Keratin Hair Treatments: Your Ultimate Guide

Bye, frizz.

a woman with smooth keratin treated hair looking into the distance
(Image credit: Getty Images)

It's hard to spin frizz as an overtly positive thing. The fact of the matter is that our hair doesn't love humidity. Air-dry creams and at-home keratin-infused products can calm styles down to a certain degree. Still, keratin hair treatments, also known as Brazilian blowouts, semi-permanently tame frizz and provide a silky and shiny texture to an extreme degree in just a few hours.

"These treatments can significantly cut down on styling and blow drying time so that they can be a major time saver," explains hairstylist Kee Taylor. However, getting a keratin treatment isn't a catch-all solution for everyone. Depending on the specific chemicals used and your hair type, it can damage your hair and your health.

To get all the information, I tapped top experts—and I even tried out a keratin treatment for myself, too.

What Is a Keratin Treatment?

Before we dive into keratin treatments, let's discuss keratin in general. Our hair is loaded with keratin: it's the fibrous protein that forms the main structure of our hair and is effective at blocking out humidity.

Over time, hair loses keratin from sun exposure, hot tools, and chemical processes like bleaching. "When the hair is depleted of proteins, it can look dry and lifeless. It also has a lot more frizz, tends to swell in humid weather, and is prone to not being protected from the sun and environmental damages, especially if it's been color-treated," shares Ebony Gordon, CEO of Hairista Studio.


A photo posted by sandrasflawlesshair on

A keratin treatment, on the other hand, replaces keratin in places where it has been depleted, adds trichologist and hair expert Shab Caspara. While additional keratin doesn't structurally change your hair, it can enhance it and strengthen it temporarily. "While the results can vary depending on the individual's hair type and the specific treatment used, many people find that their hair is significantly smoother, shinier, and easier to style after receiving a keratin treatment," Caspara adds.

Keratin Treatment Alternatives

"Keratin treatment" and "keratin smoothing treatment" are often used interchangeably, but they're technically different. Traditional keratin treatments, aka Brazilian blowouts or straightening treatments, straighten out your hair, while formaldehyde-free keratin smoothing treatments (like Cezanne, GK, or Kerasilk) aim to help you add shine and cut down on frizz without disrupting your hair's natural texture.

"A straightening treatment breaks the bonds of the hair so it is permanently straight or mostly straight and leaves a demarcation line during grow out," shares hairstylist Kennidi Wallgren. With a straightening treatment, your hair is coated in the keratin solution to break down bonds before it's blow-dried and straightened with a high-heat tool to seal it back up. In the end, your hair is frizz-free and straight. "[These] are traditional keratin treatments known to last longer and smooth the hair out more," explains Caspara. "They contain chemicals known as aldehydes which help bond the keratin to the hair."

Curly-haired Shakira smiles on stage at night during a performance.

Reminder: Don't let anyone talk you into getting rid of your natural texture if you don't want to. Shakira's gorgeous frizz is part of what makes her hair so good.

(Image credit: Getty Images)

A smoothing treatment, meanwhile, is usually marketed as formaldehyde-free. It won't completely straighten your hair (you'll keep a bit of your curl pattern), but it will make it sleek and frizz-free. With less harsh ingredients, this is a good option for those with allergies or scalp sensitivities.

No matter what look you're going for, Gordon is wary about any product that uses the inclusion of keratin as a selling point. "The ingredients [can be] similar, even though the function is designed for something different," she shares. Take this as your warning to know exactly what you're getting yourself into with any kind of treatment. Have a full consultation with your stylist and do your own research, too.

Are Keratin Treatments Safe?

The most controversial aspect of a keratin treatment is that the composition frequently includes formaldehyde, which the FDA is looking to ban. A carcinogenic chemical, the safety of formaldehyde in chemical straighteners was majorly called into question in December 2022, when a study showed that women who regularly use formaldehyde-containing products more than double their risk of endometrial cancer. (It's important to note that despite this statistic, the rate of endometrial cancer remains very low.)

Frequent exposure to formaldehyde can also cause respiratory problems, with the CDC also noting that "exposure to formaldehyde can irritate the skin, throat, lungs, and eyes."

Meghan Markle with smooth straight hair, walking away from a car.

Meghan Markle is famously a fan of keratin treatments.

(Image credit: Getty Images)

While the label "formaldehyde-free" is often touted in keratin smoothing treatments as a much safer alternative, you still need to be wary. Formaldehyde isn't just an ingredient you can control+find on a list; it's a gas that's released when other chemicals are exposed to heat. “To identify products containing formaldehyde-related ingredients, look for the following words on the label: Formaldehyde, formalin, and methylene glycol," explained medical researcher Alexandra Arriaga while discussing the best at-home keratin treatments with Marie Claire.

What Should I Expect From a Keratin Treatment?

"The treatment typically begins with a clarifying shampoo to get rid of any product buildup in your hair. Then, the hair must be fully blow-dried. Next, the keratin formula is applied to the entire head in small sections to ensure each strand is coated," explains Taylor. "This step is followed by another blow dry that must render the hair 100 percent dry." Once dry, the hair is flat ironed at a high temperature, until each section is completely straight.

In the end, even the tightest curls can lose their bounce. But there is a possibility you'll still have a slight wave, especially with smoothing treatments. Based on porosity and application, some hair responds better to treatment than others.

How Long Does a Keratin Treatment Take?

The first thing to know about an in-salon keratin treatment is that it takes a long time, regardless of whether you're doing a straightening or a smoothing treatment. It can take roughly two to three hours, but it could easily take five hours or longer, depending on your hair's length and texture.

Writer Sophia Vilensky's hair before and after an in-salon Cezanne keratin treatment.

The left photo shows natural, wavy hair. The right photo shows results directly after a Cezanne treatment.

(Image credit: Sophia Vilensky)

Keratin Treatment Aftercare

With a true keratin treatment or Brazilian blowout, you need to stay away from water for 72 hours and keep your hair down so it doesn't dent. "I know it may be hard to completely avoid getting your hair wet for three full days, so I recommend getting a reusable shower cap," says Taylor. "To prolong the life of your keratin treatment, be sure to use a paraben and sulfate-free shampoo and conditioner. If your hair does come into contact with water during those 72 hours, don't panic! Just dry and straighten the area that got wet."

There are, however, some treatments that don't require you to skip the shower. "The best part of Cezanne's Keratin Smoothing Treatment is that there is no downtime. You can immediately resume your lifestyle, wear a ponytail, clip it up, shampoo…..anything you want!" says Wallgren.

My Keratin Treatment Experience

I was wary about getting a keratin smoothing treatment because my hair is fine and only has the slightest texture (on a good day). Why would I risk losing the little volume I have? That said, I eventually settled on a Cezanne treatment—for the story.

After a thorough consultation with Wallgren, the three-hour process went exactly as Taylor had described. While it was a long time to spend in a chair, I recently heard it took Zendaya's stylist *nine hours* to make her hair honey blonde, so I cannot complain.

Sophia Vilensky after a Cezanne treatment.

Me, at 9 p.m. after a keratin treatment, in my sweats with perfect hair.

(Image credit: Sophia Vilensky)

After a final wash, I was blown away by how fast my hair dried—and how sleek it looked with no product or styling. Since my appointment, I've made everyone I know run their fingers through it. While I know the true test will be the summer's humidity, I have a good feeling about where things are headed. Maybe, for once in my life, I won't be so...scraggly?

Still, I will once again say that this was my experience. You (and your hairstylist!) will know what's best for your hair.

At-Home Keratin Treatments

While at-home keratin treatments don't last nearly as long as their in-salon sisters, they're a great choice if you want to go a more affordable (yet still smoothing) route.

"Styling products containing keratin that can be used daily to manage hair can [also] be really effective," shares Caspara. "A great example is the Its’ a 10 Miracle Leave-in Potion Plus Keratin which contains hydrolyzed keratin and panthenol to smooth and moisturize strands to preserve straight styles while resisting humidity."

Meet the Experts

Kee Taylor's headshot.
Kee Taylor

Annagjid (Ahh-nah-key) Taylor, also known as “Kee” who got her start in her Mom and Dad's basement is now a CEO, author, Editor in Chief, salon owner, and hairstylist, not only in her own salon but in the entertainment industry as well.

Kee's hair salon ‘Deeper Than Hair’ is based in West Philadelphia and just celebrated 10 years in business. Her salon is most known for their attention to the health of the client’s hair and getting damaged hair to its strongest state. Because of her dedication to caring for the health of her client's hair and feeling like something was missing from the industry, Kee was inspired to create an advanced hair care line, ‘Shear Genius Collection’. She also has taken initiative to build up the youth with her children's book, All Hair is Good Hair, which is available at Barnes and Noble and Amazon.

Shab Caspara
Shab Caspara

Born in Iran and raised in Toronto, Canada, Shab Caspara grew up in the environment of her mother’s hair salons and hair schools from a young age. After a fulfilling career as an award-winning hairstylist in New York City, today she is one of the most recognized trichologists and an expert source for all major beauty and health media outlets. Shab is featured in a multitude of publications for her expert knowledge on hair and scalp health, hair care, consumer trends and scientific research.

Shab is the founder of the first tech-enabled hair care retail platform matching women to the best hair growth solutions and devices from around the world. She has consulted as a hair health advisor for the relaunch of HairClub and hair brands including Inkey List, Augustinus Bader, Tangle Teezer and Hairmax.

Shab is a trained trichologist through the United States Trichology Institute and is a member of the American Hair Loss Council.

Kennidi Wallgren Headshot
Kennidi Wallgren

Growing up in a family of stylists fueled Kennidi Wallgren's lifelong dedication to the hairstyling world. Fashion and beauty inspire her deeply, and she thrives on unleashing her creativity across various hair types and styles. It’s a genuine privilege for her to contribute to someone’s inner and outer beauty, ensuring that each client leaves feeling truly amazing. As a Surface Educator, she finds immense joy in sharing her knowledge with fellow stylists, while also serving as a mentor to nurture the skills of budding talents within her salon.

Ebony Gordon Headshot
Ebony Gordon

Ebony Gordon is an expert on natural/curly hair, color, extensions, and overall hair health. With 10+ years of experience, Ebony has served thousands of clients in the salon and at home through her Hairista Essentials product and healthy hair tips through her content.

headshot of Alexandra Arriaga
Alexandra Arriaga

Alexandra Arriaga is a science based haircare and beauty chemist, MPH, medical researcher based in New York.

Sophia Vilensky
Freelance Writer

Sophia Vilensky is a Freelance Beauty Writer at Marie Claire with a beauty, wellness, and entertainment journalism portfolio that includes contributions to Byrdie, Bravo, Teen Vogue, and Us Weekly. Growing up in a family of beauticians—and through her own personal studies—she developed an in-depth understanding of aesthetics, cosmetic product formulation, and beauty treatment development and has also held roles as a senior copywriter, content strategist, and proofreader for top beauty and wellness brands. Even so, you'd be hard pressed to find her with her hair and makeup actually done. Sophia is based in Minneapolis and is a 2019 graduate of the University of Minnesota, where she majored in English and minored in cinema studies. During her time at the university, she was the Arts & Entertainment Editor for the Minnesota Daily, earning the 2019 Editor of the Year award for her work. She connected deeply with the Twin Cities arts scene, collaborating with leading beauty professionals, designers, and artists. Graduating Summa Cum Laude, her thesis—a close-reading of Vanderpump Rules—was featured on NPR. When not immersed in writing or testing new products, Sophia enjoys watching reality TV, reading, and exploring the newest woo-woo wellness trends. Keep up with her on Instagram @sophiavilensky.