Cysteine vs. Keratin: The Ultimate Hair Strengthening Face Off


Are you looking to straighten your curly locks? Hair straightening treatments like cysteine and keratin can help you to have shiny, healthy and straight hair. They can last up to six months on average. In this article, we’ll discuss more of these treatments and how they compare.

Hair Structure

Your hair consists of many layers, chemical bonds, and proteins. The actively growing cells which produce hair are present in the hair bulb. The cells arrange themselves into six layers; the first three inner layers form the cuticle, cortex, and medulla. The outer three membranes form the inner root sheath and the basement membrane.

The hair shaft made of a protein called keratin is tough and resistant to wear and tear. Eighteen amino acids make up the keratin of which the most abundant is the cysteine. It gives the hair much of its strength.

The middle layer of the hair is the cortex. It is made up of polypeptide chains that are cross-linked with each other, by three different types of side bonds. One type of side bond is the disulfide bond. These bonds are joined to the Sulphur atoms of two cysteine atoms to create cysteine. These bonds are the key factors in giving hair its strength and durability.

“Think of straight hair as a ladder and curly hair as a spiral staircase. The steps on both are the hair’s bonds. If you break those bonds, you can rebuild the spiral staircase as ladder—so curly hair becomes straight. Ammonium thioglycolate and sodium hydroxide permanently break the bonds—that’s how traditional relaxers and “Japanese straightening” treatments transform the texture of the hair.”

 “These treatments last until your hair grows out, but they can be damaging,some “keratin treatments” (and the popular Brazilian Blowout Original Solution) saturate the hair with a formaldehyde solution before it is dried and flat ironed; the formaldehyde locks the hair into that straighter position, so it stays smooth beyond your next shampoo. Your natural texture then gradually returns over two to five months,” says cosmetic chemist Randy Schueller, editor of

Cysteine Hair Strengthening Treatments

Cysteine Complex and Cysteine Hair Smoothing System are the modern forms of hair straightening treatments. These treatment uses the naturally occurring essential amino acid cysteine to straighten and strengthen your hair. They are considered safe than keratin treatments.

Cysteine is naturally absorbent and has no formaldehyde or any other harmful substances that release formaldehyde fumes under heat pressure. The cysteine treatment is semi-permanent and lasts for about three months. If you have gone through various styling and chemical treatments and have rough, dry and dull hair, you should try this hair treatment.

The cysteine hair treatment helps to strengthen your hair roots, adds shine and protects your hair from further damage. It cuts out excessive frizz and dryness and keeps your hair well in place and makes it easier to maintain. This treatment gradually fades away from the hair over time. You cannot see the line of demarcation as new hair grows out. Cysteine hair treatment is one of the safest in the market, but if you’re unsure then it is better to go in for a patch test.

Cysteine Complex Treatment

The Cysteine Complex contains botanical ingredients and pure proteins. It works in synergy with existing hair proteins to soften, restructure and release curls from hair. This formula penetrates inside the hair shaft and delivers great moisturizing and conditioning benefits which in turn improves the overall strength of your hair. The ingredients present in Cysteine Complex includes cysteine, hydrolyzed wheat protein, dendrobium orchid, shea butter and cocoa seed butter.

Facts about Cysteine Complex Treatment

The Cysteine Complex is a non-formaldehyde keratin treatment that reduces 70% curl volume on Caucasian hair and 50-60 percent curl volume on ethnic hair. You can apply this formula over any relaxers. If you use Cysteine complex over any other keratin treatment, just make sure that it has been at least two months before the previous treatment.

Experts highly recommend that you do the Cysteine Complex after the color service. This formula should be used on children 12 and over. If you’re pregnant, it is better to consult with your doctor. After the treatment, it is wise to use Sulfate free shampoos because sulfates can strip away the treatment.

Hair experts advise you not to swim in the pool for the first two days after application to let the product settle into the hair. For stunning results use KerAcai as the base product before applying any styling products to your hair. KerAcai deposits a fine layer of keratin to your hair, protecting and nourishing each strand and prolongs the life of your Cysteine Treatment.

It is best if you shampoo your hair only thrice a week. If you shampoo often, it will fade away the treatment. Do not use henna or metallic dyes before or after the treatment. It is better to highlight, re-bond or color your hair before the treatment. Regularly oiling your hair is not recommended because it will create a buildup in the hair.

Steps of Application

You must wash your hair well enough to remove any dirt or buildup. The stylist applies Amazon Series Cysteine Complex Smoothening Cream onto your hair section by section until she covers your whole hair with the cream. She doesn’t apply the cream to the roots of your hair and leaves one inch from the roots without the cream. The reason is that the cream may make the roots soft which results in hair fall. The stylist wraps your hair with a clear plastic film and makes sure that your hair does not have any folds or creases.

After half an hour the hair stylist takes your semi-wet hair section by section and dries your hair with the help of a hair straightener. Using De Fabulous Hair Repair Shampoo the stylist washes your hair and applies De Fabulous Hair Repair Conditioner, and Amazon Series Acai Oil Treatment to strengthen your hair. You should use the above products regularly for 3-4 months.

Cysteine Hair Smoothing System

The Cysteine Hair Smoothing System consists of four compartments.

  • Cysteine Smoothing Shampoo
  • Cysteine Smoothing Treatment
  • Protein Leave-In Conditioner
  • Keravis Hair Strengthening Protein Conditioner

This system straightens the hair using a sulfite/urea active straightening complex. High concentrations of cysteine are used to provide a protective shield on the surface of the hair. The amino acids extend the longevity of the treatment by helping in the restructuring of the disulfide bonds. Other noticeable proteins in the system include hydrolyzed wheat protein, hydrolyzed wheat starch, and water.

The Cysteine Hair Smoothing System was studied microscopically using an Atomic Force Microscope. Researchers investigated the 3D image of the topography of the hair fiber. They took the untreated hair as a baseline. The scientists compared the hair treated with cysteine system with hair treated with more traditional relaxers. You can see the comparison in the Figure. From the Atomic force microscopic images, the investigators found that Cysteine Hair Smoothing System closely resembles untreated hair. This formula makes your hair sleek and smooth with minimal damage and without the addition of formaldehyde.

Steps of Application

Shampoo and rinse your hair thoroughly twice using the Cysteine Smoothing Shampoo. Apply the Protein Leave-In Conditioner. Follow it up with Keravis Hair Straightening Protein Conditioner.

 Apply Cysteine Smoothing Treatment until hair is saturated. Rinse after 30 minutes using Cysteine Smoothing Shampoo. Apply the Protein Leave-In Conditioner to towel dried hair. Comb through and blow dry until 90 percent dry. Finally, flat iron to achieve smooth straight hair.

Keratin Hair Strengthening Treatments

Keratin is used in these treatments to strengthen and straighten your hair. A stylist applies the keratin straightening product to your hair. She then uses a flat iron to seal it in. The entire process takes 90 minutes or longer depending upon the length of your hair. Some of the keratin products include.

Keratin Complex Smoothing Therapy by Coppola

The innovative formula binds keratin to the hair, preventing humidity from penetrating the hair. Thus it locks out frizz. The Keratin Complex Color Therapy incorporates the keratin technology into the hair coloring process. This action makes your hair stronger and smoother as it undergoes a color transformation.

La-Brasiliana Treatment

It is a revolutionary process that contains collagen, and it transforms your hair into a healthy and shiny state. You can use this formula for all hair types. The application takes between 1.5-4 hours and creates a glossy finish that lasts up to 4 months.

Brazilian Keratin Treatment

The Brazilian treatment contains the liquid form of keratin. It does not use strong chemicals to open and close the hair cuticle to straighten it. The Brazilian keratin treatment just coats your hair and does not break the bonds of the hair shaft.

The Brazilian Blowout

Brazilian Blowout uses the professional bonding technologies that improve the condition of your hair. It creates a protective protein layer around the hair shaft to eliminate frizz and soothe the cuticle. You can leave the salon and immediately wash your hair. There is no line of demarcation with new hair growth.

Liqwd Professional Q-Keratin Smoothing Treatment

This solution uses keratin and a unique blend of protein-rich quinoa to soften, enrich and glisten strands. It is free of formaldehyde. You can retain your hair texture after the treatment, and you can style a full range of wavy, curly and straight finishes without any limitation but your hair will have a glossy, satin finish.

Tela Beauty Organics Phyto-Keratin Smoothing Treatment Blowout

It contained 85% USDA certified organic ingredients like mushroom, lemon, orange and sprouted soy all combined with plant-derived keratin to seal the cuticle in with shine and resiliency. This formula contains ceramide complex that derives lipid hydration to strands. It is formaldehyde free.

Unnique Amino

This keratin treatment is another recent launch. It strengthens strands with nanoparticle blend of amino acids. This product is free of formaldehyde. The hair becomes stronger, smoother and more manageable. It is non-irritating and does not cause allergies.

Facts About Keratin Hair Treatments

The keratin treatments are temporary, but the results last for about six weeks. If you wash your hair often, it will return to normal quickly. Keratin treatments are best for thick, curly, frizzy and coarse hair. These treatments are also suitable for damaged or chemically treated hair such as colored, relaxed, permed, highlighted and bleached. Keratin treatments are not appropriate for fine, straight or thin hair.

Sealing keratin into the cuticles can strengthen and repair your hair. If you use a hair product containing functional keratin proteins you are replacing the missing and damaged keratin from your hair. If the keratin in your product shares a sequence, form, and function of the natural keratin. It will patch up the frayed cortex and smoothen out those ruffled protein scales.

Experts say that a keratin hair treatment could reduce your blow dry time by 40-60 percent. Even if you walk in the wet or light rain, your hair won’t become frizzy. You shouldn’t wash your hair 3-4 days after getting your treatment. That’s because the solution takes the time to work. You should use sodium sulfate free shampoo to help maintain the treatment.

Use a tube of shampoo that doesn’t contain sodium chloride for long lasting results. Exposure to chlorine, sun and saltwater will reduce the lifespan of the treatment. Color two weeks before or after the treatment. However coloring hair before the treatment seals in color and helps to prevent fading.

Keratin is a restorative treatment. These treatments won’t break your hair. Hair breakage is due to the flat irons that are used to dry and seal the hair. Hair experts say that some salon workers may use a flat iron that is way too hot which scorches your hair and breaks it off. If you suffer from psoriasis or seborrheic dermatitis, check with your dermatologist before taking keratin treatments.

Formaldehyde Factor

Some keratin treatment products contain formaldehyde. Using them can raise indoor air concentrations of formaldehyde to levels that could be a potential hazard. According to American Cancer Society exposure to relatively high amounts of formaldehyde has been linked to some types of cancer in humans. If you’re concerned about this fact, then you can go in for keratin products that are free of formaldehyde to strengthen your hair.

The formaldehyde can cause health problems especially for people who regularly work with it.  The main health problems related to formaldehyde in keratin products has been about salon workers and not people who get keratin treatments.

To be on the safer side, you can ask the salon personnel if they know that the product you are going to be using contains formaldehyde-related ingredients or other ingredients you wish to avoid. Experts point out that most companies put the formaldehyde to safe limits, but some salons mix their own to incorporate more formaldehyde. The Environmental Working Group has given a list of businesses that claim little to no formaldehyde, but tests show their products contain substantial amounts. You can check the list here.


Hair strengthening treatments are used to straighten the hair and to make it shiny and healthy. Some keratin treatments do contain formaldehyde which has got a bad rap in the health circles. Experts argue that hair breakage is due to the high heat of the hot iron and formaldehyde has nothing to do with hair breakage. Formaldehyde usage affects the salon workers more than the clients. That’s why we recommend this organic product for a hair mask.

On the other hand cysteine hair treatments though do not contain formaldehyde, still uses a hot iron to seal in the product. So from my point of view keratin and Cysteine treatments are equally the same. It would be wise if you go in for hair treatments that do not use formaldehyde be it cysteine or keratin hair treatments to strengthen your hair.

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