Editor's TipEditor's Tip

For added protection, use together with Kérastase Chroma Thermique.

Kérastase

Birchbox Breakdown

Apologies to Gehry, Libeskind, and all the other starchitects: Kerastase is giving you a run for your money—at least when it comes to jawdropping hair feats. The brand’s dual-phase serum transforms damaged hair by repairing its actual foundations—the fibers in each individual strand. Once those are fortified and healthy, the serum adds ceramides for smoothness and gloss. You’ll have a gorgeous, award-worthy coif.

How it Works

Instead of just piling shine enhancers on top of deteriorated strands, Kerastase’s two-part serum gets to the root of the problem—literally. Intra-Cylane and Pro-Keratin work together to reinforce and fill in damaged hair fibers. Then, ceramide seal the newly healthy strands and give them a sleek, uniform exterior.

How to Use

Squeeze a dime- to nickel-sized amount (depending on hair length) into palms and rub together. Run hands through damp or dry hair from mid-length to tip. Blow dry or flat iron to seal each cuticle.

More for You!
  • Free returns within 90 days of purchase
  • Extra samples and gifts in the Bonus Shop

Product Reviews & Sample Feedback

16 Reviews
4.7 out of 5 stars
5 Star
12
4 Star
3
3 Star
1
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1 Star
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Most Helpful Customer Reviews

Love it
Purchased

I heat style my hair almost every day and this product helps to control my split ends. It's great serum and addition to my hair routine.

5
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love at first pump!
Purchased

I have been wanting to try this for quite a while and I am so glad I did. I have used it a few times now and I am completely in love. I have wavy, blonde color treated hair and have been experiencing bad breakage and brittleness lately. This leaves my hair feeling so soft, shiny and my strands look healthier overall. I am hoping with continued use of this and the rest of this line it will stop the breakage I experienced. And it smells delicious!

5
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MUST HAVE for heat styling
Purchased

This is the best product I have found in 10 years of heat styling my hair. I particularly focus on ends and it leaves my hair shiny and smelling great.

5
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Lifesaver
Purchased

This serum paired with the conditioning treatment has worked wonders on my hair. I have long bleach blonde hair and get really bad breakage and split ends, but while using this I can see a difference. My hair feels so smooth and it smells amazing too! I just wish there was more in the bottle since I have to use more for my longer hair.

5
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Love it!
Purchased

Smells amazing. lightweight, non greasy...keeps hair smooth and the ends looking freshly cut. Will definitely repurchase and try more Keratase products!

5
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Magic
Purchased

This serum does wonders for damaged hair. Paired with the mask, I can really tell a difference in my hair. I highlight my hair and as a result, my hair is broken and full of split ends. I don't know whats in this product to seal those split ends, but if you have damaged hair I highly recommend! It smells amazing to boot!

5
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great product
Purchased

This product really seems to diffuse the look of split ends. I only wish that the bottle was larger. The smell is wonderful, as well.

5
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The Best Hair Product I Have Ever Used!
Purchased

I cannot rave enough about Fibre Architecte! My hairstylist introduced me to it, and I am addicted. It makes my hair feel smoother and softer than it ever has, and tames flyaways and frizz on humid days. It smells great, and it truly makes my hair feel like I just had it done at the salon. It's expensive, but totally worth the price. A little goes a long way. My highest and most enthusiastic recommendation!

5
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Love it!
Purchased

I have been using this for a few years now and keep it in constant supply so I don't find myself at the bottom of the bottle without new stock on hand. It is essential for my hair which is wavy and frizz prone in humid weather. It smooths our my locks and helps protect it from the heating elements I use on a daily basis. It's a little mnore expensive than other serums but well worth it. You don't need much (I use 2-3 pumps and I have medium to long hair) and that lasts me about 1 1/2 to 2 months. Great investment for your hair!

5
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Love the product, but tiny size
Purchased

I love the product, I feel like it gives my long hair the extra tlc it needs, leaving it soft and smooth. I am a Kerastase devotee, and am used to their styling products being the typical 4.2 ounces. I wish I had paid attention to the size when I ordered. This bottle is tiny and its expensive!!!

3
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