Efficacy: This product is a natural plant formula, does not contain chemical hair dye, so do not need to do allergy testing. Compared with chemical hair dye, the operation is relatively trouble, the color is slow, and is not easy to penetrate, so the effect of black hair is slightly worse than that of traditional chemical hair dye, but it is very safe and healthy. Even if frequently used, no toxic side effect, and carcinogenic risk to any potential distortion.