Hi,
Everyone do the hair color have this issue. Nowadays hair coloring products generally do not damage the hair, regardless of how often they are used.
In past hair coloring contains plenty of chemicals and various dye colors and pigments. These chemicals can harm hair over time, so proper care must be taken to ensure minimal irreversible damage. So some manufacturers add chamomile, amino acids, and sugar crystals to their colors to improve the condition of the hair, therefore reducing the effects of long-term coloring.
Modern hair colors have no reported carcinogens - cancer promoting agents.
