Allergy Skin Test

If someone is thought to be allergic to any substance then it is usually diagnosed in the form of a skin test. This test is done in order to determine the allergen – or the substance that is triggering the allergic reaction.

Allergy Skin Test Process

The process for the allergy skin test firstly includes using a small amount of the substance that is suspected as being the allergen. It is placed into the skin, where the area of skin by this small drop is then scratched using a sterile needle, which is why the allergy skin test is also sometimes known as a scratch test.

A Positive Allergy Skin Test

An example of an allergy test could be a food allergy. The food that was suspected to trigger an allergic reaction would be dropped within a liquid onto the skin on the arm or back. Underneath this drop, a sterile needle will create a scratch. This area of skin will show allergic symptoms if the substance is the allergen – for example it may redden and swell. If so, then the allergy test is read as a positive test. This means that it is probably the patient is allergic to the food substance in question. If there are no such symptoms then the test will be read as negative.

If the test shows positive then this will suggest that the patient has an antibody (IgE antibody) that is what causes the skin to release histamine – bringing out redness and itching. This antibody reacts specifically to the allergen in question.

Useful Facts About Allergy Skin Tests

Skin tests are fast and simple, though severely allergic patients may experience a reaction known as anaphylaxis. If a patient is likely to experience such a reaction then skin tests are avoided, as they are in cases where patients have extensive eczema.