K18

K18 Molecular Repair Hair Oil.

Haircare

About this product

A hair oil formulated to condition and moisturize hair, providing hydration and shine.

Full ingredients

Caprylyl Caprylate/Caprate, Squalane, Persea Gratissima (Avocado) Oil, Helianthus Annuus (Sunflower) Oil, C13-15 Alkane, Undecane, Benzyl Alcohol, Tridecane, Castor Isostearate Succinate, Propanediol, SH-Oligopeptide-78 (K18 Peptide™), Fragrance (Parfum), Tocopherol, Cinnamal, Hexyl Cinnamal, Limonene, Linalool

Guru Score

74%

Mixed

4 experts · Moderate agreement

What they liked

Lightweight without greasy residue
Works for longer hair

What they flagged

Nothing. None of the experts who reviewed it raised a problem.

What the gurus are saying

This lightweight oil earns praise for not weighing hair down or leaving a greasy feel, a rare quality in a category where many formulas coat strands and dull them. As hair length increases, having a quality oil that doesn't drag becomes essential, and this one delivers exactly that without the heaviness that keeps people from reaching for oils.

Synthesized from 4 expert reviews · most recent take September 2026

Type

HaircareOil

Key actives

Vitamin EPeptides Squalane

Formula notes

Contains fragranceNo drying alcohol

Where to buy

Sephora → Amazon → Google → iHerb →

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Scan it in the shopFree iPhone app. Scores in the aisle.

What the gurus are saying.

Every take we've logged from this product's reviews across YouTube. Click any row to watch the moment they said it.

All takes Yay takes Nay takes Mixed takes Hide sponsored

Beyond50Skin

32k subs

~Nay

"One is the new K18 hair oil. Honestly, this just didn't work out. It weighed my hair down. I just didn't like the feel of it. I usually do an oil pre-treat in the evenings, kind of some few drops of oil and then put on kind of a sleep cap. This just wasn't for me."

Doctorly

3.59M subs

~Yay

"I really like the one from K18. I think it's really nice and lightweight, it doesn't make my hair feel greasy or oily, and my wife likes it too. I don't like things that are too heavy or greasy in my hair, and this one doesn't do that."

Dr. Jenny Liu

323k subs

~Yay

"I really like K18, they're biomimetic hair science Molecular Repair Hair Oil. This one is great because it reduces frizz, you can use it on wet or dry hair and also offers great heat protection. Word of caution: few drops goes a long way. I made the mistake of literally drenching my entire palm and then my hair, which is pretty coarse and can eat up quite a bit of oil, but it felt really greasy afterwards. So all you need is a little bit."

All 3 takes from Dr. Jenny Liu

Dermatologist Fall Hair Care tips | Dr. Jenny Liu

"The first styling product I recommend is from K18 and it's their K18 Molecular Repair Hair Oil. Often oils can be a little bit too heavy and weigh your hair down but this one is not. It's very light and liquidy and contains the proprietary K18 peptide, and not only does it help to soften hair and reduce frizz but also offers great heat protection. You can use it on dry or wet hair."

Dermatologist’s tips on How to minimize hair breakage | Dr. Jenny Liu

Holiday Gift Set Ideas | Dr Jenny Liu

"The repair oil that you can use afterwards on dry or damp hair that also helps to smooth hair, reduces frizz and also acts as a heat protectant. One thing I'll caution you is that this oil is rich and a little bit goes a long way and really all you need, even for my hair that's pretty long and coarse, like I feel like four drops really will seal the deal for me. In fact, I one time got overzealous and used a pump full and my hair just felt extra greasy."

Alexandra Anele

1.44M subs

~Yay

"The hair oil is something that I never used and then now that my hair is getting longer I'm realizing how important it is. Don't skip out on a hair oil. That's a really good one, you guys."

What the evidence says.

Independent of what the gurus think, this is what the published research supports about the main active ingredients here.

Humectants and emollients

Ingredients like these draw water into the surface layers and slow how fast it leaves. The evidence is for comfort, softness and hydration rather than for changing the structure of the skin.

Source: DermNet

Peptides

Peptides are short protein fragments meant to signal repair. The evidence for them is thinner than for retinoids or vitamin C, and it varies a lot by the specific peptide, so the category is more promising than proven.

Source: NIH, National Library of Medicine

Vitamin E

Vitamin E is an antioxidant, and it is often in a formula to keep the other ingredients stable rather than as the active itself. It pairs well with vitamin C, though on its own the evidence for visible change is limited.

Source: NIH, National Library of Medicine

Frequently asked.

What is K18 Molecular Repair Hair Oil?

A hair oil formulated to condition and moisturize hair, providing hydration and shine.

Is K18 Molecular Repair Hair Oil worth it?

The gurus mostly approve it, but with enough reservations to keep it in the middle at a Guru Score of 74%.

What is K18 Molecular Repair Hair Oil's Guru Score?

K18 Molecular Repair Hair Oil holds a Guru Score of 74%. That is our read on how warmly the experts talk about it, based on the verdicts of 4 expert reviewers we have collected.