Kerastase vs. Olaplex

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!

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.

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.

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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.

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:

• Applying a small amount of product (or protein-rich substance such as raw egg) to a short, damp section of hair.
• Allow your hair some time to air dry.
• 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.

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Kerastase Fusio Dose 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.

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.

2024 update: It's on us for not making it clearer at the time of publishing, but Fusio Dose is indeed a salon-only product. I suppose a better comparison here would've been with Olaplex No.2 since that is also only available at the salon, whereas No.3 is available for home use. If you're looking for Kerastase's equivalent at-home product, it would possibly be the Resistance Sérum Thérapiste.

We've left the original comparison involving Fusio Dose intact below for the sake of continuity.

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.

If you're looking for an at-home treatment for your hair, it's got to be Olaplex No.3 or Kerastase Resistance Sérum Thérapiste.

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Kerastase vs Olaplex Hair Oil

Oils are integral to maintaining the health of your hair and scalp. And while your treatments and conditioners do contain nourishing oils, nothing quite beats a dedicated hair oil such as the Olaplex No.7 Bonding Oil or the Kerastase Elixir Ultime when it comes to achieving a sleek, silky, high-gloss finish.

First and foremost, it's important to note that unlike some hair oils out there, with Olaplex and Kerastase you're actually getting a blend of oils. This is key because different oils contain different vitamins, which in turn offer slightly different benefits to your hair.

The Olaplex Bonding Oil contains Corn, Sunflower Seed, Moringa Seed, and Pomegranate Seed oils. Combined, they help to dramatically increase shine, softness, and color vibrancy while minimizing frizz.

The Kerastase Elixir Ultime instead contains Corn, Argan, Camellia Kissi, and Pentaclethra Macroloba oils. The listed benefits are more or less the same as Olaplex, including damage protection, heat protection, color protection, shine, and frizz reduction.

Unlike Olaplex, though, they've really paid attention to the scent. Olaplex has a fairly default citrusy fragrance, whereas Kerastase features an exceptional blend of floral scents with Violet leaf, Freesia and Mandarin, and woody scents, with Musc extract.

As with the rest of the Olaplex line, the No 7 Bonding Oil also contains their patented bonding ingredient which visibly repairs extreme damage well beyond the capabilities of a regular oil treatment (as long as you're not sensitive or allergic to it!).

So to summarize, the choice essentially boils down to whether you're seeking luxury—with Kerastase's aromatherapeutic Elixir Ultime—or function—with the damage-reparative Olaplex No7 Bonding Oil.

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Kerastase vs Olaplex Hair Mask

In the context of hair care, a 'mask' implies to cover or conceal damage. This is as opposed to a 'treatment' which acts as an actual solution to the underlying problem. In essence, you'll want to be using both rather than one or the other.

If you're interested in the specific differences between hair masks and treatments with relation to Olaplex, check out our Olaplex 3 vs 8 comparison.

Otherwise, let's dive straight into our comparison of the Kerastase Resistance Masque Therapiste vs Olaplex No 8 Bond Intense Moisture Mask.

At the heart of both formulas is a nourishing blend of oils and plant extracts which work to deliver long-lasting moisture to your hair, and that's really what sets these products apart from alternative treatments; their complete focus on hydrating and quenching parched tresses.

"Well, isn't that just what a conditioner does?", you might be wondering. Aha, well, you'd be along the right lines by thinking that since both types of product contain the same sorts of conditioning ingredients.

However, while a conditioner provides fairly instantaneous superficial results, a hair mask penetrates the hair delivering much more significant long-term results from the inside out.

This 'penetration' is facilitated by the inclusion of Amino Acids in the case of Kerastase's Resistance Masque Therapiste, and Bis-Aminopropyl Diglycol Dimaleate for the Olaplex No8 Bond Intense Moisture Mask, which both double up as treatments for damaged hair, and help to reduce the risk of breakage.

The results speak for themselves, with Olaplex No8 boasting 2x shine, 4x moisture, and 6x smoothness according to an independent clinical study. The Kerastase Resistance Masque Therapiste hasn't had quite the same rigorous level of clinical testing, but anecdotally it seems to work equally as effectively, and with a much better scent.

The Resistance Masque Therapiste is incredibly rich, meaning that it is prone to weighing down hair if overapplied. Olaplex No8 is fairly rich, too, but it comes with a pump which allows you to better measure out the perfect amount for your hair type (1 pump for fine or short hair, 2 pumps for medium or shoulder length hair, and 3 pumps for thick or long hair).

Ultimately, we prefer the Olaplex No 8 Mask. Choosing a shampoo and conditioner for its sensorial appeal makes a lot of sense to us, but when it comes to treatments and hair masks, efficacy should always come first on the list of deciding factors.

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