Can Keratin Damage Your Hair?

Medically Reviewed on 7/14/2021
can keratin damage hair
Keratin treatments can make your hair smooth and shiny in the short term, but they can also damage your hair if done too frequently

If you have ever struggled with frizzy hair, you may have been intrigued by keratin treatments that promise to make your hair smooth, shiny, and strong. But can it do more harm than good?

Keratin treatments often involve administering heat to open the keratin bonds in hair strands, then filling in the gaps with artificially derived keratin and formaldehyde. In theory, this is supposed to make the hair strand stronger and straighter.

However, the extreme heat used in these treatments can be very damaging to hair, destroying structural proteins and making the hair shaft weak and prone to breakage. Heat also causes moisture loss, drying out hair in the long run.

Formaldehyde is also known to cause skin sensitization or allergic dermatitis. Repeated contact with formaldehyde-related ingredients can cause scalp itchiness and rashes, sometimes even leading to severe hair loss.

What is keratin?

Keratin is a protein that is naturally produced in the body, and both your hair and nails are made up of keratin. In your hair, keratin is a protective protein that protects hair cells and prevents breakage and heat damage.

Keratin in hair products and treatments are usually derived from wool, feathers, or horns. Although you can purchase shampoos, conditioners, and hair masks that contain keratin, professional keratin treatments are much more effective, and the results can be dramatic even after a single treatment.

What are the benefits of keratin treatments?

Benefits of getting a professional keratin treatment may include:

  • Smooth, shiny hair. Keratin smooths the hair strands, making hair straight, shiny, more manageable, and less frizzy. The treatment can also reduce split ends by temporarily sealing the hair strand back together.
  • Long-lasting results. The results of a keratin treatment can last quite a while if the hair is cared for properly, for example by using sulfate and paraben-free shampoos and conditioners and washing hair no more than 2-3 times a week.
  • Reduced drying time. Drying time may be cut by almost half or more after a keratin treatment. 
  • Improved hair strength. Keratin treatments can help repair damaged hair, making it stronger and less prone to breakage. However, if treatments are done too often, it can eventually lead to hair damage.

What are the risks of keratin treatments?

Risks of keratin treatments include:

  • Formaldehyde. Formaldehyde can be dangerous if inhaled, irritating the eyes and nose. Formaldehyde is classified as a carcinogen by the FDA, meaning it can cause cancer in some people. Some brands hide the fact that they contain formaldehyde even if they do. Look for labels that say formalin or methylene glycol, which are potential sources of formaldehyde.
  • Cost. Keratin treatments can be expensive. There are cheaper at-home options available, but the results typically don’t last as long.
  • Maintenance. Several precautions should be taken to maintain hair health and help the results last longer. Swimming in chlorinated water or salt water (such as a pool or the ocean) can cause the results of a keratin treatment to wear off sooner. You should use shampoos and conditioners that are free of sodium chloride and sulfates because these chemicals can strip away the effects of the treatments.

How long do keratin treatments last?

A salon keratin treatment can take a couple of hours depending on the thickness and length of the hair, and results can last up to 6 months or longer depending on the products used and post-treatment hair care. 

There are also at-home keratin treatments, which can produce similar results that don’t last as long. Either way, keratin treatments should not be done more than three times a year to avoid significant hair damage.


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Medically Reviewed on 7/14/2021
Platt I, Thornberry M. What’s the Deal with Keratin Treatments? National Center for Health Research.