K18 reviews and discussion

4.6

88% of reviewers would recommend to a friend

Reviews mention

  • Lightweight oil, silky finish
  • Fast-absorbing mask, non-greasy feel
  • Noticeable repair on bleached hair
  • Frizz-taming performance, lasting shine
  • Harsh shampoos, scalp dryness
  • Airwash residue, limited longevity
  • Mask heaviness, clumping risk
  • Oil scent, chlorine-like notes

K18 earns strong reviews for visibly repairing damage and boosting shine and softness—especially on bleached, heat-styled, or frizz-prone hair—yet feedback is mixed on the leave-in mask’s results for healthy hair. Reviewers praise the lightweight oil, innovative AirWash dry shampoo, and fast, non-greasy finish, while noting drawbacks like potential heaviness or clumping if overused, harsh shampoos for some, residue and limited longevity from AirWash, and occasional scent and buildup concerns.

AI summary based on Thingtesting reviews

39 reviews and posts

  • If you lighten your hair this system will do wonders for you - You’re going to see less shedding, sleeker and stronger hair after incorporating this into your routine. I absolutely love the K18 system! I do a lot of black to blonde transformations - I’m a blonding specialist so using a bonding treatment during my services are key to maintaining the health of my clients hair. I switched my clients over from Olaplex to K18. Yes K18 is more costly but you are using less product. I used the pro mist, chelating spray, detox shampoo and leave in mask. I recommend my clients use the leave in mask for at home use. It is recommended to use the mask after the first 4-5 washed after getting your hair lightened. Hair page on Insta @nessastyles__

  • I first test it 2 years ago to see if the hype was real. The hype really is real (!!!) The leave-in mask ; it was like I had new hair. I had over the years alot of colors, of heat and bleach for 4 years now. For the black friday I bought the kit, oil, mask and the peptide ; I live for it. But for the oil, you should not use more than 2-3 drops, because it becomes greasy quickly

  • Revolutionized my hair. Idk if its evolved but the product has helped

  • Recommended by my hairdresser and I've never gone back. I use the shampoo, conditioner, and the mask and it's done wonders to my hair. As a girl who bleaches her hair, K18 ensures it stays healthy.

  • Was recommended by my hair stylist, I tried the bond treatment and love it!

  • I've heard nothing but great reviews for K18 so I was just really disappointed with the leave in treatment. My hair felt only marginally better than it does when I put absolutely no leave-in on. Sometimes my hair even felt oily and clumpy when dry, as if I didn't wash out my conditioner fully.

  • The leave in conditioner product is pretty insane — I've only ever had samples and a travel size bottle that I purchased but I really enjoy this product.

  • I’ve used K18 for 2 years now and love that it makes my hair healthy in a light way. There’s no built-up and a little product goes a long way which also kind of justifies the high price. Both shampoos are too harsh for me and I can only use them occasionally instead of regularly. I also love the oil bc it’s lightweight and results in shiny hair.

  • My stylist is an ambassador for K18 and swears that it's unbeatable in repairing damaged hair (from bleaching, which I was doing for 2-3 years). It's pricey but you don't have to use it that often. The leave-in mask is easy to use once you figure out the right amount (too much and your hair will clump together). My hair is still pretty dry though after a while of using it "as needed" and I've needed to still use other hydrating/repairing products. Honestly I'm not really sure if it did anything??

  • The hype is REAL. I bought a starter kit during the Sephora Sale and can say I will for sure be repurchasing the Peptide Prep Shampoo and Leave in Mask. The hair oil I think is a little too heavy for me, but I will try it again later. This made my hair so smooth and silky and lacked all the texture and dryness it usually does from heat and styling.

  • Being a hairstylist and in the beauty industry for years, I am always a sceptic on brand claims. The first time I used K18 mask, I was shocked and wondered what magic was in this bottle. This client came to me for the first time, and she blow dried and flat ironed her hair every single day. Her hair had so much breakage on the ends, but I tried the professional mist + mask. After her color it was the bounciest and shiniest I've ever seen. Ever since then (January 2021) I have been a firm K18 believer. I am part of the stylist collective, but my first year using them, I had no affiliation. Everyone from bleached hair, permed, relaxed or even virgin hair can benefit from the K18 mask. It helps repair damage from heat, chemicals, mechanical styling, and pollution. The new shampoos are outstanding. The detox cleans the scalp so well, I can go an extra day without shampooing. The pH maintenance gives such a lovely lather and feel great too. I am so grateful to have K18 behind the chair. I have been able to take my clients' hair beyond what would normally be possible with no damage.

    Influencer for K18
  • This works for my hair. It eliminates frizz and makes my hair shiny and wavy. I love how fast it is - you don’t have to wait 10 min and then rinse out like so many hair masks.

  • This stuff is insane. I've never felt my hair be so healed and nourished without any kind of greasy residue, which tells me it's because my heart is actually healthy and not just coated with product residue. It's pricey but a little goes a long way.

  • Within the last month I started using the K18 shampoo and conditioner in rotation with my Olaplex. I have been using the molecular repair once a week for a few months, and I really like it. I have very fine hair and it isn't heavy at all.

  • It did make a big difference for my brittle hair! My hair was severely damaged, and the first 4 applications really helped avoid a big(ger) chop. I bought the kit with the anti-residue charcoal shampoo and the deep conditioner, but I believe the shampoo can be easily substituted. The hair mask is very effective, though.

  • My hairdresser recommended these to me for my colored hair and I love the line of products. It’s so much easier to just use one leave in conditioner + hair oil step in comparison to the many olaplexes. I just wish they sold larger bottles even for the price.

  • I saw the hype behind the leave-in treatment and as someone REALLY prone to split ends and damaged hair even though I don't color or use heat on it much, I was excited to try this out. I emulsified the product as recommended to activate it, but honestly, I really don't notice a difference. Have been using it regardless at least once a week for the past 2 months to use up my bottle, but I can't say I've noticed any sort of difference in my hair health.

  • This stuff is amazing! Everyone should own a bottle of it. I use the detox shampoo first and than the k18 mask leave on for about 10 minutes (though you only need about 4min.) than I put in a leave in conditioner from biolage or redkin. If k18 isn't working for you than use a detox shampoo first to really clean your hair/scalp. The cons are definitely the price being expensive and the fact my hair feels like straw immediately after use but a few minutes after it does get soft. My hair dresser is the one who recommended it to me. I was using olaplex and didn't see any amazing changes unfortunately.

  • I had received a free sample of the k18 leave in conditioner and I LOVED it so I purchased the full size. Not sure what happened to the formula. It didn’t seem to work as well and it weighed down my hair after only one day. The full size doesn’t last that long and it’s very expensive.

    Feedback

    Larger bottles, more product.