Studies Link Hair Relaxers To Cancer. Many Doctors Question The Data (2024)

Jaye Hall was 9 years old when she first relaxed her hair. What started as a one-time trial for her elementary school graduation quickly shifted to routine. Every six weeks, to be exact. Straight hair heightened her ability to feel pretty. “Once I saw that my hair was straight, I was addicted,” she said.

But straight hair came at a cost, as the product would often burn her scalp. “I wanted my roots straight. If I took the relaxer off too soon I would end up with puffy roots,” she says.

At age 21, Hall was diagnosed with polycystic ovarian syndrome, causing her to question the relationship between relaxers and her health.

Scientists have long searched for either an association or causation between hair products and health outcomes, including infertility, alopecia, fibroids and early menarche. Two longitudinal cohort studies—the Black Women Health Study and the Sister Study—have received attention for raising the possibility that hair relaxers could be associated with uterine cancer. But many question the data behind their findings.

Black Women Health Study

The Black Women Health Study started in 1995 and tracks the health and illnesses of 59,000 Black women via biennial questionnaires. Respondents provide information about their medical history, such as their weight, medications and diet. Two years after the study launched, amid widespread use of relaxers, researchers added questions about hair products to the survey. Dr. Kimberly Bertrand, epidemiologist at Slone Epidemiology Center, and her team recently studied if relaxers could increase the risk of uterine cancer for Black women.

The authors recruited Black women who were cancer free as of 1997, when they first reported their hair relaxer use. These women were followed for 20 to 25 years to observe who developed cancer and who did not. The study population included only Black women, and 95% of the cohort reported using relaxers in the past. This created a statistical challenge of purely comparing those who have used relaxers to those who have never. Still, Bertrand’s results raised concerns about relaxers. “Postmenopausal uterine cancer women who used relaxers more than twice a year or for more than five years had more than a 50% increase in risk of uterine cancer,” she states.


NYT ‘Strands’ Hints, Spangram And Answers For Wednesday, July 10th
Northern Lights Alert: Beware ‘Head-On’ Aurora Displays Say Scientists
‘The Acolyte’ Episode 7 Recap And Review: Woo-Hoo, Witchy Woman

In my conversation with Bertrand, she astutely calls out the difference between relative risk and absolute risk. When interpreting the 50% increase in relative risk of uterine cancer for postmenopausal women who use relaxers, one needs to take into account that uterine cancer is not very common; it accounts for about 3.5% of all cancers. Therefore, the absolute risk is probably much lower, as “you are multiplying an uncommon cancer by 50%, so you’re still going to be in the uncommon range,” she adds.

Sister Study

The Sister Study started in 2003 and follows 50,000 women between ages 35-70 who have a sister with breast cancer. The study goal is to learn how genetics and environment affect the risks of developing cancer. Dr. Alexandra White, leader of the National Institute of Environmental Health Sciences’ Environment and Cancer Epidemiology group, and her team recently studied the relationship between hair products and uterine cancer.

Unlike the Black Women Health Study, 86% of participants in the Sister Study were white and 7% were Black. The Sister Study also differed by not asking questions specifically about relaxers. Survey participants reported on more general hair product use during the prior 12 months. Results showed that those who used straightening products — like keratin treatments, flat irons, or relaxers — more than four times in the previous 12 months were twice as likely to develop uterine cancer compared to those who never used them. The risk of uterine cancer by age 70 for those who never used straightening products was 1.64% versus 4.05% for those with frequent use.

“The association was strong among frequent users, which supports the plausibility of the link,” White adds. However, she believes more research is needed and that she cannot definitively state that straighteners, like relaxers, cause cancer.

Both studies have heightened a much-needed discussion about avoidable environmental causes of cancer. However, as with any questionnaire, there are clear limitations that might reduce its validity and impact.

Some physicians and researchers not involved with these studies are less convinced that current data imparts a strong association between relaxers and cancer.

Information Collection

Dr. Kemi Doll, gynecologic oncologist in the UW Medicine Department of Obstetrics and Gynecology, believes these studies paved the road to later find definitive answers. Her consideration with the Sister Study was that “it was a survey study so we are basing [conclusions] on women reporting what they have been exposed to.” Questionnaires are vulnerable to bias, especially if participants have to recall behaviors from the past. Surveys are able to help generate a hypothesis, but rarely are they able to definitively find a cause for an outcome like cancer.

While the published data in both studies focused heavily on trends with product use, neither did a dive deep into the population of women who straighten their hair. “The group of women who straighten their hair are inherently different from women who don’t,” theorizes Dr. Sharon Malone, board-certified OB/GYN and author of Grown Woman Talk.

Perhaps women who straighten hair avoid moisture, like sweat. Assessing frequency of exercise for those who straighten their hair and develop cancer could provide further information, as obesity is a known risk factor for uterine cancer. Or, perhaps Black women who have more stressful jobs feel the need to straighten their hair. “All of these other factors that go along with having to straighten hair could be separate from the straightener itself,” Malone explains.

Neither survey solicits particular product brands used nor specifics regarding the relaxer application process. “We don’t have actual information on what kind of straightener, to what extent they were on the scalp... the strength or chemical makeup,” Doll says. Chemical exposure and personal risk depends on the ingredients, application technique and ventilation of the home or salon. Part of this problem is out of the hands of researchers. Often the ingredients in relaxers are extensive, variable and concealed by manufacturers as proprietary formulations. Plus, long and detailed questionnaires are less likely to be completed.

Grouping Of Products

“The most common active ingredients [of relaxers] are sodium hydroxide, potassium hydroxide, lithium hydroxide or guanidine hydroxide,” says Dr. Charlotte Goldfine, medical toxicologist at Harvard Medical School. “These are the same ingredients that are used in detergents and drain and oven cleaners.”

Sodium hydroxide, and the other hydroxides found in relaxers, have not been shown to be carcinogenic. Relaxers are different from keratin treatments and Brazilian blowouts as the latter contain formaldehyde as their active ingredient. Formaldehyde is a known carcinogen and can be found in glues, paints and building insulation, for instance.

Categories of hair products are often grouped or incorrectly interchanged. A criticism with the 2022 Sister Study is that various types of straighteners — including products with formaldehyde as an active ingredient — were combined into one category. “Flat iron, relaxers and keratin treatments were all considered the same,” says Dr. Crystal Aguh, dermatologist and author of 90 Days to Beautiful Hair. However, these products are different in mechanism and active ingredients.

The researchers mention that they were unable to separate out the people who flat iron their hair, an arguably lower risk process. “The most common way to straighten your hair is through a flat iron. If you remove them from the large category of hair straighteners, you aren’t going to have enough people to test for statistical significance,” says Aguh.

Short Reporting Period

Participants of the Sister Study were asked to report their hair product usage for the past 12 months prior to the questionnaire. “If you want to make a case, then you look at trends of five years or 10 years,” Malone adds.

As I wrote this article I remembered my time in medical school. I relaxed my hair two to three times a year, but I haven’t done so for five years. Though I applaud any research aiming to solve health disparities, the research in either case cannot help me assess my own risk as I’m not post-menopausal and I haven’t used a relaxer for the past 12 months.

Hormone Inconsistencies

Uterine cancer is classified into two types: Type 1 is hormone-responsive and Type 2 is not hormone-responsive. Type 1 uterine cancer is thought to be triggered by hormone disruptors, such as parabens and phthalates. If parabens and phthalates are the reason uterine cancer rates are rising then we should see rates of Type 1 cancer increasing in nearly all women — as both hormone disruptors are ubiquitously found in soaps, conditioners, perfumes, and makeup. Interestingly, Malone says it is actually Type 2 uterine cancer that is increasing, and that Black women outpace white women in having non-hormone dependent uterine cancer: “The theory of uterine cancer and relaxers being related to hormones in products is all wrong.” If the rise in Type 2 uterine cancer is from relaxers, the culprit ingredient has yet to be identified. The active ingredient in relaxers are hydroxides, such as sodium hydroxide, which is not found to affect hormones or cause cancer.

Unfair Blame

In recent years, Black women have been using straightening products less and wearing natural hairstyles more. They’re also not the only women who use straightening products. In the Sister Study, 60% of study participants using straighteners, relaxers, or pressing products were Black women and 40% were white or Hispanic/Latina women.

Malone finds herself struggling to deal with the volume of blame against Black women. The literature, even beyond these two studies, “keeps pointing to Black women and labeling something we are doing wrong,” she says. Black women are currently using relaxers less than ever before, and yet, rates of uterine cancer are still increasing. She fears this focus on Black women is diluting the confirmed problems: the incidence of uterine cancer is going up. And Black women are more likely to die from it.

It is important for Black women to know that even if they stop relaxing their hair, the risk of uterine cancer will not disappear completely. The authors of both studies disclose they only found an association and not causation, however the message that gets to the general public is largely changed and sensationalized. Malone believes the media coverage that follows research studies often deflects the attention from what matters: “telling people to look out for post-menopausal bleeding or if you have a period of PCOS and you have two periods a year — those scenarios put you at risk for cancer.”

Understanding The Stakes

The conversation about hair care for Black women is a delicate one, as the impact of using relaxers extends beyond health. For many, hairstyles and hair care is an essential aspect of their identity — especially in the workplace. “In a setting that is predominately white, I can still feel like I am looked at differently based on my hairstyle,” Hall says. She now wears natural hairstyles but stated that straight hair would make the workplace easier to navigate.

Natural hairstyles have their own risks. “It is not enough [for doctors] to tell women to stop using relaxers and just walk out of the room,” says Aguh. She shares that the decision to wear natural hairstyles and spend significant time in braids, weaves, or wigs is causing permanent alopecia. “Alopecia clinics are filled to the brim of women with permeate hair loss in their early 30s because someone told them if they went natural everything would turn around.” Most importantly, wearing natural hairstyles is not decreasing rates of uterine cancer as these rates continue to climb.

Future Directions

After reviewing dozens of articles on the topic, I applaud all researchers for attempting to resolve important and complex healthcare issues. Bertrand is hopeful more studies will unfold. “To date we have two studies exploring the relationship between uterine cancer and relaxers. We don’t have the quantity of the evidence yet to make a strong claim.” She knows that despite many studies being consistent, there needs to be an actual chemical that is named the culprit. “No observational study can determine the exact cause,” she adds.

With more robust research there will hopefully be policy change. The FDA has yet to publicly announce its decision to ban the use of formaldehyde in hair straighteners, specifically keratin treatments. If the FDA ban is passed, relaxers will likely be unaffected because they don’t have formaldehyde.

Until then, here are considerations I gathered from a multidisciplinary team of doctors:

  • Instead of only asking your doctor, “Should I use relaxers?” ask about the signs and symptoms of breast and uterine cancer. Ask them to review your personal risk factors.
  • Understand that it’s unlikely a single product is causing the widespread increase of cancers in adults. “It's the cumulative burden of all of the unnamed chemicals, pesticides, herbicides, pharmaceuticals, preservatives, and petroleum derivatives that are inescapable in western civilization,” says Dr. Diana Molavi, chief of pathology at Sinai Hospital in Baltimore.
  • Consider decreasing your use of cosmetic products overall. “Most dermatologists would discourage use of too many hair products and treatments as we often see patients with complications, such as allergic contact dermatitis, irritant contact dermatitis and hair loss,” says Dr. Kelly Park, a board certified dermatologist and Mohs surgeon at the Illinois Dermatology Institute.
  • Decide if you would like to seek legal representation against manufacturers of these products as the research continues to expand. Colette McEldowney, lawyer at Rueb Stoller Daniel, says clients need formal medical records that demonstrate a diagnosis of cancer. Patients do not need documented paper trails of all prior over-the-counter or salon transactions. “Their word is enough and they will need to sign an affidavit of use to the product,” says McEldowney.
  • Accept the way Black women want to wear their hair. “Systemic biases may put pressure on Black women to choose things like relaxers or straighteners, which can lead to racial differences in health outcomes,” says Karen Tang, gynecologist and author of It’s Not Hysteria.
  • Understand the strength of a research study as well as its limitations. Surveys are a start to a conversation and help guide further research. The results, however, are rarely definitive and still require individuals to review their own risk tolerance.
Studies Link Hair Relaxers To Cancer. Many Doctors Question The Data (2024)


Studies Link Hair Relaxers To Cancer. Many Doctors Question The Data? ›

Results showed that those who used straightening products — like keratin treatments, flat irons, or relaxers — more than four times in the previous 12 months were twice as likely to develop uterine cancer compared to those who never used them.

What hair treatments are linked to cancer? ›

Permanent chemical hair straighteners and other hair products are most strongly associated with hormone-sensitive cancers, including health risks like uterine, breast and ovarian cancers. So far, studies show uterine cancer is the most strongly linked to hair relaxers.

What is the truth about hair relaxers? ›

They all contain lye, or sodium hydroxide, a versatile yet highly corrosive substance used in the manufacturing of many different products. Because hair relaxers contain lye, they can damage your hair and scalp if used incorrectly, and even cause hair loss.

Is there a lawsuit against hair relaxers and breast cancer? ›

Hair Relaxer Breast Cancer Lawsuits

If you were diagnosed with breast cancer after using chemical hair straighteners, you may be eligible for a chemical hair straightener breast cancer lawsuit. Call Marin and Barrett, Inc.

What is the controversy with hair relaxers? ›

Around the country, Black women have brought lawsuits against companies over the use of certain chemicals in hair relaxers and hair straighteners, claiming there's an increased risk of uterine cancer. A ban on those chemicals is under consideration by the Food and Drug Administration.

Is the hair straightener lawsuit real? ›

Is there a hair straightener class action lawsuit? Yes. Over 8,000 hair relaxer lawsuits against L'Oreal USA Inc and other companies have been consolidated into a multidistrict litigation (MDL) or class action lawsuit.

Which hair relaxers contain formaldehyde? ›

Hair Straighteners that Contain or Release Formaldehyde
Brand/ManufacturerProduct Name
Envy ProfessionalTrissola True Keratin Solution
Keratin ComplexKeratin Complex Smoothing Therapy
Keratin ComplexKeratin Complex Express Blowout
Keratin ExpressKeratin Express Plus Smoothing Treatment
19 more rows

What does hair relaxers do to your body? ›

Chemical hair relaxers contain endocrine-disrupting chemicals, which can disrupt the functions of the endocrine system (which includes the thyroid, ovaries, pancreas and adrenal glands) and affect hormone levels. These chemicals include phthalates and parabens, which can be found in relaxers.

Is any hair relaxer safe? ›

Some hair relaxers are safe. But particular products containing certain chemicals are not. The chemicals in question are: Formaldehyde.

Can you have healthy hair with a relaxer? ›

Can relaxers damage hair? Having relaxed hair isn't synonymous with damaged hair. It's possible to have healthy, thriving hair even if it is chemically treated, however, overprocessing the hair with additional chemicals like hair color, heat styling, and skipping regular trims can lead to damage.

What hair products are linked to breast cancer? ›

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.

Has anyone won a hair relaxer lawsuit? ›

As of March 2024, there have been no finalized settlements in the hair relaxer injury lawsuits. The litigation is still in the early stages, with cases being consolidated into multidistrict litigation and the pretrial and discovery processes ongoing.

Who qualifies for a hair relaxer lawsuit? ›

The use of chemical hair relaxers has recently been linked to serious illnesses, including uterine and endometrial cancer. If you or a loved one suffered from cancer after using a chemical hair relaxer, you may be eligible for compensation from a hair relaxer lawsuit.

What can I use instead of a relaxer? ›

Some of the non-toxic and safer alternatives that you can use to straighten your hair include:
  • Blow-drying. Rather than using a hair relaxer, blow-drying your hair might prove helpful. ...
  • Heat styling. ...
  • Keratin treatments. ...
  • Oil treatment. ...
  • Silicone cream.
May 12, 2023

How to relax hair without damaging it? ›

Before going through the relaxer process, here are a few things to do:
  1. Do not agitate the scalp. ...
  2. Base the scalp.
  3. Only Apply Hair Relaxer To New Growth. ...
  4. Follow Timing Instructions. ...
  5. Use Neutralizing Shampoo.
  6. Wait at least 6 to 8 weeks before relaxing again. ...
  7. Maintain a good hair routine.
Oct 21, 2022

Which type of chemical hair relaxer is the oldest and still the most common? ›

Sodium hydroxide relaxers are commonly called lye relaxers. They are the oldest and most common type of chemical hair relaxer used by salon professionals. Sodium hydroxide, also known as lye or caustic soda, is the active ingredient in lye- based relaxers.

Which hair treatment is harmful for hair? ›

Keratin treatment is not good for the health of your hair. It just makes your hair appear straighter and smoother, but it can be damaging. It has no therapeutic benefit,” says Dr Goel.

Is a Brazilian Blowout a cancer risk? ›

The bottom line. A Brazilian blowout can be harmful to your health and hair. One of its main ingredients is a known cancer-causing chemical, formaldehyde. Brazilian blowouts and other smoothing treatments also contain other chemicals that can cause side effects and allergic reactions.

What cancer therapy causes hair loss? ›

Chemotherapy is the type of cancer drug treatment most likely to cause hair loss. Complete hair loss is very unlikely with any other type of treatment. But some other cancer drugs can cause hair thinning. It is not possible to tell beforehand who will be affected or how badly.

Top Articles
Latest Posts
Article information

Author: Reed Wilderman

Last Updated:

Views: 6718

Rating: 4.1 / 5 (72 voted)

Reviews: 95% of readers found this page helpful

Author information

Name: Reed Wilderman

Birthday: 1992-06-14

Address: 998 Estell Village, Lake Oscarberg, SD 48713-6877

Phone: +21813267449721

Job: Technology Engineer

Hobby: Swimming, Do it yourself, Beekeeping, Lapidary, Cosplaying, Hiking, Graffiti

Introduction: My name is Reed Wilderman, I am a faithful, bright, lucky, adventurous, lively, rich, vast person who loves writing and wants to share my knowledge and understanding with you.