Aging gray hair: hair often starts to turn gray from both sides of the temples, initially a few gray hairs, then gradually increases and slowly progresses to the top of the head. Physiological senile gray hair that appears with age can be dyed if you particularly mind, but the hair dye may cause allergies and it is recommended to choose a better quality hair dye. Also, hair dyeing is not recommended for those with sensitive constitutions. Early gray hair: gray hair before reaching old age is called early gray hair. Pernicious anemia, hyperthyroidism, cardiovascular disease, severe headaches and high mental stress can cause gray hair. Some relevant tests can be done to find the cause of gray hair, exclude related diseases, and treat the symptoms under the guidance of a doctor. If it is a lack of trace elements in the body, you can eat some food that is good for hair growth and replenish the hair root nutrition; if it is a lack of sleep, tension and other reasons, you should relax, strengthen exercise and relieve the stress of life. Congenital gray hair: most of the congenital gray hair is limited whitening, manifested as a piece or several pieces of gray hair, often at birth, or occurs later in life, caused by a group of adjacent hair follicles melanin reduction or lack. There is usually no good treatment for this condition. White hair due to other factors: hair can turn white on the white patches of keloid, fine hairs at the beginning of baldness are white, gray-white hair can be present on the lesions of tuberous sclerosis, neurofibroma and scalp herpes zoster, and local hair can turn white after x-ray and radionuclide exposure. After treatment of the primary disease and healing of these diseases, the white hair may gradually return to normal color.