Keratin treatments are popular chemical applications that can make your hair straight, glossy, and frizz-free for months at a time. While the results can be hair-flippin’ fantastic, there are some serious health risks to keep in mind.

Here’s a deep dive into all the possible side effects of keratin treatments — plus a few of the best alternatives that offer similar, safer results.

stylist straightening client's hairShare on Pinterest
Drouk/Getty Images

Keratin treatments contain (you guessed it!) keratin. This protective protein is found in your hair, nails, and skin. It helps form fibers that make your hair healthy and strong.

The keratin used in beauty products is usually derived from animal parts, so these treatments aren’t typically vegan. They can also contain some not-so-nice ingredients that aim to bully your hair into cooperating, including some gnarly chemicals.

The big bad of this group is formaldehyde. This smelly, flammable gas can help keep your hair frizz-free for months on end. But it can also cause some pretty serious side effects.

On its own, keratin is generally safe to use as a cosmetic hair treatment. But the added chemicals can be a cause for concern. (We’re lookin’ at you, formaldehyde 😠 .) Here are the deets.

Formaldehyde is a known carcinogen

If your stylist uses a formula that contains formaldehyde, you could inhale or absorb this chemical through your skin during a keratin treatment.

Why is that concerning? Because formaldehyde’s a known carcinogen. That means it might increase your risk of cancer, according to the American Cancer Society.

Some stylists have reported respiratory issues

Formaldehyde isn’t just a potential cancer-causer. Frequent exposure in a salon might lead to temporary or chronic respiratory symptoms like:

  • wheezing
  • coughing
  • shortness of breath
  • changes in lung function

A 2018 research review reported two cases of hairdressers who developed asthma. Both were exposed to hair-straightening treatments containing formaldehyde in a salon setting. While we need more in-depth studies to show all the possible long-term effects, these initial findings are an important callout.

Keratin treatment side effects can range from mild to severe. Symptoms tend to depend on the concentration of formaldehyde and the type of exposure. Here are some possible side effects, according to the Occupational Safety and Health Administration:

  • Respiratory issues. Formaldehyde is bad news for your upper airways. Concentrations above 50 parts per million can cause fluid in your lungs or bronchial irritation. Even lower concentrations can cause chest tightness, wheezing, coughing, and a burning sensation in your lungs and nose.
  • Eye irritation. You have to be 10/10 careful when using formaldehyde near your eyes. Direct eye contact can cause scarring or clouding of the corneas or, in severe cases, blindness. But even if it doesn’t get in your eyes, it can still cause burning, redness, itching, and tearing 😢 .
  • Skin reactions. A mild burning sensation is pretty common during a keratin treatment. But some folks also experience allergic contact dermatitis, hives, and inflammation.
  • Tummy troubles. You should NEVER eat formaldehyde. Ingesting even a tiny amount can cause nausea, puking, and stomach pain. In severe cases it can also cause organ damage and death.
  • Pregnancy. Formaldehyde exposure may lead to fertility problems and increase the risk of miscarriage. So def talk with your doc before getting a keratin treatment if your eggo is preggo or if you’re trying.

Lots of products claim to be formaldehyde-free, but brands can get sneaky. Formaldehyde might be listed under a different name, such as:

  • formalin
  • methanal
  • methanediol
  • methyl aldehyde
  • methylene oxide
  • formic aldehyde
  • methylene glycol

You should also avoid preservatives that can release formaldehyde. Common culprits include:

  • quaternium-15
  • diazolidinyl urea
  • benzylhemiformal
  • imidazolidinyl urea
  • 5-bromo-5-nitro-1,3-dioxane
  • 2-bromo-2-nitropropane-1,3-diol
  • sodium hydroxymethylglycinate
  • 1,3-dimethylol-5,5-dimethylhydantoin (or DMDM hydantoin)

Not sure if the risks of keratin treatments outweigh the rewards? Before you decide whether it’s right for you, take a look at some safer options:

  • Japanese straightening. A fan fave in the early ’00s, thermal reconditioning has been making a comeback in recent years. And 👏 we 👏 are 👏 here 👏 for 👏 it 👏 . This chemical process can leave your hair straighter and shinier for up to 6 months. Unlike keratin treatments, it’s formaldehyde-free for real.
  • Tourmaline hair-smoothing treatment. This at-home hair-smoothing treatment can give you a salon vibe at a fraction of the cost. But the best part? No formaldehyde! Look for a 100 percent natural formula.
  • Hot oil treatment. Hot oil treatments are the bomb. They’re made with plant-based oils like coconut, almond, or olive. They work by sealing your hair cuticle, which can help strengthen and protect your luscious locks. They can also help reduce frizz and give your hair a glossy glow. Just be sure there aren’t any yucky add-ins or preservatives.

A keratin treatment is a chemical process that can calm curls for up to 6 months. It can also give your hair a glossy shine and reduce frizziness. While the results can be gorg, the health risks might not be worth it.

Most keratin treatment formulas contain formaldehyde, a known carcinogen. Side effects can range from mild skin irritation to respiratory issues like wheezing, chest tightness, and burning.

If keratin treatments aren’t your thing, you may want to try a natural alternative that can offer similar results, such as Japanese straightening, tourmaline hair-smoothing treatment, or hot oil treatment.