What is the sensitivity test and how do I perform it correctly before coloring?

Every permanent hair dye carries a risk of allergic reaction, even if you have used similar products before. The sensitivity test (patch test) is a mandatory safety step. Prepare a tiny quantity of the mixture exactly as you would for full application — combine a pea-sized amount of color cream with the corresponding amount of developer in a non-metallic bowl. Using a cotton bud, apply a thin layer to a discreet area of clean, dry skin, typically behind the ear or on the inner forearm. Leave it uncovered for 48 hours without washing the spot. During this period, watch for any redness, itching, burning, swelling, or blistering. If any reaction occurs, rinse immediately and do not use the product. Even if no reaction appears, wait the full 48 hours before proceeding to full-head application. This test does not guarantee zero risk, but it significantly reduces the chance of a severe scalp reaction during coloring.