Gray hair is mainly caused by genetic factors, physiological factors, lack of nutrition or mental stress, and needs to be dealt with according to the cause. Turning gray hair into black hair can be dealt with by coloring the hair, correcting nutritional deficiencies or relieving stress. 1. Genetic factors such as albinism can cause melanin formation disorders, resulting in white skin and hair; there are no specific drugs to treat it, but if it affects the aesthetics, it can be dealt with by coloring the hair. 2. Ageing will lead to the physiological degeneration of melanin cells, and then the symptoms of hair whitening; generally no treatment is needed, and the hair color can be changed through hair dyeing. 3. Preferential eating or picky eating caused by zinc, iron or vitamin B deficiency will also lead to the formation of melanin obstacles to the emergence of gray hair; the need for a reasonable diet, and under the guidance of the doctor in the amount of vitamins and other trace elements to supplement. 4. Mental stress, insomnia, anxiety, depression and other symptoms can also appear gray hair; must be psychological counseling, relieve mental stress to prevent the generation of gray hair. The sudden increase of gray hairs suggests timely medical treatment, after a clear diagnosis under the guidance of the doctor to avoid delays in the condition.