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    What Is an Allergic Reaction?

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    Some people sneeze like crazy. Others get itchy hives or watery eyes. But whatever the reaction, it boils down to one thing: allergies.

    If you have allergies, you have lots of company. As many as 30% of U.S. adults and 40% of children are in the same boat as you.

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    While your problem may seem to start in the nose or the eyes, allergies actually come from an immune system run wild.

    Learning why these reactions happen can help you keep things under control and feeling better.

    Why Allergic Reactions Happen

    Your immune system has an important job: to defend your body from invaders such as bacteria and viruses that mean you harm.

    But when it makes war on substances it shouldn’t, that’s an allergy.

    Peanuts, eggs, or pollen, for example, can trigger reactions. They are called allergens.

    During a reaction, your immune system releases antibodies. These are proteins that deliver a message to cells: Stop that substance! The cells then send out histamine, which causes blood vessels to expand, and other chemicals, and these trigger the allergy symptoms.

    These antibodies are singled-minded. Each one targets only one type of allergen. That explains why someone might be allergic to peanuts but not to eggs.

    You can come into contact with allergens in many ways: through the skin, eyes, nose, mouth, or stomach. This can cause your sinuses to clog up, inflame your skin, make it harder to breathe, or cause stomach problems.

    What Things Most Often Cause an Attack?

    Why do some people have such bad allergies and others don’t? Experts don’t have all the answers, but they say family history is important.

    Some common allergens include:

    ●    Animal dander

    ●    Bee stings

    ●    Certain medications such as penicillin

    ●    Dust mites

    ●    Foods -- particularly peanuts, tree nuts, fish, shellfish, eggs, milk, wheat, and soy

    ●    Insect bites

    ●    Latex or other materials you touch

    ●    Mold

    ●    Plants and pollens

    The Symptoms, From Itchy Eyes to Sneezing

    Your allergy attacks might range from mild and annoying to more severe and even life-threatening. It all depends on the way your body reacts and how much of the allergen got into your system.

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