The Phi Patch Test is a method to determine if a substance that comes into contact with the skin (a product used during treatment) causes any kind of inflammation or allergic reaction. Performing an epicutaneous test for skin allergies Any cosmetic product can cause skin reactions in certain people. Possible reactions include redness and itching at the application site. Cosmetic products can also inflame existing skin conditions or, less commonly, cause more serious reactions such as infections, scars, allergies or changes in skin pigment. The Cosmetic Sensitivity Epicutaneous Test is an ideal hypoallergenic product used to perform an allergy test for a variety of cosmetic products. The epicutaneous test allows you to determine in advance whether a cosmetic product may cause irritation, so that you can avoid using such a product. The epicutaneous test is not recommended for clients taking cortisone/prednisolone or immunosuppressive medications as the results of the epicutaneous test may be invalid.