May 25, 2017

Allergy (Allergies)

Allergy facts

  • Allergy involves an exaggerated response of the immune system, often to common substances such as foods or pollen.
  • The immune system is a complex system that normally defends the body against foreign invaders, such as bacteria and viruses, while also surveying for abnormal changes in an individual’s own cells, such as cancer.
  • Allergens are substances that are foreign to the body and that cause an allergic reaction.
  • IgE is the allergic antibody.
  • Although many individuals outgrow allergies over time, allergies can also develop at any age, including during adulthood.
  • While the environment plays a role in the development of allergy, there is a greater risk of developing allergic conditions if a person has a family history of allergy, especially in parents or siblings.

Allergy overview

This is a review regarding how the allergic response of the immune system occurs and why certain people become allergic. The most common allergic diseases are described, including allergic rhinitis (nasal allergies), allergic conjunctivitis (eye allergies), allergic asthma, urticaria (hives), and food allergies.

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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Reviewed on 1/13/2017