Does Hair Dye Cause Cancer?

The evidence is mixed and depends on how you are exposed. The International Agency for Research on Cancer classifies occupational exposure as a hairdresser or barber as probably carcinogenic to humans, while personal use of hair colourants is not classifiable as to whether it causes cancer. The National Cancer Institute notes a 2010 meta-analysis of 42 studies that found hairdressers who had worked at least 10 years were nearly twice as likely to develop bladder cancer as people who had never been hairdressers.

For personal use, an NIH analysis of 46,709 women in the Sister Study found that women who regularly used permanent hair dye in the year before joining the study were 9 percent more likely to develop breast cancer than women who did not use hair dye. Among African American women, using permanent dye every five to eight weeks or more was associated with a 60 percent increased risk, compared with 8 percent for white women.

The same study found that women who used hair straighteners at least every five to eight weeks were about 30 percent more likely to develop breast cancer. An NIH co-author cautioned that, although there is some prior evidence for the association with chemical straighteners, the results need to be replicated in other studies.

Sources checked September 15, 2026. Every point below links the page it came from.

The sources behind this answer

  • Government sourceIARC classifies occupational exposure as a hairdresser or barber as probably carcinogenic to humans (Group 2A), and personal use of hair colourants as not classifiable (Group 3). IARC, World Health Organization ↗
  • Government sourceThe National Cancer Institute says a 2010 IARC report concluded that some of the chemicals professional hairdressers are exposed to are probably carcinogenic to humans. National Cancer Institute ↗
  • StudyThe National Cancer Institute says a 2010 meta-analysis of 42 studies found hairdressers who had worked at least 10 years were nearly twice as likely to develop bladder cancer as people who had never worked as hairdressers. National Cancer Institute ↗
  • StudyAn NIH analysis of 46,709 women in the Sister Study found regular use of permanent hair dye in the prior year was linked to a 9 percent higher breast cancer risk, and 60 percent among African American women using it every five to eight weeks or more. NIEHS, National Institutes of Health ↗
  • StudyThe same analysis found women who used hair straighteners at least every five to eight weeks were about 30 percent more likely to develop breast cancer. NIEHS, National Institutes of Health ↗
  • StudyNIEHS epidemiologist Dale Sandler cautioned that although there is some prior evidence for the association with chemical straighteners, the results need to be replicated in other studies. NIEHS, National Institutes of Health ↗

Sources checked September 15, 2026. A brand statement is the company’s own claim, which we report but have not verified. Our grades are model-based estimates, not lab tests.

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