Association of Hair Dye Use With Circulating Levels of Sex Hormones in Premenopausal Japanese Women

The study investigated the association between hair dye use and sex hormone levels in 431 premenopausal Japanese women. It found that women who used hair dyes for 10 or more years had about 14% higher plasma total testosterone levels compared to those who never used hair dyes. This association was particularly noted with permanent hair dyes. Additionally, a higher frequency of using non-permanent hair dyes was marginally linked to increased total and free estradiol levels. The study concluded that long-term hair dye use might be associated with increased testosterone levels, but emphasized the need for further research to replicate these findings.