Allergy testing

Alternative names:

patch tests (allergy); RAST test; scratch tests (allergy); skin tests - allergy

What the risks are:

Skin tests and food allergy tests carry a risk that you will experience an allergic reaction when exposed to the allergens. Some sensitive persons will (rarely) experience a life-threatening anaphylactic reaction.

Penicillin (and closely related medications) are the only drugs that can be tested using skin tests. (Skin tests for other drugs are at best non-informative and can be dangerous).

Tests that are not proven as valid include cytotoxic testing (in which foods are mixed in a test tube with a sample of the person's blood and then the white blood cells are observed for a change in shape) and "provocation and neutralization" testing (in which the person is injected with a food or other substance and, if there is an allergic reaction, they are injected with more of the substance to "neutralize" the response; this can be very dangerous!).

Special considerations:

The accuracy of allergy testing is quite variable. Even the same test performed at different times on a person can give different results. A person can react to a substance during testing but never react during normal exposure. A person can also have a negative allergy test and yet still be allergic to the substance.