The method of turning white hair into black hair should be based on the causes of white hair formation. For biological reasons, such as age, old people's hair is gray. With the growth of age, white hair gradually increases, which is the performance of hair aging. The most direct and simple method is to dye hair. On the other hand, it is pathological, and white hair does not appear at a young age. Common causes, such as kidney disease and chronic kidney disease, patients will have gray hair earlier and will be obvious, and it can also appear during tumor treatment. There are also factors such as general nutritional status and sex hormones. According to the causes of white hair formation, targeted treatment or improvement can or may turn white hair into black hair.