In what scenario is a patch test especially important?

A patch test is especially important when applying hair color because it helps determine whether an individual has an allergic reaction to any of the ingredients in the dye. Hair color products often contain strong chemicals, including ammonia and peroxide, which can cause skin irritation or allergic reactions in some people. By performing a patch test at least 48 hours prior to full application, a small amount of the product is placed on a discreet area of the skin, such as behind the ear or on the inside of the elbow, allowing you to observe any adverse reaction. This precautionary step is critical in ensuring the safety of the client and preventing potentially severe reactions during the coloring process.