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You are here : 3-RX.com > Medical Encyclopedia > Diseases and Conditions > Allergic Reactions
      Category : Health Centers > Allergies

Allergic Reactions

Alternate Names : Acquired Sensitivity Reaction, Induced Sensitivity Reaction

Overview, Causes, & Risk Factors | Symptoms & Signs | Diagnosis & Tests | Prevention & Expectations | Treatment & Monitoring

An allergic reaction is an immune system response to exposure to a specific substance.

What is going on in the body?

Allergic reactions are fairly common. Most reactions happen soon after contact with an allergen. An allergen is a trigger that causes the reaction after touching a certain part of the body.

  • The blood may be exposed from an injection.
  • The blood or gut may be exposed from swallowing an allergen.
  • The lungs may be exposed from inhaling the allergen.
  • The skin may be directly exposed to an allergen.
  • Usually these reactions are mild and can be treated at home with simple methods. However, some people have a sudden, life-threatening allergic reaction within minutes, called anaphylaxis. Anaphylaxis can progress rapidly and result in shock and even death if medical help is not obtained quickly.

    Usually, the first exposure produces only a very mild reaction or no reaction at all. For some people, repeated exposure may lead to more serious reactions. Even a small amount of a trigger can lead to a serious reaction in some people. Allergic reactions can affect small areas or the entire body. Most reactions occur within seconds or minutes of exposure. However, some reactions can occur days or weeks after exposure.

    What are the causes and risks of the condition?

    There are few things that do not cause an allergic reaction in some people. However, most people never have an allergic reaction. Those with a family history of allergies are more likely to develop them. People with asthma, hay fever, or a skin condition known as eczema are more likely to develop allergies.

    Following are some of the common triggers:

  • bee stings
  • foods such as peanuts and shrimp, which can trigger a food allergy
  • medicines
  • metals
  • mold
  • pets with feathers or fur
  • pollens or plants
  • synthetic materials
  • tiny organisms such as bacteria


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    Allergic Reactions: Symptoms & Signs

    Author: James Broomfield, MD
    Reviewer: William M. Boggs, MD
    Date Reviewed: 08/21/01

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