Do Hair Dyes and Straighteners Increase Breast Cancer Risk?
Hair products like dyes, relaxers, or straighteners contain many chemicals, some of which may have the potential to increase breast cancer risk in people who use them frequently. Researchers have been looking at this connection for decades. So far, they haven’t reached a definite conclusion.
People are exposed to the chemicals in hair products through the skin, through the hair follicles, and by inhaling fumes.
What chemicals are in hair products?
Most of the chemicals in hair products that are concerning fall into two broad categories:
Carcinogens are chemicals that are known or thought to be carcinogenic (capable of causing cancer). Some examples are formaldehyde, lead acetate, and para-phenylenediamine (PPD).
Hormone (or endocrine) disruptors can affect how estrogen and other hormones act in the body by blocking them or mimicking how they behave. This can throw off the body’s natural hormonal balance. Phthalates, parabens, bisphenol A (BPA), and formaldehyde are some of the hormone-disrupting chemicals that have been used in hair products.
A few of these chemicals have been banned from use in hair products sold in the E.U. and in other countries because of safety concerns, but most are not banned in the U.S. The FDA banned the use of lead acetate in hair dyes in the U.S. in January 2023 and has proposed a ban on formaldehyde in hair straightening products. And a new law, the Modernization of Cosmetics Regulation Act of 2022 (MoCRA), has given the FDA more authority to regulate the safety and labeling of hair products than it had in the past.
Still, compared to many other countries, the U.S. has relatively loose regulatory oversight of the safety of the ingredients in these products.
In addition, it can be hard to know what’s in a hair product just by reading the label because individual ingredients can go by different names. Also, companies are not required to list all of the ingredients they put in their products on the labels.
What the research shows about hair products and cancer risk
Overall, the results of studies that have looked at possible links between hair dyes and straighteners and the risk of breast cancer have been mixed and inconsistent. None of the studies conclusively show whether or not hair dyes and straighteners can cause breast cancer. But some studies have suggested that there could be a link between exposure to certain hair products and the development of breast cancer.
A study of U.S. women belonging to various ethnic groups published in the International Journal of Cancer in 2019 found an association between the use of hair dye and hair straighteners and breast cancer risk, especially for Black women. All the women in the study already had a higher-than-average risk of breast cancer, however, because they had at least one first-degree relative who had been diagnosed with breast cancer.
A study published in the journal Carcinogenesis in 2021 looked at hair product use in Black women. The researchers found that, overall, there seems to be no link between hair relaxers and breast cancer risk in Black women. However, there was some evidence that heavy use (at least seven times a year for 15 or more years) of hair relaxers containing lye may be linked to a higher risk of breast cancer
A study published in the journal BMJ in 2020 that included mostly white women found that longer-term use of permanent hair dye was associated with a greater risk of breast cancer.
A study published in the International Journal of Cancer in 2020 suggested that frequent use of straighteners and perming products during adolescence may be linked to a higher risk of premenopausal breast cancer.
Some of the ingredients in the products used by the women in these studies may be different from those on the market now. More research is needed to figure out which chemicals or formulations in the hair products that are on the market now might be associated with breast cancer risk. It’s a difficult topic to study because there are so many different product formulations and they keep changing over time.
People who start using permanent hair dyes and hair straighteners at a younger age and those who use them more frequently and for longer periods of time may be at higher risk.
It’s also important to know that these products may have other risks. For example, women who use chemical hair straightening products may be at a higher risk for uterine cancer and ovarian cancer. Thousands of people who developed uterine or ovarian cancer after using chemical hair relaxers have filed lawsuits against companies that manufacture these products, including L’Oreal, ShoftSheen-Carson, and others. These have been combined into one big lawsuit.
Steps you can take to reduce your risk
Consider using hair dyes and relaxers less often to reduce your exposure to the chemicals in these products.
Try semi-permanent, temporary, or plant-based dyes instead of permanent dyes. Research suggests that permanent dyes are more likely to increase breast cancer risk than other types of dyes.
Take safety precautions when you use dyes or relaxers, such as wearing gloves when applying the products, not leaving the products on longer than the directions say you should, and rinsing your scalp well with water afterward. Read more safety tips from the FDA.
Consider hairstyles (or options like wigs, weaves, or extensions) that don't require the use of hair dyes or straighteners.
Keep in mind that teens and tweens in particular should consider avoiding permanent dyes, straighteners, and perms.
— Last updated on April 29, 2025 at 9:24 PM