Allergy refers to the hypersensitivity of the body's immune system to an allergen in contact with the skin. The most common allergens are preservatives, and fragrance. Dermatologists perform Allergy tests called Patch Testing to help identify the allergen.
Allergy patch testing involves, 60 different allergens applied onto areas of normal skin, usually on the upper back, with the help of a non-allergenic tape. The nurse will remove the patches after 2 days and a doctor will review you again after 4days and discuss the results. The area must remain dry until the final reading. Doubtful reactions may require additional tests.