The only sure fire way to determine a food allergy is a history of reaction to the food. However there are times when a person might not know the exact food that is the causing the reaction. This is when allergy testing comes into play.
There are two types of allergy tests; skin prick and blood. This article will discuss skin prick testing, also known as scratch testing.
Skin prick, or scratch testing, involves scratching the surface of the skin and applying the protein of the allergen or allergens in question. If there is little to no skin reaction, the result is deemed negative. If there is a skin reaction, it is assumed that the individual is allergic to that allergen.
Skin reaction results can vary but usually include a hive or welt on the skin. The allergist will measure this welt and make note of its size for future testing reference. In rare instances skin prick testing can cause further allergic reactions like full body hives and even anaphylaxis. This is uncommon. Skin prick testing is deemed safe for most individuals unless there is a history of anaphylaxis to the test.
The downside of skin prick testing for an allergy diagnosis is that there is a high false positive results rate. People with eczema or sensitive skin should be especially cautious as both can cause positive test results when there is no allergy.
Skin prick results should be considered along with history of reaction and possibly blood testing. If you are concerned about your allergy testing results, you should consult your allergist.