Keratin treatments help smooth hair cuticles, giving hair a shinier appearance. They can also help your hair dry faster. But they’re also expensive and may contain potentially harmful ingredients.

A keratin treatment, sometimes called a Brazilian blowout or Brazilian keratin treatment, is a chemical procedure usually done in a salon that can make hair look straighter for as long as 6 months.

However, the treatment may increase health risks, including certain kinds of cancer, due to exposure to certain chemicals in the treatment.

If you’re not sure if keratin treatment is right for you, weigh the pros and cons below.

The body naturally makes the protein keratin. It’s what hair and nails are made up of.

The keratin in these treatments may be derived from wool, feathers, or horns. Certain shampoos and conditioners contain keratin, but you’ll typically get the most significant benefits from a salon treatment done by a professional.

The benefits of getting a professional keratin treatment or doing one at home can include:

Chemically straightened hair

A keratin treatment can make your hair look straighter for up to 6 months.

Smooth, shiny hair

It adds intense glossy shine to hair and can reduce frizz.

Keratin smooths cells that overlap to form hair strands, which means more manageable hair and less frizz. This results in hair that dries with little frizz and has a glossy, healthy look.

Keratin can also reduce the look of split ends by temporarily bonding the hair back together.

Some formulations can smooth curls, making them appear softer.

Thicker looking hair

Replenishing the keratin in your hair can cause it to look thicker.

Long-lasting results

If you care for a keratin treatment by not washing your hair too frequently (2 to 3 times a week is enough), your keratin treatment can last up to 6 months.

More manageable hair

Keratin treatments make hair more manageable, especially if your hair is particularly frizzy.

If you constantly heat style your hair, you’ll notice that a keratin treatment makes it dry more quickly. Some people estimate that keratin cuts their drying time by more than half.

Your hair may also become healthier and stronger because you can air dry it more often, preventing heat damage.

Hair growth

Keratin can strengthen and fortify hair so it doesn’t easily break off. This can make hair seem to grow faster because the ends aren’t breaking off.

A keratin hair treatment can have health risks.

Formaldehyde and formaldehyde-releasing chemicals

Many (but not all) keratin treatments contain formaldehyde, which can be dangerous if inhaled. It can cause symptoms such as:

  • headaches
  • dizziness
  • eye issues
  • sore throat
  • cough or wheezing
  • chest pain
  • nausea and vomiting
  • rash
  • kidney injury

Formaldehyde is what actually makes the hair look straighter.

According to the Food and Drug Administration (FDA), this chemical may be listed as:

  • formaldehyde
  • formalin
  • methylene glycol

Hazardous chemicals may release formaldehyde gas when heated.

A 2021 case study reported that a 13-year-old female experienced severe kidney injury due to formaldehyde in a keratin treatment product marketed as formaldehyde-free.

The FDA recommends reviewing the ingredients list and communicating with your stylist about the salon’s safety practices to limit formaldehyde exposure. They have also issued warning letters to brands whose products contained unsafe amounts of formaldehyde or did not disclose the presence of formaldehyde.

Alternatives to formaldehyde

More permanent straightening options like relaxers (sometimes called Japanese straightening) actually break hair bonds using the ingredients ammonium thioglycolate and sodium hydroxide. This makes for permanent results but can also cause an awkward growing-out phase, with non-treated hair growing curly at the roots. Some keratin treatments are formaldehyde-free (they use glyoxylic acid instead), but they’re not quite as effective.

Cancer risk

Research from 2019 linked chemical straighteners and breast cancer risk. Females in the study who used straighteners every 5 to 8 weeks or more often had a 31% higher risk of breast cancer.

Research from 2021 suggests a link between chemical straighteners and ovarian cancer. The researchers noted an increased risk of uterine cancer in females who used chemical straighteners more than four times a year.

Additional research from 2022 links chemical straighteners and uterine cancer. The researchers noted an 80% higher adjusted risk of uterine cancer in females who used a chemical straightening product within the previous 12 months.

Cost

Each treatment can range anywhere from $300–$800, plus tip. Less expensive at-home options are available, but the results do not last as long.

Make the most of the cost

Keratin treatments should be done no more than three times a year, as they can start to damage hair over time. People generally want to get them done in summer when the humidity makes frizz more pronounced.

Hard to maintain

Washing your hair less and avoiding swimming might make it harder for some people to maintain it.

  • The type of water on your hair matters: Swimming in chlorinated or salt water (basically a pool or an ocean) can shorten the life of your keratin treatment. You’ll also need to invest in shampoo and conditioner free of sodium chloride and sulfates, as these can strip the treatments.
  • Wait to wash: You’ll have to wait 3 to 4 days post-keratin treatment to get your hair wet, so if you don’t like skipping wash days, this treatment may not be right for you. Some people report a musty smell even after washing.
  • Not recommended for all: It’s not recommended for pregnant people.

Is keratin treatment good for your hair?

A keratin treatment can benefit your hair, including smoothing frizz, straightening, and giving hair a shiny appearance.

What is a keratin treatment, and how long does it last?

A keratin treatment is a chemical procedure that can make hair smoother and more manageable. It can last as long as 6 months.

What are the pros and cons of keratin?

Keratin treatments can make hair smooth and shiny and reduce the appearance of frizz. It can also help hair dry faster. However, the chemicals involved may have a negative effect on overall health, including increasing the risk of breast, cervical, and uterine cancers.

Keratin treatments can make frizzy, thick hair easier to manage. They can also reduce hair drying time.

The treatments are expensive, however, and the formaldehyde in many formulas can be dangerous if inhaled, so make sure you’re getting the treatment done in a well-ventilated area or choosing a formaldehyde-free formula.