz, MD, FACP, Associate Clinical Professor of Medicine, Division of Allergy, Immunology, and Rheumatology, Georgetown University Medical School. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc. Date: 05/25/2009
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