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K18 Leave-In Molecular Hair Mask, Repairs Dry or Damaged Hair, Reverse Hair Damage from Bleach, Color, Chemical Services & Heat

4.3 out of 5 stars 22,917 ratings

K18
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$75.00 $44.12 per fluid ounce
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Purchase options and add-ons

Brand K18
Item Form Cream
Material Feature Natural
Hair Type Damaged
Product Benefits Our K18PEPTIDE™ repairs hair at a molecular level across multiple types of bonds, restoring hair health for all See more

Additional Details

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Description

This leave-in treatment mask works on the molecular level to reverse hair damage in just 4 minutes. It tackles daily damage with immediate and lasting results to restore strength, softness, smoothness and bounce to hair

Benefits

Our K18PEPTIDE™ repairs hair at a molecular level across multiple types of bonds, restoring hair health for all

Suggested use

Shampoo, do not condition. Towel-dry thoroughly. Apply 1-3 pumps of K18 mask & massage through hair. Let treatment sit in the hair for 4 minutes. Do not rinse

Complete the regimen
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$75.00 ($44.12/fluid ounce)
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Product Description

mask image
The video showcases the product in use.The video guides you through product setup.The video compares multiple products.The video shows the product being unpacked.

K18 Molecular Repair Hair Mask

Merchant Video
mask reverse damage
k18 hair routine
  • The K18 Mask works as a treatment to reverse damage in 4 minutes. It’s powered by our biomimetic K18PEPTIDE to seamlessly fit in and reconnect broken polypeptide chains at the molecular level.

  • K18PEPTIDE is a biotech-developed peptide that mimics hair’s structure to reverse damage by reconnecting polypeptide chains and disulfide bonds broken during damage from bleach + color, chemical services, and heat.

  • Conditioner leaves a film that blocks our peptide from penetrating effectively. Once the 4-minute wait time is up, feel free to use a conditioner, a leave-in, or any type of product.

  • We like to keep our formulas minimal, only using the exact amount of ingredients needed to get the peptide where it needs to go. Here the alcohol serves as an agent to optimize the hair environment for the K18 Mask to work on a deeper level.

  • Most see results after 2-3 uses. The more damaged the hair, the more dramatic the results so it may vary depending on your hair type and level of damage.

Shop the K18 Collection

Molecular Repair Mask

Molecular Repair Oil

Damage Shield Shampoo

Detox Shampoo

Damage Shield Conditioner

AirWash

Customer Reviews
4.3 out of 5 stars 22,917
4.3 out of 5 stars 1,361
4.4 out of 5 stars 580
4.6 out of 5 stars 1,464
4.5 out of 5 stars 622
4.2 out of 5 stars 255
Price
$75.00 $65.00 $36.00 $38.00 $36.00 $48.00
Molecular Repair
Maintenance Routine
Treatment Routine
Used By Professionals
At Home Use

Product details

  • Product Dimensions ‏ : ‎ 1.9 x 1.9 x 4 inches; 3.2 ounces
  • Item model number ‏ : ‎ K18-31005
  • UPC ‏ : ‎ 858511001029 858511001128 729162271362 729162270877 755801147958 726929222179 729162271317 729162271249 729162271096
  • Manufacturer ‏ : ‎ K18
  • ASIN ‏ : ‎ B0961ZS96M
  • Country of Origin ‏ : ‎ USA
  • Customer Reviews:
    4.3 out of 5 stars 22,917 ratings

Customer reviews

4.3 out of 5 stars
22,917 global ratings

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Customers say

Customers find the hair mask highly effective and appreciate its softening effects, with one describing it as making hair like silk. The product helps revive over-processed bleached hair and makes it look healthy and shiny. While some customers report that their hair feels stronger after using it, others experience plenty of breakage. The product receives mixed feedback about its size, with many finding the bottle too small for the price, and opinions vary on whether it helps with dryness.

AI-generated from the text of customer reviews

952 customers mention "Effectiveness"791 positive161 negative

Customers find the hair mask works well, with one noting that the results improve with continued use.

"...My hair feels soft, is nice and shiny and there is no frizz. It is light weight and smells good...." Read more

"...First of all, it’s simple to use. But more importantly, the results are fantastic! It has no strong smell and it doesn’t weigh my hair down...." Read more

"...It’s lightweight but highly effective, and I love how it repairs my hair without weighing it down...." Read more

"...It’s worth a try if your hair is damaged from bleach 👌🏼..." Read more

783 customers mention "Hair softness"721 positive62 negative

Customers report that the hair mask makes their hair softer and more manageable, with one customer noting it feels like silk, while others describe it as frizz-free and sleeker overall.

"...I used it this morning after my shower and it really does work. My hair feels soft, is nice and shiny and there is no frizz...." Read more

"...It has no strong smell and it doesn’t weigh my hair down. My hair is smooth and shiny and even has more volume. It looks so healthy and “younger”...." Read more

"...I’ve used it multiple times before, and each time my hair feels softer, stronger, and healthier...." Read more

"...Smooths on my damaged hair very easy, feels and smells good. You only 3 pumps, use 4-6 washings then take a break. Working so far !..." Read more

275 customers mention "Shine"241 positive34 negative

Customers report that the hair mask makes their strands look shinier and healthier, with one customer noting that their hair has maintained this appearance for six months.

"...My hair feels soft, is nice and shiny and there is no frizz. It is light weight and smells good...." Read more

"...My hair is smooth and shiny and even has more volume. It looks so healthy and “younger”...." Read more

"...The K18 has helped with the damage, added shine back to my hair, and lessened the amount of hair that falls out...." Read more

"...feel thick or greasy but it just made my hair feel and look soft, shiny and healthy...." Read more

399 customers mention "Hair repair"253 positive146 negative

Customers have mixed experiences with the hair mask's repair capabilities, with some reporting that it helped revive their hair and saved it, while others found it did not improve their hair quality or was not healthy for their strands.

"...lightweight but highly effective, and I love how it repairs my hair without weighing it down...." Read more

"...IT DOES NOT REPAIR DAMAGE" Read more

"...The K18 has helped with the damage, added shine back to my hair, and lessened the amount of hair that falls out...." Read more

"I cannot rave enough about the K18 Hair Mask—it has truly saved my hair! I used to pull my hair every day, causing so much damage and breakage...." Read more

259 customers mention "Strength"168 positive91 negative

Customers have mixed experiences with the hair mask's strength, with some reporting that their hair becomes stronger and breakage stops, while others note that their hair becomes brittle over time.

"...used it multiple times before, and each time my hair feels softer, stronger, and healthier...." Read more

"...This product hardens and kinda expands when you rub it in your hands so I highly recommend rubbing it in your hands before rubbing through your..." Read more

"...It shortens my shower time, extends the life of my conditioner, makes brushing my hair effortless, and leaves my hair looking healthy once..." Read more

"...The breakage has dramatically reduced, and the texture has improved—my hair feels stronger and more manageable...." Read more

242 customers mention "Dryness"98 positive144 negative

Customers have mixed experiences with the hair mask's effect on dryness, with some reporting less dryness while others mention their hair ends up feeling dry.

"...Second time trying it, it just left my hair dry...." Read more

"...I applied more than suggested and still, my hair soaked it up...." Read more

"...It was just dry and frizzy...." Read more

"...It doesn't make your hair dried or fried. It does exactly what it says...." Read more

762 customers mention "Value for money"151 positive611 negative

Customers find the hair mask expensive, with several noting that the bottle size doesn't justify the price.

"...It is a little pricey to me but it seems to be worth it...." Read more

"...It looks so healthy and “younger”. It’s expensive, but I think I’m going to have to make room for it in my beauty budget!..." Read more

"Pricey .... but I believe it's doing its magic. Smooths on my damaged hair very easy, feels and smells good...." Read more

"Expensive but so worth it if you have chemically treated or bleached hair...." Read more

242 customers mention "Bottle size"62 positive180 negative

Customers find the bottle size of the hair mask too small, particularly noting that it doesn't provide enough product for shoulder-length hair.

"Yes, the bottle is TINY. However, I noticed a difference after one use!..." Read more

"...The bottle is quite small for me to pay that amount it’ll have to do wonders not just make my hair soft." Read more

"...It shortens my shower time, extends the life of my conditioner, makes brushing my hair effortless, and leaves my hair looking healthy once..." Read more

"...The brand's bundles are a nice idea but again, the high cost and dismal size of the product received do not match up...." Read more

Pricey!!! But seems to work after only one use!
4 out of 5 stars
Pricey!!! But seems to work after only one use!
Not using conditioner when my hair is so damaged seemed crazy! I usually put quite a bit of conditioner on my hair to be able to comb through it. I bought the bigger size and it’s REALLY small for the price. I saved a little money by choosing “subscribe and save”... I used the shampoo, 3 pumps of this & 4 drops of the oil. Surprisingly with only 3 pumps I was able to get my brush through easily! It didn’t look like enough. Nor did my hair instantly feel smooth when applying. So definitely wait the 4 minutes before combing it through. My hair is fairly thick, about 1/2 way down my back and I recently bleached it from my natural brown to blond. I bought the shampoo/ conditioner & oil. My hair is so damaged after bleaching it. :( I’ve tried several recommendations to get it healthy again. Mondo & others haven’t worked. So I was up to try this! It felt softer after using it for the first time! There isn’t much scent and my hair isn’t greasy. I’ll use it 4-6 more times and hopefully my hair will look much healthier as promised. I live where it’s fairly humid. If this works well for that, it'll be worth it!
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Top reviews from the United States

  • Reviewed in the United States on April 5, 2025
    Size: 0.51 Fl Oz (Pack of 1)Verified Purchase
    Lives up to the hype. I've heard a lot about K18 but was skeptical. It's getting warmer and more humid where I live and my hair gets frizzy in high humidity so I thought I'd give this a try. I used it this morning after my shower and it really does work. My hair feels soft, is nice and shiny and there is no frizz. It is light weight and smells good. I only used 4 pumps on my hair that is just above shoulder length. It is a little pricey to me but it seems to be worth it. I will likely buy this again - but maybe I'll just use it in the summer when my hair gets frizzy.
    15 people found this helpful
    Report
  • Reviewed in the United States on April 14, 2025
    Size: 0.51 Fl Oz (Pack of 1)Verified Purchase
    I was honestly kind of expecting this to be one of those TikTok-viral, snake oil products. But my hair has become less shiny and healthy as I’ve aged (I’m 57) and it has recently started to break off. I did a google search and found this product and decided to give it a try. I’m so pleasantly surprised! First of all, it’s simple to use. But more importantly, the results are fantastic! It has no strong smell and it doesn’t weigh my hair down. My hair is smooth and shiny and even has more volume. It looks so healthy and “younger”. It’s expensive, but I think I’m going to have to make room for it in my beauty budget! You don’t use regular conditioner when you use this product, so that will help offset the cost (because my regular conditioner is expensive too).
    20 people found this helpful
    Report
  • Reviewed in the United States on April 4, 2025
    The K18 Molecular Repair Hair Mask is by far my favorite K18 product. I’ve used it multiple times before, and each time my hair feels softer, stronger, and healthier. It’s lightweight but highly effective, and I love how it repairs my hair without weighing it down. The Detox Shampoo and Molecular Repair Hair Mask are the only ones that really worked for my hair.

    Unfortunately, the regular shampoo, conditioner, and oil didn’t work for me—they left my hair dull and dry. But these two are worth the hype and have earned a spot in my routine.
    11 people found this helpful
    Report
  • Reviewed in the United States on May 5, 2025
    Not using conditioner when my hair is so damaged seemed crazy! I usually put quite a bit of conditioner on my hair to be able to comb through it.

    I bought the bigger size and it’s REALLY small for the price. I saved a little money by choosing “subscribe and save”... I used the shampoo, 3 pumps of this & 4 drops of the oil. Surprisingly with only 3 pumps I was able to get my brush through easily! It didn’t look like enough. Nor did my hair instantly feel smooth when applying. So definitely wait the 4 minutes before combing it through.

    My hair is fairly thick, about 1/2 way down my back and I recently bleached it from my natural brown to blond. I bought the shampoo/ conditioner & oil. My hair is so damaged after bleaching it. :( I’ve tried several recommendations to get it healthy again. Mondo & others haven’t worked. So I was up to try this!

    It felt softer after using it for the first time! There isn’t much scent and my hair isn’t greasy. I’ll use it 4-6 more times and hopefully my hair will look much healthier as promised. I live where it’s fairly humid. If this works well for that, it'll be worth it!
    Customer image
    4.0 out of 5 stars
    Pricey!!! But seems to work after only one use!

    Reviewed in the United States on May 5, 2025
    Not using conditioner when my hair is so damaged seemed crazy! I usually put quite a bit of conditioner on my hair to be able to comb through it.

    I bought the bigger size and it’s REALLY small for the price. I saved a little money by choosing “subscribe and save”... I used the shampoo, 3 pumps of this & 4 drops of the oil. Surprisingly with only 3 pumps I was able to get my brush through easily! It didn’t look like enough. Nor did my hair instantly feel smooth when applying. So definitely wait the 4 minutes before combing it through.

    My hair is fairly thick, about 1/2 way down my back and I recently bleached it from my natural brown to blond. I bought the shampoo/ conditioner & oil. My hair is so damaged after bleaching it. :( I’ve tried several recommendations to get it healthy again. Mondo & others haven’t worked. So I was up to try this!

    It felt softer after using it for the first time! There isn’t much scent and my hair isn’t greasy. I’ll use it 4-6 more times and hopefully my hair will look much healthier as promised. I live where it’s fairly humid. If this works well for that, it'll be worth it!
    Images in this review
    Customer imageCustomer imageCustomer image
  • Reviewed in the United States on March 22, 2025
    Size: 0.51 Fl Oz (Pack of 1)Verified Purchase
    Yes, the bottle is TINY. However, I noticed a difference after one use!
    It says to skip conditioner, use the K18, wait 5 minutes, then add your hair products and style as usual. But with as thick as my hair is, I don’t skip conditioner.
    I’ve been blonde for years and went back to my black roots. Used black box dye to cover up the random grays that would come through and got tired of that so started going back lighter. I got balayage and it ruined my hair. Tbh I don’t think the hair stylist knew what she was doing but that’s besides the point. My hair was falling out in huge clumps through out the day and when washing and brushing. The K18 has helped with the damage, added shine back to my hair, and lessened the amount of hair that falls out.
    There’s not much of a scent to the product. It’s light weight. I use more than 4 pumps too. I use about 8-10 pumps. My hair is THICK and half way down my back length wise. I use this once a week and so far it’s been almost a month and I still have plenty left in the bottle. It’s worth a try if your hair is damaged from bleach 👌🏼
    18 people found this helpful
    Report
  • Reviewed in the United States on April 13, 2025
    Size: 0.51 Fl Oz (Pack of 1)Verified Purchase
    Expensive but so worth it if you have chemically treated or bleached hair. I was worried it would feel thick or greasy but it just made my hair feel and look soft, shiny and healthy. Super easy to apply and light weight while being deeply nourishing. I applied more than suggested and still, my hair soaked it up. My hair stylist actually commented on how healthy my hair felt recently and I attribute it entirely to k18
    7 people found this helpful
    Report
  • Reviewed in the United States on October 7, 2024
    I fell in love with the K18 Leave-In Molecular Hair Mask about a year ago after my hairdresser introduced me to it. While it’s on the pricier side, its effectiveness and quality make it worth every penny. When I’m unable to splurge, I turn to my regular leave-in spray, Perfect 10 Lite.

    As someone with thin, color-treated hair that tangles easily and suffers from damage, this product has been a game changer. It shortens my shower time, extends the life of my conditioner, makes brushing my hair effortless, and leaves my hair looking healthy once styled.

    I recently purchased the larger size, fully aware of the cost. However, when I opened my package, I briefly thought I either ordered the smaller size by mistake or received the wrong item. I realized it was indeed the larger size I ordered and I debated returning it.

    The true test came when I woke up with a legit rat's nest. I was so thankful I had this product on hand, as it made detangling much easier than previous times when I had nothing to help with the mess.

    One note: I read a review suggesting that you should rub the product between your palms to activate it before applying it to your hair. That makes sense, and I’ll definitely give it a try. However, I find it quite unethical that the company leaves this step out of the instructions on the box and bottle. It feels like they might not want you to use it correctly so that you’ll need to buy more sooner—quite disappointing!
    152 people found this helpful
    Report

Top reviews from other countries

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  • Amazon Customer
    5.0 out of 5 stars K18
    Reviewed in the United Kingdom on April 21, 2025
    Really good product. Use sparingly but does the job.
  • Maram Almilhim
    5.0 out of 5 stars Love it
    Reviewed in Saudi Arabia on November 3, 2024
    Size: 0.51 Fl Oz (Pack of 1)Verified Purchase
    👍🏻
  • Stella
    4.0 out of 5 stars Good but tiny
    Reviewed in Sweden on February 15, 2025
    Size: 0.51 Fl Oz (Pack of 1)Verified Purchase
    Customer image
    Stella
    4.0 out of 5 stars
    Good but tiny

    Reviewed in Sweden on February 15, 2025

    Images in this review
    Customer image
  • Gabi
    5.0 out of 5 stars Buen funcionamiento
    Reviewed in Spain on August 29, 2024
    Textura ligera, un pequeño pump da para media melena. Ideal para mantener pelo seco, estropeado o dañado. Leer bien el funcionamiento y el proceso. El olor podría mejorar, huele a químico. Percepción personal.
    Report
  • KP
    5.0 out of 5 stars Great product
    Reviewed in Canada on February 23, 2025
    My hair was very damaged and whole this product is fairly pricey I felt that it really helped repair my damaged hair

Product Summary: K18 Leave-In Molecular Hair Mask, Repairs Dry or Damaged Hair, Reverse Hair Damage from Bleach, Color, Chemical Services & Heat

From K18

4.3 out of 5 stars, 22,917 ratings

Customer reviews

2K+ bought in past week

Price

One-time purchase: $75.00 ( $44.12 / fluid ounce)

Subscribe & Save price (No fees, Cancel anytime): $71.25 ( $41.91 / Fl Oz) 5% Savings

List Price: $75.00

Additional savings available through Subscribe & Save (No fees, Cancel anytime)

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About this Item

  • An At-home Leave-In Treatment infused with the patented K18Peptide that renews hair to its most youthful, healthy state. Benefits: Works to repair even the most extreme damage caused by bleach and color, chemical services, and heat.
  • Creates Like Hair Like New: Traveling into the inner-most layers of hair to reach the core polypeptide chains our revolutionary K18Peptide is just the right size and makeup to reconnect broken chains responsible for hair strength and elasticity.
  • Renews All Hair Types: K18 doesn’t just hide damage or patch it up leaving hair brittle, it transforms even the most extreme damage into hair that looks and feels like new. K18 works on all hair types, all generations, all types of expression.
  • Lasting Results That Won't Wash Away: The K18Peptide mimics the natural building blocks of hair and therefore is recognized as natural—so it’s able to integrate itself with the keratin chains to rebuild and restore hair immediately and over time.
  • Back By Biotech: K18 is the world’s first patented biotech treatment that renews chemically damaged hair from the inside out in just 4 minutes, strength, softness, smoothness, and bounce are restored for hair that looks and feels like new.

Product Description

K18 Leave-In Molecular Repair Hair Mask, 4-Minute Speed Treatment, Renews Hair Damage From Color, Chemical Services Heat

Options Available

Size

  • 0.51 Fl Oz (Pack of 1)
  • 50 ml
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Important Information

Safety Information

For external use only. Avoid contact with eyes. Keep away from naked flame or direct heat sources.

Directions

After Shampooing,Towel Dry Thoroughly.Begin With 1 Pump,Add More As Needed.Let Sit For 4 Minutes To Activate.Do Not Rinse,Style As Usual

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