Allergy Tests

Why It Is Done

Allergy testing is done to find out what substances (allergens) cause an allergic reaction.

Skin test

The skin prick test can also be done to:

• Identify inhaled (airborne) allergens, such as tree, shrub, and weed pollens, moulds, dust, feathers, and pet dander.
• Identify likely food allergens (such as eggs, milk, peanuts, nuts, fish, soy, wheat, or shellfish).
• Determine whether a person may be allergic to a medicine or insect venom.

Blood test

A blood test on a blood sample may be done instead of a skin prick test if a person:

• Has hives or another skin condition, such as eczema, that makes it hard to see the results of skin testing.
• Cannot stop taking a medicine, such as an antihistamine or tricyclic antidepressant, that may prevent or reduce a reaction to a substance even when a person is allergic to the substance.
• Has had a severe allergic reaction (anaphylaxis).
• Has had positive skin tests to many foods. Enzyme-linked immunosorbent assay (ELISA) can find out the foods that a person is most allergic to.

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Author:	Debby Golonka, MPH Ralph Poore	Last Updated: September 27, 2007
Medical Review:	Caroline S. Rhoads, MD - Internal Medicine Harold S. Nelson, MD - Allergy and Immunology Donald Sproule, MD, CM, CCFP, FCFP - Family Medicine
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