Editor's TipEditor's Tip

For super sleek strands, apply Kérastase’s Fiber Architecte - Prime from ends up to roots before styling with your flatiron.

Kérastase

Birchbox Breakdown

It’s a vicious cycle: You decide to grow your hair out, only to see it break and split so disastrously that you’re forced to get a trim. With this reconstructive leave-in milk, however, you can kiss breakage goodbye and say hello to newly lustrous strands. Formulated with heat-activated ingredients, this treatment strengthens and protects the hair shaft from the damage caused by heat styling, ensuring that your hair grows out long and strong.

How it Works

Hair breakage occurs when aggressive heat styling (we’re looking at you, blow dryers, flat irons, and curling irons) erodes the intercellular cement between your hair cells . Complexe Vita-Ciment strengthens fibers by reinforcing this cement, while the patented Vita-Topseal creates a strong topcoat over each individual strand, protecting it from environmental harm. The result: Hair you can comb, dry, and iron to your heart’s content—without breakage.

How to Use

Squeeze a dime-sized amount into hands and apply to towel-dried hair, starting from the ends and working your way to the roots. Gently detangle hair with a wide-toothed comb and style as usual.

Aqua/Water, Cyclopentasiloxane, Propylene Glycol, Dimethiconol, Triethanolamine, PEG/PPG-17/18 Dimethicone, Phenoxyethanol, Carbomer, Behentrimonium Chloride, Polyquaternium-4, Potato Starch Modified, Hydroxypropyl Guar, Methylparaben, Limonene, Amodimethicone, Cetyl Alcohol, Quaternium-87, Behentrimonium Methosulfate, Quaternium-33, Trideceth-6, 2-oleamido-1, 3 Octadecanediol, Geraniol, Linalool, Cetrimonium Chloride, Citral, Parfum/Fragrance

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

Product Reviews & Sample Feedback

222 Reviews
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65
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Most Helpful Customer Reviews

WOW- not what I remembered.
SampledPurchased

When I sampled this a couple years ago I remember absolutely loving it, so I have to say I'm really shocked at how awful this made my hair feel. I had just finished bleaching it, and after shampooing and doing a super deep conditioning treatment I put a little more than the recommended amount (not even double what your supposed to) in since my hair is pretty long and I just finished coloring it.. halfway through blow-drying I realized that I needed to shampoo it all out because the texture it was making my hair was just horrific. Soooo I tried again, and had the same problem with the texture. Plus this easily doubled my blow-drying time. Needless to say - I will be sadly returning this. Major let down.

1
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A must have!

I have been using this product for about 10 years and can say that it has helped my hair grow from being above my shoulders to by my waist now. I used to
blowdry and flat iron my hair every day and can say that this product helped keep my hair healthy.

5
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GREAT Product!

This product is amazing! I have been using it for years and it is great for protecting my thin/frizzy hair from heat. Very fresh and light scent!

5
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LOVE
Purchased

This brand has SAVED my hair and has made it soft, healthy and shiny. Worth every penny, I would definitely recommend this!

5
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Very good
Purchased

This product cuts down on my blow dry time. It keeps my ends moisturized for a few days (I go two-three in between washes) and it smells great. I havent been able to see long term effects yet but can't wait to keep using it.

4
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Amazing

This completely transformed my brittle, damaged hair in one use. It made my hair feel incredibly healthy and soft without weighing it down at all.

5
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Great Product

Have been using this for about a year. As others have said - it smells FABULOUS - very clean and light, not floral or "chemically." I use it in combination with Kerastas shampoos and masques and after about six months of use of this combo, my hair is in SIGNIFICANTLY better condition. I have fine straight hair and use a blow dryer and curling iron daily, so I am very prone to heat damage. Unlike others, I can't say that each time I style my hair looks or feels different than if I hadn't used it, but it absolutely has been part of improving my hair and its appearance over time by improving its overall condition and health.

5
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Amazing product
Purchased

This product has helped keep my color-treated hair feel like silk, even through daily blow-drys. Amazing, and well worthy the investment.

5
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Never fails
Purchased

I've used this particular product for years and it does a great job of protecting my hair from heat products. It's not too heavy for my fine hair. Smells terrific. Combs through damp hair easily.

5
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Life Saver!
Purchased

I have long (lower back) hair, but its extremely curly- which i hate to wear natural. This product saves my hair from the constant heat damage from the blow dryer/flat iron. Just ordered my 2nd bottle. LOVE IT!

5
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