It is healthiest to dye your hair several times a year.

Hair dyeing can cause cancer, especially black hair. Organic solvents in dyes can cause leukemia. I suggest you dye it twice a year and use good dyes. According to the news report, a woman got leukemia after dyeing her hair continuously 15 years. Preventive measures L. People with a history of allergies should be careful when dyeing their hair; 2. Don't dye your hair after dyeing dermatitis; 3. Don't use hydrogen peroxide or other solvents to remove hair dye, which is ineffective and harmful; 4. Don't use hair dyes frequently for a long time, especially chemically synthesized hair dyes; 5. Choosing the high-quality products produced by regular manufacturers is not harmful to health. In addition, if you have hair dye dermatitis, remember to go to the hospital in time to prevent the disease from getting worse and spreading to the face, neck, eyelids and upper chest, which will bring further inconvenience to life. Good wishes! Think about health first!