HealthWise KnowledgeBase
Allergy Tests
Results
A skin or blood test can tell you what substance, or Reference allergen Opens New Window, may trigger an Reference allergic response Opens New Window.
Skin tests
Skin tests work by exposing a person to suspected allergens and seeing if a reaction occurs. The results of the skin tests will be available immediately after testing is done.
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Normal (negative): |
No raised red areas (called wheals) are created by the allergen. |
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Abnormal (positive): |
A wheal created by the allergen is at least 1/8 inch (3 mm) larger than the reaction to the negative control. The larger the wheal, the more certain it is that the person is allergic to that specific allergen. |
Blood tests
Allergy blood tests look for substances in the blood called antibodies. Results of allergy blood tests are usually available in about 7 days.
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Normal (negative): |
The levels of immunoglobulin E (IgE), a type of Reference antibody Opens New Window, are the same as in a person who does not have allergies. |
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Abnormal (positive): |
The levels of immunoglobulin E (IgE) antibodies for a particular allergen or group of allergens are 4 times the normal level. |
| By: | Reference Healthwise Staff | Last Revised: Reference June 30, 2011 |
| Medical Review: | Reference E. Gregory Thompson, MD - Internal Medicine
Reference Rohit K Katial, MD - Allergy and Immunology |
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