There are currently 2 ways to test for peanut or other food allergies. Skin prick testing and blood testing.
Skin prick or scratch testing is when the skin is scratched a small amount of the allergen protein is placed on the scratch to determine whether there is an allergy or not. A hive or welt appearing typically means there may be an allergy to that food.
There are a few types of blood tests, one of the most common one known is RAST as well as Immunocap. In blood testing, a blood sample is drawn and can be tested for a variety of allergies–food or otherwise.
On a recent episode of The Doctors, a new test called component resolved diagnoses (CRD) was discussed. While not FDA approved in the United States, this test is being used in Europe.
Doctors are learning that some peanut proteins, specifically ARA H1, h4 and H3 cause more severe reactions in those allergic compared to other peanut proteins individuals might be allergic to. CRD testing is said to be able to determine specifically what peanut protein an individual is allergic to and therefore know whether the reaction might be severe or mild based on the protein.
More information can be found at the following links:
Ruth LovettSmith is the mother of a child with multiple life threatening food allergies and founder of Best Allergy Sites: Your Food Allergy and Gluten Free Guide http://www.bestallergysites.com/