Allergies are a common and chronic condition that involves the body's immune system. Normally, your immune system works to fight off viruses, bacteria, and other infectious agents. When you have an allergy, your immune system treats a harmless substance, like dust or pollen, as a threat. To fight this perceived threat, your immune system makes antibodies called immunoglobulin E (IgE).

Substances that cause an allergic reaction are called allergens. Besides dust and pollen, other common allergens include animal dander, foods, including nuts and shellfish, and certain medicines, such as penicillin. Allergy symptoms can range from sneezing and a stuffy nose to a life-threatening complication called anaphylactic shock. Allergy blood tests measure the amount of IgE antibodies in the blood. A small amount of IgE antibodies is normal. A larger amount of IgE may mean you have an allergy.

Other names: IgE allergy test, Quantitative IgE, Immunoglobulin E, Total IgE, Specific IgE

Your health care provider may order allergy testing if you have symptoms of an allergy. These include:

• Stuffy or runny nose
• Sneezing
• Itchy, watery eyes
• Hives (a rash with raised red patches)
• Diarrhea
• Vomiting
• Shortness of breath
• Coughing
• Wheezing

If your total IgE levels are higher than normal, it likely means you have some kind of allergy. But it does not reveal what you are allergic to. A specific IgE test will help identify your particular allergy. If your results indicate an allergy, your health care provider may refer you to an allergy specialist or recommend a treatment plan.

Your treatment plan will depend on the type and severity of your allergy. People at risk for anaphylactic shock, a severe allergic reaction that can cause death, need to take extra care to avoid the allergy-causing substance. They may need to carry an emergency epinephrine treatment with them at all times.

Be sure to talk to your health care provider if you have questions about your test results and/or your allergy treatment plan.

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