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We're positive you've seen Kerastase and Olaplex on the shelves at your local beauty store or hair salon before. But which one should you choose?

Previously, we took a look at two luxury skincare titans: Lancome and Clarins; today, we will be comparing Kerastase vs Olaplex—two heavyweights of the hair care industry—to help you figure out which brand better suits you!

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Kerastase vs Olaplex Shampoo

A great shampoo is one that effectively cleanses your hair fibres while restoring your hair's natural pH balance, and I don't think there's a single person out there that would dispute the fact that Kerastase and Olaplex shampoos are some of the best. There's a good chance that if you've searched for this comparison, though, you're also interested in the repairing, nourishing, and strengthening qualities that Kerastase and Olaplex shampoos boast.

Best overall shampoo

When it comes to choosing a shampoo that will yield gorgeous, silky, cleansed hair, there are few like the Kerastase Resistance Bain Force Architecte Reconstructing Shampoo and the Olaplex No.4 Bond Maintenance Shampoo. But how do they differ? Is one better for you than the other? Our Kerastase Resistance vs Olaplex comparison will help you decide.

Fundamentally, each shampoo is the same but different. Riveting analysis, I know, but allow us to expand. Whilst Kerastase's Resistance shampoo contains their 'Vita-Ciment complex' comprised of ceramides to nourish and repair your hair, the Olaplex No4 shampoo contains a patented bond-repairing ingredient known as Bis-Aminopropyl Diglycol Dimaleate (quite the tongue twister!). Both essentially achieve the same glorious result by rebuilding, repairing and strengthening your hair fibres from within.

However, when we were conducting our research for this article, we fell down a deep rabbit hole that we *really* weren't expecting. For some, Olaplex products are the holy grails of holy grails, transforming hair from brittle, dry, frizzy messes into lovely, silky, beautiful manes. BUT—and this is a big but—for a small minority, it's the stuff of nightmares, leading to severely damaged hair and even hair falling out!

We've been following several discussions, including this Reddit thread and this Sephora thread, and there's no clear consensus as to what causes such drastically varying results; but, we believe we've come to a plausible conclusion: protein sensitivity. Some individuals have "protein sensitive hair", an intolerance to the strengthening effects of keratin, protein, and bonding ingredients (which are obviously present in Olaplex products) which can lead to hair loss.

To test whether or not you have protein sensitive hair, we recommend applying a small amount of product to a short, damp section of hair. Once it is dry, you will immediately be able to tell if you are sensitive to protein if the hair in that section is extremely stiff or starts breaking.

We haven't found any complaints of similar magnitude about the Kerastase Resistance Shampoo, and we absolutely love that one ourselves, so we thoroughly recommend starting there whether you're sensitive to protein or not. If you're concerned that you have an extreme intolerance, though, our recommendation is moisture, moisture, and more moisture, and for that, you should head over to our best French shampoo post.

Resistance Bain Force Architecte Shampoo by Kerastase, the best French shampoo for brittle, damaged hair.

Resistance Bain Force Architecte Shampoo by Kerastase

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Our rating: ★★★★★

Price: $$$$

A hair strengthening shampoo.

What makes it special? Utilising a Vita-Ciment Complex, this strengthening shampoo endorsed by thousands of rave reviews effectively lifts away dirt and impurities while strengthening the feel of brittle hair to help prevent breakage and split ends. Damaged hair is left feeling soft, sleek and protected.

Which hair type? For brittle, damaged hair with split ends - also works beautifully for defending normal hair types.

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No.4 Bond Maintenance Shampoo by Olaplex, one of the best overall shampoos.

No.4 Bond Maintenance Shampoo by Olaplex

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Our rating: ★★★★★

Price: $$$$

A highly moisturizing, reparative shampoo.

What makes it special? N°4 Shampoo repairs and protects hair from everyday stresses — including damaged hair, split ends, and frizz — by re-linking broken bonds. Leaves hair easier to manage, shinier and healthier with each use. N°4 is color-safe and proven to reduce breakage and strengthen all types of hair.

Which hair types? All hair types, as long as you don't have a protein sensitivity!

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Kerastase vs Olaplex Conditioner

Akin to cleansing your skin, washing your hair is a critical step, but in doing so you are stripping it of moisture, and you need to replace that moisture by using a conditioner—just like you would for your skin with a moisturizer! As far as conditioners go, there's not too many as good as those by Olaplex and Kerastase.

Best overall conditioner

The most notable and sought after comparison for the best overall conditioner is the Kerastase Resistance Ciment Anti-usure vs Olaplex No.5 Bond Maintenance Conditioner.

We recommend jumping back up to the Shampoos section for the full details, but, long story short, the miracle bond-repairing molecule that Olaplex uses triggers protein sensitivities in some people, leading to damaged hair and even hair loss in severe instances. Now, of course, this occurs in just a small minority of cases, but we would be doing a major disservice if we were not to warn our readers, and the best thing to do before buying any Olaplex product is to test yourself for protein sensitivity by:

  1. Applying a small amount of product (or protein-rich substance such as raw egg) to a short, damp section of hair.
  2. Allow your hair some time to air dry.
  3. Inspect your hair; you will immediately be able to tell if you are sensitive to protein if the hair in that section is extremely stiff or starts breaking.

Alternatively, opt for the Kerastase Resistance Ciment Anti-usure conditioner! Not only will you escape the headache of worrying about intolerances and sensitivities, but this cult-favourite product is seriously one of the best conditioners available on the market.

Resistance Ciment Anti-usure Conditioner by Kerastase, a strengthening conditioner to restore hair.

Resistance Ciment Anti-usure Conditioner by Kerastase

SHOP Check price on amazon.com

Our rating: ★★★★★

Price: $$$$

A strengthening conditioner to restore hair.

What makes it special? Reconstruct worn out hair lengths and tips. Ciment Anti-Usure, enriched with Vita Ciment Advance selectively reconstructs and reinforces the hair from inside depending on the amount of damage. At the same time recreating the outer protective layer and protecting hair from external aggressions. A blend of natural Protein and Vita-Topseal works with your hair, leaving it feeling and looking softer, healthier and more natural to touch.

Which skin types? All hair types; especially for those with damaged hair.

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No.5 Bond Maintenance Conditioner by Olaplex, a highly-moisturizing, reparative conditioner for all hair types.

No.5 Bond Maintenance Conditioner by Olaplex

SHOP Check price on amazon.com

Our rating: ★★★★★

Price: $$$$

A highly-moisturizing, reparative conditioner for all hair types.

What makes it special? Leaves hair easier to manage, shinier and healthier with each use. Protects and repairs damaged hair, split ends, and frizz by re-linking broken bonds. It is color-safe and will strengthen and leave your hair stronger than ever.

Which skin types? All hair types.

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Kerastase vs Olaplex Treatment

There's an argument to be made that all Kerastase and Olaplex products are "treatments", but sticking to the strict definition, treatments are the best way to accelerate your hair transformation thanks to their concentration of potent, nourishing ingredients. Olaplex and Kerastase each boast incredible collections of treatments that assist you in unveiling your natural, silky, luscious hair.

Best hair treatment

The Kerastase Fusio Dose and Olaplex Hair Perfector No 3 Repairing Treatment are two holy grail hair care products, but deciding between the two can be tricky.

Setting the tolerability drama aside for this comparison (skip back to the Shampoos section for more info regarding that), this is still going to be a serious apples-vs-oranges contest, and the conclusion is going to come entirely down to preference.

The first difference is that the Olaplex treatment comes in a single bottle and can be applied exactly like a conditioner or hair mask. The Kerastase Fusio-Dose, however, requires a bit of setup: first, you receive half a vial of the Fusio-Dose concentrate itself, and then you need to purchase a separate "fusio-dose booster" to pour into the vial before you're able to start using it. Once it is prepared, you then apply it to towel-dried hair with a spray.

Both treatments are incredibly popular and common at high-quality hair salons, so there's no difference there, but we might note that since the Fusio-Dose requires some customization and setup, perhaps it is more suitable as a professional treatment than an at-home solution. The Olaplex treatment, on the other hand, seems much more DIY-friendly.

On balance, then, the trade-off is customization versus ease-of-use. We just love that you can create your own treatment that caters exactly to your hair needs and concerns, though, so our pick is the Kerastase Fusio-Dose.

Fusio Dose by Kerastase, the best overall hair treatment.

Fusio Dose by Kerastase

SHOP Check price on amazon.com

Our rating: ★★★★★

Price: $$$$

A potent, customizable hair treatment consisting of a concentre and a booster.

What makes it special? Fusio-Dose treatments combine a concentre with a booster to personalise the treatment to your unique hair needs. Based on your needs, your can create a customised mix from 20 possible combinations to instantly transform your hair. Your main concern is tackled by the concentré while your secondary concern is tackled by the booster.

Which skin types? All hair types!

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Hair Perfector No 3 Repairing Treatment by Olaplex, the #1 product in prestige haircare according to NPD.

Hair Perfector No 3 Repairing Treatment by Olaplex

SHOP Check price on amazon.com

Our rating: ★★★★★

Price: $$$$

The #1 product in prestige haircare according to NPD.

What makes it special? A weekly at-home treatment, not a conditioner, that reduces breakage and visibly strengthens hair, improving its look and feel. In just one use, this product visibly and texturally repairs your hair, and it is clinically proven to yield 3x stronger hair, so that you can finally enjoy a silky, healthy mane.

Which skin types? All hair types, especially for those with visible damage.

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Work in progress

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