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What Are the Different Keratin Side Effects?

By Wanda Marie Thibodeaux
Updated May 22, 2024
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Keratin is a protein found naturally in the human body that makes up physical structures such as the hair and nails. When these basic structures become weakened and keratin is lost, it is possible to add keratin through cosmetic processes to fill in gaps in the original keratin fibers, providing better strength. Most commonly, people use keratin as a hair straightening treatment. The possible keratin side effects include hair loss, allergic reactions, itching, rashes, irritation of the eyes, lungs, throat, mouth and nose, hair dryness, and cancer. These side effects are not from the keratin itself, but from the processing tools and additives included with the keratin products that help them work.

Some people who use keratin products find that, after a treatment, hair is extremely dry and brittle. In some cases, this leads to breakage and thinning of the hair. This happens because cosmetologists use heat-based styling tools such as flat irons to coax the hair straight. The heat saps the moisture from the strands and causes a loss of elasticity. The problem worsens as an individual continues to style the hair with heat-based tools, unless she is vigilant about using conditioning and moisturizing treatments.

Almost all of the other keratin side effects are due to the formaldehyde the products include. Formaldehyde helps hold the keratin molecules together, which is largely what makes the product effective. This chemical is a known carcinogen. Problems such as irritation of the throat and lungs come from inhaling the formaldehyde during processing. Experts recommend that keratin products have no more than 0.02 to 0.2 percent formaldehyde for this reason, but this is problematic because the treatment is not as effective with anything less than 2 percent, with many manufacturers making products with percentages as high as 10 percent. 


Concerns about keratin side effects have led professional health agencies to crack down on companies that have unsafe levels of formaldehyde in their keratin products. In response, some manufacturers replace formaldehyde with other chemicals. These manufacturers can and do market these products as formaldehyde-free, but the products are not necessarily safer. Other manufacturers remove harmful ingredients, replacing them with plant-based ingredients to seal the keratin, but these wash out easily and sometimes lose their effectiveness after just one wash.

Despite concerns about keratin side effects, some individuals continue to use keratin products because of the convenience and beauty they believe is found with straighter hair. Many women, for example, can spend well over an hour trying to wash, blow-dry and iron kinks, curls and waves out of hair. With a keratin treatment, a person can sometimes finish styling in just a few minutes. Cosmetologists have greater risk for keratin side effects because they work with keratin products on a much more regular basis compared to their clients.

What Is Keratin Treatment?

A keratin treatment is a chemical process that leaves your hair straight and glossy for up to six months. It is also called a Brazillian Blowout. It is usually done in a salon and can take several hours to finish. A hairstylist brushes the treatment onto your hair, lets it sit for 30 minutes, and then washes it out.

Depending on the preferences of your hairdresser, they blowdry your hair first, and then the treatment is applied. Afterward, they will flat iron the hair to seal in the treatment. The process can even keep in color after color treatments. Keratin treatments have positive benefits for hair like:

  • Smooth, Shiny Hair: Your hair will be silkier, and split ends will be less noticeable. Frizz will have a reduction, and your hair will be glossy.
  • More Manageable Hair: If your hair is thick or tends to frizz, keratin can make your hair more manageable and quick to style. Drying time may be cut down significantly as well. 
  • Hair Growth: Keratin is a well-known ingredient that can strengthen hair. Since your hair won't break easily, you may see length retention and growth. 
  • Long-Lasting Results: When you get a keratin treatment, you only need to wash your hair two to three times a week. If you stick to this, it should last around six months. 

There is not a lot of damage when getting the treatment done, as keratin is a nourishing and strengthening ingredient. However, damage can occur when it is time to flat iron your hair. This treatment is best for those with thick, coarse hair that want a smoother texture. Those with super-fine and thin hair should not get this treatment done. It is due to the heat from the flat iron that can cause damage and lead to hair loss.

You should also be aware that many salon keratin treatments contain formaldehyde, which can be harmful. If you are sensitive to this ingredient, you may try a different straightening process.

You may hear about Japanese straightening as well. These two processes may seem comparable, but they are not. Japanese straightening permanently alters your hair texture, while a keratin treatment eventually fades away.

You need to wait two to four days before washing your hair to get the best results from the process. If you find that too long to wait before washing your hair, a keratin treatment may not be correct for you.

How Long Does Keratin Treatment Last?

As stated, if you take care of your hair appropriately, a keratin treatment can last for three to six months. Use sulfate-free shampoos to make it last longer. You can get one two to three times a year without damaging your hair.

There are several factors to think about when figuring out how long the treatment will last:

  • How often you wash your hair: As mentioned, don't wash your hair more than two to three times a week. If you do this, the process should last about six months.
  • What you sleep on: Sleep on silk pillowcases to get the best results. Cotton pillowcases cause friction, breakage, and frizziness. Silk cases are necessary to extend your treatment. 
  • What products you use: Use appropriate hair products to ensure your treatment lasts longer. Sulfate-free shampoos are usually the best kind. 

You should also know what activities you enjoy, such as swimming. Saltwater can damage your hair and shorten the life of your keratin treatment. Try wearing swim caps or swimming in other types of water to preserve your keratin process and get the most out of it.

What Does Keratin Do for the Hair?

Keratin helps strengthen your hair and make it more manageable. It imparts gloss and shine and can cut drying time in half. If you find that your hair is particularly unruly at times, keratin can help. It smooths down the cells that form your hair strands and makes your hair look fuller and healthier.

However, this depends on the texture, thickness, and what kind of keratin treatment you use. In general, keratin is beneficial and helps with hair growth. You will also have improved elasticity since keratin fills gaps in your hair and protects it. It can make styling your hair with heat tools less damaging and protects against brittleness and breakage.

Keratin also protects against UV damage, which many overlook when dealing with hair care. When spending time outdoors, it is essential to think about protecting your hair from the sun's rays. Damage from the sun can lead to weak hair and breakage.

What Should You Expect When Getting a Keratin Treatment?

Expect to spend up to four hours at the salon when you go to your keratin treatment appointment. First, your stylist will shampoo your hair twice. He or she will use a clarifying shampoo both times to ensure that your hair is very clean and doesn't have any buildup of styling product in it. Next, your stylist will comb the keratin solution through your wet hair. Don't be worried if you start to feel a bit itchy, as it's a normal side effect of the treatment. Your hair's length, texture, and thickness will determine exactly which keratin product the stylist will use and in what amount. Finally, your stylist will use a blow dryer and then use a flat iron to seal in the treatment and create smooth hair.

FAQs on Keratin

Is Keratin Good for Hair?

Keratin treatments have a wide variety of benefits for the hair. First, it creates smoother and shinier hair. Keratin smooths out the strands of hair to reduce frizz, reduce split ends, and give hair a glossier, shinier look. The treatment creates hair that is much easier to manage as well. This is especially true if you are someone who often deals with frizzy hair. If you use blow dryers or other heat styling tools, you may notice that your hair dries and styles faster, which can even save you time in the morning. Finally, since keratin is fortifying your hair, you are likely to find that it grows faster and stronger, creating the healthy tresses you want.

Can You Use Keratin Treatments if You Have Curly or Color-Treated Hair?

Yes, you can use keratin treatment if you have naturally curly hair or if your hair is color-treated. In fact, if you have curly hair, the keratin treatment will almost completely smooth out frizz and keep your hair looking shinier. Keratin is also helpful over freshly colored hair because it helps to keep the color looking new and vibrant by sealing it in and making it last longer.

What Are the Disadvantages of Getting a Keratin Treatment?

While keratin treatment provides a lot of benefits for your hair, it does have some drawbacks as well. Perhaps the biggest drawback is the fact that the treatment often uses formaldehyde, which can be dangerous if inhaled. If you decide to get keratin treatment for your hair, it's a good idea to find a salon that doesn't use formaldehyde-based products.

Depending on your lifestyle, a keratin treatment can also be hard to maintain. If you swim in pools or the ocean often, then your keratin treatment won't last as long because the chlorine and salt will penetrate the hair faster. You may also need to buy new shampoo if yours doesn't meet the keratin treatment requirements. Finally, if you are pregnant, it is not recommended that you use a keratin treatment on your hair.

How Much Is a Keratin Treatment?

Because keratin treatment is a lengthy process that has long-lasting results, expect your time at the salon to get pretty pricey. Although costs vary between salons and cities, you usually won't see keratin treatment for less than $250. In larger cities or at high-end salons, you can expect to pay closer to $500 for the treatment. Even so, if you switch from regular blowouts to keratin treatments, you'll likely save money in the long run.

Does Everybody Get the Same Results With a Keratin Treatment?

It's important to understand that results vary when someone gets a keratin treatment, and you'll not know exactly what you'll get until you have the treatment done for the first time. While most people end up with straight, glossy hair, some people have slightly different results. This is especially true if you have very curly hair. If your hair has very tight curls, a keratin treatment may still leave you with slight waves that you'll need to flat iron if you want a totally straight hairstyle.

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Discussion Comments

By anon1005787 — On Nov 20, 2021

Well, I have eczema so I'm used to my skin weeping, but I have always been able to use cocoa butter lotion or any kind of moisturizer on my skin and it would help. But since I moved into the place I live in now (two years ago) my skin feels like sandpaper and nothing helps. Also, my hair has not grown in two years since we have moved in here. I got sick back at the end of May with ammonia pneumonia and shortly after starting to feel better and recover, I noticed my hair was thinning and now I can see my scalp if I move my hair a certain way. I have always had thick hair and it never took long to grow back if I cut my hair. My house is very dry and we have a lot of nitrates in our water/. Could this be causing my skin problem and my hair falling out?

By Heavanet — On Jan 27, 2014

When possible, it is best to avoid any products that have formaldehyde in its contents. If you want to reduce the risk of side effects to keratin, look for the formaldehyde-free kind, possibly available at a health foods store.

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