Hair Relaxers and Uterine Cancer

Yes, research has linked uterine cancer to the frequent use of hair relaxers or straighteners. The Sister Study discussed in detail below found that women using chemical hair straighteners are at a higher risk of uterine cancer than women not using these products. The researchers uncovered no similar connection with other hair products, like dye, bleach, highlights and perms.

Two recent studies have linked hair relaxers to uterine cancer.

The Sister Study

The Sister Study, which began in 2003, was a comprehensive study conducted by the National Institute of Environmental Health Sciences (NIEHS). The study followed nearly 34,000 U.S. women ages 35 to 74, and did so for more than a decade. The researchers examined risk factors for breast cancer and other health conditions related to chemical hair-relaxer use. Among those who participated, 378 developed uterine cancer. 

Here are a few key takeaways:

• Women who used hair relaxers more than four times during the previous year were more than twice as likely to develop uterine cancer than women who didn’t use chemical hair straighteners. 
• The study concluded that approximately 1.64% of those who hadn’t used hair relaxers would develop uterine cancer by age 70. However, the uterine cancer risk for those who frequently used the products was estimated higher, at 4.05%. 
• Black women made up approximately 60% of the people participating in the study. The researchers found that Black women might deal with more adverse health effects due to their common and frequent use of hair relaxers, the presence of toxic chemicals in chemical straighteners, and the relatively young ages at which they might begin using the products.

Black Women’s Health Study

A Black Women’s Health Study that Boston University published in 2023 found a relationship between extended use of chemical hair straighteners and uterine cancer in women who’ve gone through menopause. 

The study of nearly 45,000 women followed those with no history of cancer for as long as 22 years, comparing rates of uterine cancer among those who used hair relaxers versus those who didn’t. The researchers concluded:

• Women who used hair straighteners more than twice a year or for more than five years had a 50% or higher risk of uterine cancer than women who never or rarely used chemical hair relaxers. 
• Black women experience aggressive forms of uterine cancer at higher rates and are almost twice as likely as non-Hispanic white women to die from the disease.

Terms to know

You need to be familiar with a few terms to better understand the connection between hair relaxers and uterine cancer. These terms include:

• Chemical hair relaxers: Products marketed mainly to Black and Brown women to control natural hair by making it smoother, straighter and more manageable
• Endometrial cancer: A form of cancer that starts as a growth of cells in the lining of the uterus 
• Uterine cancer: A form of cancer affecting the uterus (There are two types of uterine cancer: endometrial cancer and uterine sarcoma. The former impacts the lining of the uterus, while the latter attacks the uterine wall.)

Hair relaxers may increase a woman’s risk of uterine cancer. Relatively recent studies investigating risks of breast cancer related to hair-relaxer use found that women using the products were at a higher risk of developing uterine cancer than women who hadn’t used them. The studies showed black women to be at greater risk due to their widespread use of hair relaxers.

Harmful chemicals found in hair relaxers and straighteners

Research has found a link between dangerous health conditions and harmful chemicals contained in chemical hair relaxers and straighteners. Associated health conditions include uterine cancer in women who use these products. Among the harmful chemicals that hair relaxers and straighteners may contain are:

• Cyclosiloxanes: Research has connected cyclosiloxanes with neoplastic responses (the uncontrolled and excessive growth of cells) leading to uterine tumors in rats.
• Di(2-ethylhexyl)phthalate (DEHP): A toxic man-made chemical, DEHP has been classified by the International Agency for Research on Cancer (IARC) as potentially carcinogenic to humans. 
• Endocrine-disrupting chemicals (EDCs): These chemicals, or combinations of chemicals, disrupt the human endocrine system.
• Formaldehyde: A common ingredient in chemical hair straighteners, even in products labeled as formaldehyde-free, formaldehyde enters the air when the relaxer is heated during use. The U.S. Department of Health and Human Services’ National Toxicology Program (NTP) and the World Health Organization’s International Agency for Research on Cancer (IARC) have both classified formaldehyde as a known human carcinogen.
• Parabens: EDCs used in chemical straighteners, parabens may affect estrogen levels. Research has linked parabens to uterine fibroid tumors, premature puberty and endocrine disruption. 
• Phthalates: These are chemicals used to make fragrances in cosmetics more stable and help topical products adhere to and pass through skin and hair. Phthalates are known EDCs that pose a risk to human health. 

What other types of cancer are linked to hair relaxers?

Apart from uterine cancer, hair relaxers have been linked to ovarian cancer and breast cancer. Sister Study researchers found that ovarian cancer risk doubled in women who used hair relaxers more than four times in the previous year, compared to those who didn’t. 

What hair relaxers cause uterine cancer?

Certain hair relaxers may cause uterine cancer. These hair relaxers include products made by Godrej Consumer Products Ltd, L’ORÉAL USA, Namaste Laboratories, LLC and others. Because these companies didn’t warn consumers about the potential harm in their products, users experienced dangerous side effects — including cancer.

Yes, people began to file hair relaxer lawsuits after a 2022 study connected chemical hair relaxers to an increased risk of uterine cancer. As of August 1, 2024, more than 9,150 such claims are consolidated into multidistrict litigation in MDL 3060. These lawsuits assert that the chemicals contained in hair relaxer products cause serious health conditions, including cancer.

The hair relaxer cases allege that the defendants:

• Knew or should have known of the risks associated with hair-relaxing chemicals
• Marketed dangerous chemical straighteners without warning consumers
• Misrepresented hair relaxer products as “safe” and “natural”
• Reinforced traditional standards of beauty and negative stereotypes about afro-textured hair

Research indicates that Black women who frequently use hair relaxers containing harsh chemicals are at greater risk for adverse health effects like uterine cancer. Also noteworthy: Black women with uterine cancer generally have worse prognoses than white women. 

Approximately 3% of all new cancer diagnoses involve uterine cancer. In 2022, nearly 66,000 new cases of uterine cancer popped up in the U.S. The median age of women diagnosed with uterine cancer is 63 years old. 

Uterine cancer symptoms

Uterine cancer symptoms commonly include:

• Pain in the lower abdomen
• Pelvic cramping directly below the stomach
• Prolonged, heavy or frequent vaginal bleeding in women over 40
• Slight or moderate vaginal bleeding or spotting after menopause
• Thin, clear or white vaginal discharge in postmenopausal women
• Vaginal bleeding between periods in premenopausal women

What chemicals are linked to uterine cancer? 

Endocrine-disrupting chemicals (EDCs), which interfere with hormone production, are linked to uterine cancer. Even slight variations in hormone levels can lead to severe health effects.  Some adverse effects related to changes in a woman’s hormones include reproductive problems, infertility, cancer, cognitive issues, immune disorders and metabolic syndrome.

EDCs negatively affect hormone production by:

• Acting on hormone receptors to control hormone delivery
• Blocking hormone stimulus 
• Causing the body to over-respond to stimuli
• Increasing or decreasing hormone levels 
• Mimicking the effect of estrogen, increasing disease risk

EDCs are associated with various negative health outcomes, including various types of cancer.

No, the FDA has not banned hair-relaxing products. In 2023, the U.S. Food and Drug Administration (FDA) proposed a ban on formaldehyde and formaldehyde releasing chemicals in hair relaxers due to its connection to cancer and other serious, long term health effects. However, to date the FDA has not yet implemented the proposed rule.

Many people have been impacted by ovarian cancer, uterine cancer or endometrial cancer allegedly caused by using chemical hair relaxers. If you believe you’ve been similarly impacted by toxic exposure to hair-relaxer chemicals, consider discussing your options with an attorney who has experience in multidistrict litigation (MDL).

Our attorneys have a depth of experience supporting people facing life-altering health problems. We have knowledge that can help you weigh your legal options.

Motley Rice leads litigation brought by thousands of women harmed by defective products. Our law firm has extensive experience litigating product liability lawsuits for women who:

• Developed ovarian cancer after using talc-based baby powder for feminine hygiene 
• Suffered breast implant-associated anaplastic large cell lymphoma (BIA-ALCL) allegedly caused by Allergan breast implants
• Endured severe complications allegedly caused by birth control devices such as Essure® and Paragard® and complications arising from the use of transvaginal mesh

We invite you to reach out to our attorneys at any time to discuss a potential case.