Does Hair Dye Increase the Risk of Breast Cancer?

What you need to know about dying your hair and breast cancer risk

A 2019 study by the National Institutes of Health suggests that the chemicals in permanent hair dye and chemical straighteners could increase a woman’s breast cancer risk.

The study found that permanent hair dye use was linked to a 45% higher breast cancer risk in Black women and a 7% higher risk in White women. The use of chemical straighteners was linked to an 18% increase in breast cancer risk.

Before you ditch the dye, however, it’s worth noting that breast cancer is caused by a number of factors and no one thing will guarantee a diagnosis. This article will look at what the research shows about hair dye so that you can make choices that are comfortable for you.

Salon owner straightening client’s hair in salon

Thomas Barwick / Getty Images

Is Dying Your Hair Bad?

Early hair dye formulations contained chemicals, including aromatic amines that were found to cause cancer in animals. In the mid- to late-1970s, however, manufacturers changed the components in dye products to eliminate some of these chemicals.

Some hair dye and hair straightening treatments like relaxers contain chemicals called endocrine disruptors that can interfere with your hormones. This hormone disruption is a concern, especially when it comes to hormone-driven cancers like breast, prostate, and ovarian cancers.

Only a minuscule amount of chemicals from hair dye are absorbed through the scalp, and it is not known whether some of the chemicals used in modern hair dyes contain cancer-causing substances.

Types of Hair Dyes 

Hair dye comes in different forms: permanent, semi-permanent, and temporary.

  • Permanent hair color: These dyes cause lasting chemical changes in the hair shaft. They are the most popular types of hair dyes because the color changes last until the hair is replaced by new growth.
  • Semi-permanent color: These dyes do penetrate into the hair shaft. They typically last for five to 10 hair washes.
  • Temporary hair color: These dyes cover the surface of the hair but don’t penetrate into the hair shaft. They generally last for one to two washes.

What Researchers Know About Hair Dye and Cancer 

Researchers have been studying the possible link between hair dye and cancer for a long time, but results have been inconsistent.

In a 2019 study, researchers at the National Institutes of Health looked at chemical hair dyes and straighteners to see if they were linked to increased breast cancer risk.

The study tracked 46,709 American women for an average of 8.3 years. All participants had a sister diagnosed with breast cancer but didn’t have breast cancer themselves when they enrolled in the research. After eight years of follow-up, the results showed:

  • Overall, women who regularly used permanent hair dye in the 12 months before joining the study were 9% more likely to develop breast cancer than women who didn’t use hair dye.
  • Black women who used permanent hair dye every five to eight weeks or more in the 12 months before joining the study were 60% more likely to develop breast cancer than women who didn’t use hair dye.
  • White women who used permanent hair dye every five to eight weeks or more in the 12 months before joining the study were 8% more likely to develop breast cancer than women who didn’t use hair dye.
  • Women who used chemical hair straighteners every five to eight weeks in the 12 months before joining the study were about 30% more likely to develop breast cancer than women who didn’t use chemical hair straighteners.
  • There was little increase in breast cancer risk among women who used semi-permanent or temporary hair dye.

It’s important to note that this study found an association between permanent hair dye and chemical hair straighteners and breast cancer; it is not a direct cause-and-effect relationship. That means using permanent hair dye and chemical straighteners may increase a woman’s risk of breast cancer, but using these products does not directly cause breast cancer.

What Isn’t Known

Researchers didn’t have the information on the chemical components of the products used by the women in the study and don’t give any suggestion as to why these hair products might increase breast cancer risk.

These findings disagree with results from some previous studies in this field. For example, a 2020 study of 117,200 women enrolled in the Nurses’ Health Study showed no positive correlation between the personal use of hair dye and risk of most cancers. Breast cancer risk was only increased in women with a specific subtype of breast cancer who reported using permanent hair dye 200 times or more in their lifetime.

This indicates more research is needed to fully understand the relationship between hair products and breast cancer risk.

Effect on Black Women

The results of the 2019 study showed that hair dye and straightening products impacted Black and White women differently.

According to the researchers, products marketed to Black women have higher concentrations of estrogens and endocrine-disrupting compounds. The color of dye and the frequency of use may be a factor.

  • Darker dye shades were associated with a 51% increased breast cancer risk for Black women, while lighter shades increased the risk by 12% for White women.
  • Frequent use of chemical straighteners was also associated with a 31% increased risk of breast cancer overall.

It’s important to note that the women in the study already had a higher-than-average risk of breast cancer because they had at least one first-degree relative who had been diagnosed with breast cancer.

What’s more, other research has contradicted this correlation between ethnicity, hair dye, and breast cancer risk, with one recent meta-review of 14 studies finding no association between hair dyes and breast cancer due to race, length of use, or dye color.

This suggests that the relative increased risk for Black women may be due to other variables such as income and access to health care that were unadjusted for in the original study. More research is needed to confirm the results.

Safety for Salon Professionals

The Department of Labor’s Occupational Safety and Health Administration (OSHA) has found that many hair smoothing products contain formaldehyde, formaldehyde dissolved in water (called methylene glycol), or other chemicals that can release formaldehyde during use. Using products that contain these substances can result in worker exposure to unsafe levels of formaldehyde.

Formaldehyde is a colorless, strong-smelling gas that presents a health hazard if workers are exposed. In 2004, the International Agency for Research on Cancer concluded that formaldehyde was a known human carcinogen.

OSHA says that the best way to control exposure to formaldehyde is to use products that do not list formaldehyde, formalin, methylene glycol, or any of the other names for formaldehyde on the label.

Safety With at-Home Dyes

For people who want to dye their hair but are concerned about safety, the Food and Drug Administration offers some suggestions:

  • Follow all directions on the label and in the package.
  • Keep hair dyes away from your eyes, and do not dye your eyebrows or eyelashes. This can hurt your eyes and may even cause blindness.
  • Wear gloves when applying hair dye.
  • Do not leave the product on longer than the directions say you should. Keep track of time using a clock or a timer.
  • Rinse well with water after using hair dye.
  • Keep hair dyes out of the reach of children.
  • Do not scratch or brush your scalp for three days before using hair dyes.
  • Do not dye your hair if your scalp is irritated, sunburned, or damaged.
  • Wait at least 14 days after bleaching, relaxing, or perming your hair before using dye.

Non-Toxic Hair Dye 

Some newer hair dye products are vegetable-based. These products may have some drawbacks, such as not being able to change hair color drastically or having the color fade sooner than is seen with permanent dyes, but they may be another option for people concerned about hair dye safety.


While the results from the 2019 study show that hair dye and chemical straightening may increase the risk of breast cancer, the issue is complex because not all hair dyes are the same—they can contain any of thousands of different chemicals. More research is now needed to understand how different compounds found in common hair products could potentially be involved in the development of breast cancer.

A Word From Verywell

While the research on the dangers of hair dye has been mixed, scientists agree that maintaining a healthy weight, keeping physically active, and drinking less alcohol can help lower your cancer risk. Smoking is a known risk factor for cancer, and quitting smoking can improve your health, regardless of whether or not you use hair dyes.

Limited research does suggest permanent hair dye and chemical straighteners may increase a woman’s risk of breast cancer, but using these products does not directly cause breast cancer.

Frequently Asked Questions

  • Does hair dye cause cancer?

    Some research suggests using permanent hair dye and chemical straighteners may increase a woman’s risk of breast cancer, but using these products does not directly cause breast cancer.

  • Is it safe for recovering cancer patients to dye their hair?

    It’s generally recommended that you avoid using hair dyes for at least six months after finishing your cancer treatment, to avoid placing your hair under any additional stress and to give your hair follicles and scalp a chance to recover.

  • Which hair dyes increase the risk of formaldehyde exposure?

    It is unclear which hair dyes may increase formaldehyde exposure, but professional keratin hair smoothing treatments can contain formaldehyde or formaldehyde-releasing chemicals. Using these can raise indoor air concentrations of formaldehyde to levels that could be a potential hazard.

  • How can Black women practice safe hair care?

    Cutting back on hair dye and straightening is potentially one of many things that you could do to reduce your risk for breast cancer. There was no increased risk for women who used semi-permanent or temporary dyes, the kind that eventually washes out with shampooing.

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8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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