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Chemical Hair Straighteners

Consumer health data has linked chemical hair straighteners to an increased risk of certain hormone-related cancers, including uterine and breast cancers. As a result, individuals have filed multiple lawsuits against chemical hair straightener manufacturers, claiming they did not warn them about the cancer risks.

Last Modified: February 19, 2024
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How Chemical Hair Straighteners Work

Permanent hair straightening breaks up natural chemical bonds that form and hold human curls. Chemical hair straighteners enjoy wide appeal because they’re effective at turning curly hair into straight hair.

A protein called keratin makes up the structure of hair strands. Keratin has molecules known as sulfides. Sulfides can pair together to create a disulfide bond. As sulfide molecules reach toward each other to form disulfide bonds, the hair bends. The more the disulfide bonds in a strand of hair, the more it coils and curls.

Chemical hair straightening products, also known as hair relaxers, use various chemicals to dissolve disulfide bonds, altering the protein structure’s shape in the hair and straightening it. Chemicals in hair straighteners include:

  • Ammonium thioglycolate
  • Benzophenone-3
  • Cyclosiloxanes
  • Diethanolamine
  • Parabens, formaldehyde
  • Phthalates
  • Sodium hydroxide (lye)
  • Sodium thioglycolate
  • Triclosan

If used incorrectly or too often, these chemicals can cause long-term damage to hair and skin and increase the risks for other health issues, including cancer.

Is Chemical Hair Straightening Safe?

Chemical hair straightening comes with the potential for unsafe toxicity. Two recent medical studies show a connection between using chemical hair straighteners and a higher long-term risk of uterine cancer, breast cancer, fibroids and endometriosis. In the short term, harsh chemical solutions may irritate your scalp and damage your hair.

Side effects of chemical hair straighteners affect not only people who receive hair treatments but also the salon staff who apply them. For instance, formaldehyde is a known carcinogen. It can lead to significant breathing and lung problems. Unfortunately, even products labeled formaldehyde-free may contain chemicals that release formaldehyde when subjected to heat.

Parabens are chemicals routinely used in cosmetic hair care and skin care products. Shampoos, conditioners and other hair products often contain parabens because of their effectiveness against mold and fungi. However, excessive paraben absorption can interfere with hormone production and cause hormone dysfunction, affecting male and female reproduction. Girls going through puberty are particularly vulnerable to these effects.

Side Effects of Chemical Hair Straighteners Include:
  • Allergic reactions
  • Alopecia
  • Atrophied skin
  • Burned scalp and skin
  • Damage to the hair shaft
  • Discolored hair
  • Eczema
  • Frizzy hair
  • Inflamed scalp
  • Irritated and painful scalp
  • Loss of hair

A 2022 National Institutes of Health study found that the risk of uterine cancer was twice as high in women who used chemical straighteners more than four times a year compared to those who didn’t use them.

Another NIH study from 2019 found that women who used chemical hair straighteners have an increased risk of breast and ovarian cancer. Black women are also at higher risk because they’re more likely to use hair straighteners and, on average, use them more frequently.

Chemical Hair Straighteners and Cancer

Uterine cancer and breast cancer are the top two cancers linked to chemical hair straighteners. According to researchers, parabens, phthalates, formaldehyde and the toxic chemical DEHP are among the ingredients in relaxers that may cause cancer.

For example, a 2022 study found that women who receive chemical hair straightening more than four times a year have twice the risk of developing uterine cancer. The study, published in the Journal of the National Cancer Institute, presented the first epidemiological evidence linking chemical hair straighteners to uterine cancer and other cancers. Researchers followed nearly 34,000 women aged 35-74 from 2003-2009. Women, particularly Black women, had the highest risk.

Researchers conducted extensive follow-ups to detect other links, and found more. The use of permanents and straighteners during adolescence may be associated with a higher risk of premenopausal breast cancer. Adolescents, particularly girls aged 10-13, are at risk because of the potential exposure of breast tissue to the chemicals. However, the study didn’t find that other hair care products, such as dyes and solutions for perms and body waves, had the same cancerous effects.

Chemical Hair Straightener Lawsuits

Chemical hair straightener lawsuits are relatively new, and followed the release of the 2022 NIH study. Women who used straighteners and later developed uterine, endometrial and ovarian cancer have filed legal claims against product manufacturers, claiming they failed to warn consumers of the potential risks.

Defendants in the claims include manufacturers L’Oreal, Namaste Laboratories and Godrej Company, which makes Strength of Nature products. Plaintiffs allege these manufacturers predominately marketed to Black women who are more likely to use chemical hair straighteners. L’Oreal says it stands by the safety of its products.

Plaintiffs are requesting compensation for medical expenses, lost wages, pain and suffering. They also want the manufacturers held accountable. They claim the manufacturers knew, or should have known, that their chemical hair straighteners were defective and dangerous because they contained highly toxic compounds. However, they still manufactured, marketed and sold them.

Lawsuit Information
Women who used chemical hair straighteners and were diagnosed with uterine, endometrial and ovarian cancer are filing lawsuits.
View Lawsuits

There are about 275 lawsuits active in multidistrict litigation in Illinois federal court as of August 2023. More people who consistently used straighteners and were diagnosed with cancer are expected to add to the number of legal claims.

Those who used chemical hair straighteners and were diagnosed by a doctor with uterine, endometrial and ovarian cancer may qualify to file a chemical hair straightener lawsuit. A lawyer can help determine if someone qualifies and can help claimants obtain medical records to support their case.

Please seek the advice of a medical professional before making health care decisions.