what is patch testing for allergies
In a Patch Test, allergens are applied to patches, which are then secured on your skin with hypoallergenic tape. During the test, your skin may be exposed to 20 to 30 extracts of substances that can cause contact dermatitis or other chronic allergic inflammatory conditions. The procedure usually follows like this: 1  On day one of testing, tiny amounts of 50 or more substances are applied as small patches to your skin. This is usually on your back. They are fixed on with non-allergic tape.  After two days you return to the doctorâs office and the patches are removed.