Are your beauty choices killing you slowly? As dramatic as that question sounds, there are ingredients in certain hair products that are dangerous to your health—especially hair straighteners. Discover what ingredients to watch out for, their negative effects, and which straightening solutions can provide great results without the health risks.
Contents:
What is Hair Straightening?
Hair straightening is a chemical process that works to smooth the hair by reducing or removing the curl or wave patterns of your hair’s natural texture. Depending on the straightening service you choose, results typically last between 6 weeks and six months.
Whether you want smoother hair for aesthetic reasons or you’re sick of battling frizz and tangles, hair straightening is very effective when done correctly. It can make hair softer and smoother, add shine, and make styling easier—no wonder it’s such a popular service.
There are several straightening options and techniques available, ranging from semi-permanent to permanent. As the name implies, permanent straightening treatments last the longest, though .
The Dark Side of Hair Straighteners
You know the saying, “beauty comes with a price?” We often joke about it in terms of sacrificing comfort or the cost of services. But the sad truth is, some beauty services and products come at a much higher price than others.
Numerous studies over the years have shown that there truly is a dark side to chemical hair straighteners. Specifically, certain straighteners have been linked to the dreaded C word: cancer.
One study featuring over 46,000 women found a definitive link between straighteners and breast cancer¹, and concluded that women who chemically straightened their hair regularly were 30% more likely to develop breast cancer than those who didn’t.
Another study of 33,497 women also found hair straighteners are linked to a higher risk of uterine cancer². The data suggests approximately 1.4% of women who don’t get straighteners will develop uterine cancer eventually, but that chance more than doubles (4.05%) for women who do get them.
Nearly 10,000 lawsuits are pending³ against several companies for failure to warn customers of the hazardous chemicals in its hair relaxer products. L’Oreal, SoftSheen-Carson, Strength of Nature, Paul Mitchell, and Revlon are among the defendants.
What is the Cause of Cancer Risks in Hair Straighteners?’
The correlation between cancer and straighteners is the ingredients lurking within and the frequency and duration of the service.
Some of the most notable culprits will likely sound familiar to you due to their known or potential toxicity to the human body.
Formaldehyde I hate to sound like Captain Obvious here, but we all know what this is. Formaldehyde is used to help preserve and sanitize dead bodies. And while it occurs naturally in the body in low amounts, it has no business in beauty products. Formaldehyde’s been linked to cancers resulting from hair straighteners, leukemia, and nasal cancers. Studies have also found it to cause serious, long-term health issues for mortuary attendants⁴ without the use of proper protective gear. Despite this, it’s used as a preservative in cosmetics, it’s added to building materials, and can also be found in common household products, among other things. There are also certain chemicals in products that can create a gas form of formaldehyde⁵ during certain processes that require heat, even if it doesn’t contain it. I’m no scientist, but I believe common sense comes into play here: What happens naturally in our bodies isn’t the problem. It’s the addition of formaldehyde in all these different types of products and levels of exposure that make this chemical so harmful. A proposal to ban formaldehyde and formaldehyde-releasing chemicals was introduced in Spring 2023, but has been pushed back several times. The last update rule stage was in Fall of 2024⁶. As of October 2024, the FDA has issued warning letters⁷ to Brazilian Blowout (GIB), and Van Tibolli Beauty Corp for safety and labeling violations. The FDA does claim both companies took steps to correct the violations, but it’s uncertain what steps they took and if it’s fully resolved.
Parabens A type of preservative, parabens are used in cosmetics, drugs, and even food. Awesome, right? These chemicals are linked to increased risks of breast cancer and the disruption of the endocrine system⁸. That said, they are FDA approved. Parabens do, in fact, ward off bacteria, mold, and fungus, and they naturally occur in certain fruits and vegetables in low levels. The same thing as formaldehyde applies here: It’s not the levels at which parabens naturally occur that are the problem. It’s when they’re added to a bunch of different products. Who knows how many personal care items we use that contain them, or food with added parabens we consume on a daily basis.
Bisphenol A (BPA) This chemical is what’s used to make plastics and resins. BPA has been linked to immune disorders, neurological issues, sexual, and child development⁹. It’s also found to be an endocrine disruptor. Similar to formaldehyde and parabens, the biggest issue with BPA is thought to be mass exposure through cross contamination from packaging and plastics into foods or hair and skin products. This is why you see so many plastic products that advertise as being BPA-free. While BPA is typically found only in cosmetic packaging and not as an actual ingredient, it has been found in some chemical hair straightening products².
Cyclosiloxanes As they are conditioning chemicals, cyclosiloxanes are often used in hair straighteners to improve conditioning and spreadability—including straightening kits recommended for children¹⁰. Exposure to cyclosiloxanes are linked to uterine cancer and damage to the reproductive system. Studies have also found cyclosiloxanes produce fatal liver and lung damage in female mice¹¹.
Di(2-ethylhexyl) phthalate (DEHP) This chemical is more commonly known as phthalates and is used as a fragrance carrier. While phthalates are synthetic, they are found in some plants, fungi, and algae. DEHP specifically, is a plasticizer used in food packaging and PVC. Phthalates are known to cause birth defects, cancer, and be harmful to the reproductive system, and have been found in some hair straighteners¹². All that said, it boils down to exposure levels. Too much of anything is bad—even chocolate. Phthalates are FDA approved for food packaging, but not for cosmetics. They do monitor levels of phthalates in cosmetics¹³, however, but claim there is no evidence to support a safety risk at this time.
Lye (sodium hydroxide) Lye is the main ingredient in many relaxers. It’s not a carcinogen, but it can cause severe burns to the eyes, scalp, and skin, and has been known to cause dermatitis and permanent lung damage from prolonged exposure. It’s also damaging to the hair due to its highly corrosive nature.
Aftermath of Hair Straightening Treatments: Other Risks and Considerations
There’s a common misconception that the risk of chemical exposure from some hair straightening treatments are over after the service is complete.
Unfortunately, this just isn’t true.
For example, every time you heat-style your hair, you’re releasing those chemicals as you are essentially processing your hair. In fact, any PH changes to your hair, whether from the sun or even water, have the same effect. This is because the chemicals used in many straighteners wear off and “react” to changes that occur during styling or your environment.
Does That Mean You Have To Stop Straightening Your Hair?
Whether you should stop straightening your hair is a very personal decision and one we can’t make for you.
That said, knowledge is power.
And the good news is, there are safer alternatives to hair straighteners with questionable or harmful ingredients. To make the most informed decision, you’ll need to know the difference between the hair straighteners available.
Different Types of Chemical Hair Straighteners
While chemical hair straighteners aim to offer similar results, the techniques and products used are different. All types of straighteners are, as the name implies, meant to make the hair straighter, smoother, and softer. The ingredients and how they work are what most sets them apart.
Hair Relaxers
A relaxer is a straightening technique that smooths the hair by breaking the hair’s natural bonds, which significantly alters your hair’s natural structure. It’s one of the harsher straighteners and opens repeat users up to a significant amount of chemical exposure. Several hair relaxer manufacturers are in current lawsuits due to their link with uterine cancer.
Long-term effects:
Frizzy hair
Thinning hair
Breakage and split ends
Hair loss
Dandruff
Graying
Increased risk of hormone-related cancers
Keratin Treatments
Keratin treatments are formulated to reduce frizz, make hair smoother, and cut down on blow-drying time for up to six months. While gentler than some of the other straightening techniques, Keratin treatments can still be damaging to the hair and cause permanent changes to the hair’s curl patterns.
Many Keratin treatments also contain formaldehyde and can also be an allergen to people with sensitive skin.
Long-term effects:
Skin and eye irritation
Dryness, brittleness, and split ends
Hair loss
Potential health concerns from formaldehyde or formaldehyde-inducing chemicals
Brazilian Blowout
A Brazilian Blowout is a popular semi-permanent straightening method that temporarily smooths the hair for up to 12 weeks. Rather than sealing keratin protein into the hair, it coats the hair. This means it also washes out faster and requires more frequent treatments, which can lead to your hair being overloaded with protein. Too much protein in the hair can cause damage.
Long-term effects:
Breakage
Loss of natural hair texture
Potential health concerns from formaldehyde or formaldehyde-inducing chemicals
In 2012, GIB LLC DBA Brazilian Blowout was ordered to stop deceptive practices¹⁴ and pay $600,000 in penalties. They have since launched a formaldehyde-free version, though it is still controversial, as some claim that the formula contains chemicals that, when paired together, create formaldehyde, which can then be inhaled during processing.
Japanese Thermal Straightening
This straightening technique breaks down the bonds in the hair to make it smoother and then uses a flat iron to achieve straight, sleek hair. However, Japanese Thermal Straightening doesn’t just wash out. It stays straight, while your roots grow out curly or textured, which requires heat styling.
Some claim this technique has permanently damaged their hair and even changed their natural hair growth forever. There are different strengths for this straightener, so it’s important to see a skilled beauty professional to prevent as much damage to your hair as possible.
Long-term effects:
Breakage
Hair loss
Permanent loss of curl pattern
Allergic reactions
Excessive hair shedding
Hair Rebonding
Hair rebonding is a permanent straightening treatment meant for exceptionally curly or frizzy hair. Rebonding alters your hair structure permanently. Because it breaks the hydrogen bonds in your hair apart and then puts them back together¹⁵, it can make hair smoother than most straightening treatments. However, it also has more potential for damaging the hair.
Long-term effects:
Breakage
Dryness
Hair loss
Scalp irritation
Loss of natural curls
Potential health concerns from formaldehyde or formaldehyde-inducing chemicals in some formulas
At-Home Perms
There are also at-home perm options for straightening your hair. We strongly recommend against using these products.
You might be thinking, of course you would, you’re a hair salon.
Yes, that’s true. But here’s the thing. Professional straightening treatments can damage the hair. The risk of this is even greater when using a home straightening product. It might save money at first, but could end up leading to costly repair treatments down the line—and it will never give you “salon” results.
Long-term effects:
Significant hair damage
Dryness
Breakage
Scalp irritation
Hair loss
Potential health concerns from formaldehyde or formaldehyde-inducing chemicals in some formulas
Peter Coppola Keratin Smoothing Treatments
Not to be confused with regular Coppola Keratin treatments, Peter Coppola Keratin Smoothing Treatments offer a safer alternative to straighteners while still providing excellent results. And it’s what we use here at Alkali.
Peter Coppola Keratin Smoothing Treatments are highly customizable and can be tailored to meet a variety of desired outcomes. It tames your curl pattern, and reduces frizz and curl up to 85% while still maintaining volume and versatility in the hair. It also nourishes and repairs the hair and provides a protective barrier from the harmful effects of UV exposure, processing, and heat styling thanks to its unique a-Keratin Repair System.
With Peter Coppola Keratin Smoothing Treatments, your hair will be smoother, softer, and healthier. You’ll also enjoy faster styling times and easier manageability for at least three months with minimal, if any, damage when done by a skilled professional. This treatment is safe for all hair types and can be applied from age 12 and up.
The Key Ingredients of Peter Coppola Keratin Smoothing Treatments are:
Keratin
Glyoxyloyl Keratin Amino Acids
Helianthus Annuus (Sunflower) Seed Oil
Butyrospermum Parkii (Shea) Butter
Formaldehyde-Free, aldehyde free, Gas Byproduct-Free, & Non-Carcinogenic
Key Considerations: Stylist Education (or Lack thereof)
If you’ve had a bad experience with a Peter Coppola Keratin Smoothing treatment, it likely stems from a stylist not truly understanding the science of hair, their inability to properly determine the health of your hair, or worse, sheer negligence.
Sadly, some stylists will perform a hair service even when they know full well it will damage the hair for fear of losing the client. At Alkali, we take hair health just as serious as we do our work. Our stylists are trained to never perform a service that they suspect will lead to damage or further damage to your hair.
Protecting Your Hair is All About Knowing Your Options
While there is a dark side to hair straighteners, there is a light at the end of the tunnel. You can still get smoother, shinier, and easier to manage hair without all the negative effects. The important thing is education. Knowing your options, potential side effects, and choosing a knowledgeable stylist will ensure you get the most benefits of whatever treatment you choose.
Thinking about straightening your hair? Schedule a free consultation to see how Peter Coppola Keratin Smoothing Treatments can help you tackle frizz, tame curls, and give you smoother, shinier, and healthier hair.
Sources:
¹ Eberle, Carolyn E., et al. “Hair Dye and Chemical Straightener Use and Breast Cancer Risk in a Large US Population of Black and White Women.” International Journal of Cancer, 3 Dec. 2019, https://doi.org/10.1002/ijc.32738.
² National Institutes of Health. “Hair Straightening Chemicals Associated with Higher Uterine Cancer Risk.” National Institutes of Health (NIH), 17 Oct. 2022, www.nih.gov/news-events/news-releases/hair-straightening-chemicals-associated-higher-uterine-cancer-risk.
³ “Hair Relaxer Cancer Lawsuit: July 2024 Update.” Drugwatch.com, www.drugwatch.com/legal/hair-straightener-lawsuits/.
⁴ Akortiakumah, John Kwasi, et al. “A Qualitative Exploratory Study on the Effects of Formalin on Mortuary Attendants.” SAGE Open Medicine, vol. 10, Jan. 2022, p. 205031212211312, https://doi.org/10.1177/20503121221131216.
⁵ “FAQs «Hair Straighteners.” Ewg.org, 2025, www.ewg.org/hair-straighteners/our-report/faqs-7/. Accessed 31 Jan. 2025.
⁶ “View Rule.” Reginfo.gov, 2024, www.reginfo.gov/public/do/eAgendaViewRule?pubId=202410&RIN=0910-AI83. Accessed 31 Jan. 2025.
⁷ Nutrition, Center for Food Safety and Applied. “Hair-Smoothing Products That Release Formaldehyde When Heated.” FDA, 8 Sept. 2020, www.fda.gov/cosmetics/cosmetic-products/hair-smoothing-products-release-formaldehyde-when-heated.
⁸ Hager, Emily, et al. “Minireview: Parabens Exposure and Breast Cancer.” International Journal of Environmental Research and Public Health, vol. 19, no. 3, 8 Feb. 2022, p. 1873, https://doi.org/10.3390/ijerph19031873.
⁹ Erler, Cheryl, and Julie Novak. “Bisphenol a Exposure: Human Risk and Health Policy.” Journal of Pediatric Nursing, vol. 25, no. 5, Oct. 2010, pp. 400–407, www.sciencedirect.com/science/article/abs/pii/S0882596309001407, https://doi.org/10.1016/j.pedn.2009.05.006.
¹⁰ Helm, Jessica S., et al. “Measurement of Endocrine Disrupting and Asthma-Associated Chemicals in Hair Products Used by Black Women.” Environmental Research, vol. 165, 1 Aug. 2018, pp. 448–458, www.sciencedirect.com/science/article/pii/S0013935118301518#s0120, https://doi.org/10.1016/j.envres.2018.03.030.
¹¹ Lieberman, Michael W, et al. “Cyclosiloxanes Produce Fatal Liver and Lung Damage in Mice.” Environmental Health Perspectives, vol. 107, no. 2, 1 Feb. 1999, pp. 161–165, www.ncbi.nlm.nih.gov/pmc/articles/PMC1566344/, https://doi.org/10.1289/ehp.99107161. Accessed 19 Jan. 2024.
¹² “Study Reports Association between Hair Straightener Use and Uterine Cancer: A Risk Assessment Is Needed – Paustenbach & Associates.” Paustenbachandassociates.com, 2022, paustenbachandassociates.com/2022/11/10/study-reports-association-between-hair-straightener-use-uterine-cancer-risk-assessment-needed/. Accessed 31 Jan. 2025.
¹³ FDA. “Phthalates in Cosmetics.” FDA, 19 May 2022, www.fda.gov/cosmetics/cosmetic-ingredients/phthalates-cosmetics.
¹⁴ “Attorney General Kamala D. Harris Announces Settlement Requiring Honest Advertising over Brazilian Blowout Products.” State of California - Department of Justice - Office of the Attorney General, 30 Jan. 2012, oag.ca.gov/news/press-releases/attorney-general-kamala-d-harris-announces-settlement-requiring-honest. Accessed 31 Jan. 2025.
¹⁵ Watson, Kathyrn. “What Is Hair Rebonding and Does It Work?” Healthline, Healthline Media, 2 Nov. 2020, www.healthline.com/health/beauty-skin-care/hair-rebonding#how-it-works. Accessed 31 Jan. 2025.