Medical Definition of Test, allergy scratch
Test, allergy scratch: Test done on the skin to identify the allergy substance (the allergen) that is the trigger for an allergic reaction.
A small amount of the suspected allergy-provoking substance is placed on the skin. The skin is then gently scratched through the small drop with a special sterile needle.
If the skin reddens and, more importantly, if it swells, then the test is read as positive and allergy to that substance is considered probable.
Last Editorial Review: 7/1/2016
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