Are Keratin Treatments Bad for You?

The scary unknown side effects you need to know.

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Keratin treatments—aka the six-month-long blowout—are now a heavily debated topic. They were super popular at first because they actually worked. “People get keratin treatments to retain some of the curls and get rid of frizz,” says hairstylist Nunzio Saviano. But after finding out these treatments contain harmful chemicals, people have been wary of whether they were worth getting or not.

We asked both Saviano and Glamsquad Creative Director Giovanni Vaccaro for their input on the dangers of keratin treatments and whether or not we had to give them up for good. Luckily for those keratin-treatment loyalists, their answer was no. "I wouldn't say [keratin treatments] are necessarily bad for your hair," says Vaccaro. "There are different brands of keratin, and it's important to know what kind you're using and how frequently you're getting it done." We had them break it down in more detail for us.

Below, read about the negative effects keratin treatments can have on your hair and what you can do to avoid them.

Meet the Expert

  • Nunzio Saviano is a New York-based, award-winning hairstylist and owner of the Nunzio Saviano Salon. 
  • Giovanni Vaccaro is the Artistic Director at Glamsquad. 

What is Keratin?

Keratin is a protein naturally found in our hair, skin, and nails that keeps them strong and healthy while preventing breakage.

Are Keratin Treatments Safe?

Both Vaccaro and Saviano say keratin treatments that contain formaldehyde, the chemical that keeps hair frizz-free and straight for months at a time, are the treatments to be wary of. As defined by the Centers for Disease Control and Prevention (CDC), formaldehyde is a colorless, strong-smelling gas. In 1987, the U.S. Environmental Protection Agency classified it as a substance that could potentially cause cancer after prolonged exposure. Saviano suggests looking at reputable salons that offer formaldehyde keratin treatments at a safe percentage (anything below 0.002% is good) or salons that offer keratin treatments with formaldehyde alternatives.

Consult with a stylist you trust before trying out a keratin treatment.

Can Keratin Treatments Cause Allergic Reactions or Respiratory Problems?

The CDC lists common side effects to formaldehyde exposure such as sore throat, nose bleeds, and scratchy eyes. In an interview with Glamour, Wynne Sisk, a hairstylist from Charleston, South Carolina, said she experienced heaviness in her chest and headaches that would last for several days when giving clients keratin treatments. In 2016, the Environmental Working Group (EWG) and Women’s Voices for the Earth sued the Food and Drug Administration for failing to regulate the use of formaldehyde.

Alison Czinkota/Byrdie

“For years, stylists have reported that the application of these hair treatments caused difficulty breathing, eye irritation and nosebleeds,” said Tina Sigurdson, EWG assistant general counsel, in a press release about the lawsuit. “The FDA has been aware of the health hazards associated with the products since at least 2008.” However, it's crucial to note that these issues have mostly been reported among stylists; salon customers don't typically experience as strong reactions, unless there is an allergy.

Is There a Risk of Hair Breakage and Increased Exposure to Formaldehyde When Using Keratin?

According to Saviano, you should pay attention to how much heat is applied to hair when getting a treatment. “If too much heat is applied or they over-straighten your hair, it will dry out your hair faster than normal and cause breakage,” he says. This would be caused by the stylist either using a temperature setting that is too high for your hair type, or running the iron through your hair too many times.

The temperature your stylist uses when flat ironing your hair will be dictated by a few factors, such as your hair texture, how much curl reduction you're seeking, and whether or not your hair is color treated. Someone with finer, straighter hair will require much less heat than someone with thick curly or coily hair. Make sure to find a stylist who is an expert at applying keratin treatments to hair with your texture and specific needs.

“The high temperature of the flatiron to seal the chemical into the hair is bad if you have existing damage to your strands,” says Vaccaro. “On top of that, when heat is applied to the hair, it releases formaldehyde into the air and those around end up inhaling it.” Make sure to go to a well ventilated salon if you're getting a keratin treatment that contains formaldehyde.

Ask your stylist about 100 percent formaldehyde-free versions of the keratin treatment, but also be sure to do your research before placing the chemical treatment on your hair.

The Final Takeaway

As mentioned before, there are now alternatives to formaldehyde in some keratin treatments. These offer the same smooth texture, but the hair is locked into place with glyoxylic acid. Ask your stylist if they have brands like Goldwell Kerasilk or Trissola Solo, which are 100 percent formaldehyde-free.

Another salon option is Keratin Complex. The company offers a few different formulas, from a classic smoothing treatment to one for fragile hair. These are actually designed to repair damaged hair, not straighten it. Still, that alone could help tame your frizz without the cost or risks involved with straightening.

Now that you have all the facts about keratin treatments, you can make smarter decisions when looking into getting one. Saviano says that if you go to well reputable places and do your homework on what ingredients salons use, you should be fine.

“Always consider the type and texture of your hair [and] your daily maintenance (other chemicals you are already using—color, single process, etc.),” says Vaccaro. “Make sure to communicate everything clearly with your stylist.”

As you weigh the pros and cons, here are a couple of hair-smoothing products that we’re currently loving.

Nunzio Saviano Anti-Frizz Sheets - Keratin Treatment Side Effects
Nunzio Saviano Anti-Frizz Sheets $18.00

Have an event or job interview? Keep one of these coconut oil-infused anti-frizz sheets on hand to smooth out frizz on the run.

Oribe Imperméable Anti-Humidity Spray - keratin-treatment-side-effects
Oribe Imperméable Anti-Humidity Spray $42.00

After you’re done styling your hair, spritz this "Miami-tested” spray on to keep your hair smooth and frizz-free all day. 

Farewell Frizz blow dry perfection & heat protectant crème
Briogeo Farewell Frizz Blow Dry Perfection Heat Protectant Crème $24.00

If you're a curly girl, use this rosehip, argan, and coconut oil-based crème as the last step before you diffuse or blow dry your hair for frizz and heat protection.

Kiehl's Silk Groom Serum
Kiehl's Silk Groom Hair Styling Serum $18.00

You can thank the emollients in the sesame oil and ceramides in the sunflower oil for hydrated, frizz free hair no matter your hair type.

  • What should you look for on the label to avoid keratin treatment side effects?

    Some products will claim to be formaldehyde-free, however will have this chemical listed on the label under a different name. Other names for formaldehyde include Formalin, Formic aldehyde, Methanediol, Methanal, Methyl aldehyde, Methylene glycol and Methylene oxide.

  • What is the difference between a keratin straightening treatment and keratin-infused products?

    A keratin straightening treatment, such as the Brazilian Blowout,  is done in the salon and uses chemicals to straighten the hair for up to six months. Keratin-infused products, such as shampoo or conditioner that you buy at the store, contain keratin protein and are safe to use daily as they don’t contain the same chemicals, such as formaldehyde, that keratin straightening treatments do. Keratin-infused products have more of a temporary effect on the hair, versus the long-term straightening effects of a treatment at the salon.  It is important, however, to always read the labels to ensure that formaldehyde (or any of the alternative names listed above) aren’t in the keratin-infused products. 

  • What are some safe keratin treatment alternatives?

    You can get smooth and shiny hair without the side effects of salon keratin treatments by considering some alternatives, such as Japanese Hair Straightening. You can also use a flat iron to get the smooth and sleek look— just make sure you use a heat protectant to protect your hair. Hot oil treatments can also deeply moisturize to give you healthy and sleek hair, without the harmful side effects of keratin treatments. 

Article Sources
Byrdie takes every opportunity to use high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial guidelines to learn more about how we keep our content accurate, reliable and trustworthy.
  1. Cleveland Clinic. Skin. Updated March 17, 2016.

  2. Centers for Disease Control and Prevention. Formaldehyde. Updated October 30, 2019.

  3. United States Environmental Protection Agency. C-FERST issue profile: formaldehyde. Updated March 19, 2019.

  4. Environmental Working Group. Lawsuit urges FDA to protect salon workers, consumers from formaldehyde. Updated December 14, 2016.

  5. Boga C, Taddei P, Micheletti G, et al. Formaldehyde replacement with glyoxylic acid in semipermanent hair straightening: a new and multidisciplinary investigationInt J Cosmet Sci. 2014;36(5):459-470. doi:10.1111/ics.12148

  6. American Cancer Society. Formaldehyde.

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