A patch test and strand test is essential before beginning a hair color or lightening process. MANIC PANIC® Hair Color is PPD FREE but some people do develop allergies to different color dyes throughout their lives. For that reason you should always perform a patch test! Select a small test area, about the size of a quarter, behind the ear or in the inner fold of the elbow. Wash the test area gently with mild soap and water. Dab dry with a clean towel. Cover the clean test area with a thin coat of the specific shade of Manic Panic Hair Color desired. Allow the test area to dry. Leave it uncovered and undisturbed for 24 hours. Examine the test area carefully. If there are any signs of irritation, then under no circumstances should the product be used. Should you have any further concerns, please consult a licensed dermatologist. If the patch test goes well, move on to the strand test!