The following came from Dr. Bradley Wolf located in Cincinnati, Ohio in response to one of his patient’s questions on hair dyes, mechanisms of actions and safety issues. Thanks Brad.
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Coloring hair to cover gray is a common practice. As hair continues to grow, color touch-up processes are performed so the new growth of gray hair matches the rest of the dyed hair. This touch-up process is normally performed on a 3-6 week basis.
With respect to the chemistry and hair damage – any type of processing of the hair leaves the fibers in a compromised state. The main culprits of colorants are high pH and hydrogen peroxide. These two components are responsible for the breakdown of keratin proteins inside the fiber. Extensive processing can lead to porous hair that feels rough, brittle, and unhealthy. The hair also takes on properties of being more hydrophilic.
Colorants are pretty mild these days and achieving damaged hair from usage is not prevalent. But you indicated that treatments were performed on a weekly basis. There is potential that excessive damage is occurring or may occur very soon if the practice continues which can lead to hair breakage.
Recommendations:
Undergo color treatments on a less frequent basis – every 3-6 weeks. Apply colorant product only to areas of hair that need color – roots. For more frequent treatments – use a semi-permanent level 1 or level 2 dyes which are much less damaging.
