Bleach blonde hair before and after results using k18.

Red curly hair before and after results using k18.

dark coily hair before + after styling with k18 hair products.

Grey curly hair before and after results using k18.

highly concentrated formula. start with 1-3 drops, build as needed.

silicone-free weightless oil is powered: K18PEPTIDE(TM), Avocado Oil, Sunflower Oil, Hemisqualane + Squalane.

how damage + frizz related? before + after of outer and inner layer

Mini versus full size product comparison

4.8

Rated 4.8 out of 5 stars

832 Reviews

Molecular repair hair oil

Name: Molecular Repair Hair Oil 30 mL
Brand: K18Hair
SKU: K18-32011
Price: 65.00 GBP
Availability: InStock

Weightless oil that strengthens, repairs damage + reduces frizz

Molecular Repair Hair Oil 30 mL £65.00

Description

This biotech-engineered weightless oil works on all hair types to strengthen, repair damage, reduce frizz at two levels of the hair fiber, and improve shine.

clinically proven damage repair
24-HR frizz control
104% more shine
78% reduction in split ends
232°C heat protection

how to use

Apply to damp, towel-dried hair before styling, or on dry hair as a finisher. Highly concentrated formula. Start with 1-3 drops and build as needed.

Use on damp hair for: strengthening benefits and to reduce frizz during air-dry or styling.

Use on dry hair to: smooth frizz and flyaways, as a finisher to add shine.

Apply to damp hair from mid-lengths to ends. For strengthening benefits from the K18PEPTIDE™ wait 4 minutes before styling.
Apply to dry hair as a finisher.

Pro Tip - If using the K18 molecular repair mask, apply the mask first on clean, damp hair, then wait 4 minutes. Apply the molecular repair hair oil, and wait 4 minutes for maximum strengthening results.

more to know

Strengthening, smoothing hair oil works on two levels of the hair fiber to fight frizz.

The K18PEPTIDE™ works to address deeper-level damage that causes frizz—repairing and strengthening damage at the innermost layer of hair to reverse damage that leads to frizz.

On the surface of hair, natural oils like avocado and sunflower oil, and hemisqualane and squalane nourish while smoothing frizz + flyaways to improve color vibrancy, enhance shine, and provide 232°C heat protection.

Clinically proven to repair damaged hair.*
24-HR frizz control*
104% increase in shine*
78% reduction in split ends*
232°C heat protection*

*Disclaimers

key benefits

This silicone-free oil fights frizz differently by addressing the damage that causes frizz long-term and immediately smoothing frizz + flyaways.

Reverses frizz-causing damage: Works at the molecular level to repair damaged hair, which is more susceptible to frizz.
Reduces frizz + flyaways: Natural oils work on the surface of the hair to smooth the cuticle + soften without weighing hair down.
Enhances shine + color vibrancy: Nourished, moisturized hair reflects higher shine and boosts color dimension.
Delivers heat protection: to prevent further frizz-causing damage up to 232°C.

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, Fragrance (Parfum), Tocopherol, Cinnamal, Hexyl Cinnamal, Limonene, Linalool.

pairs well with

full-size leave-in molecular repair hair mask

4.7

Rated 4.7 out of 5 stars

7,826 Reviews

4-minute leave-in treatment to reverse hair damage

AstroLift™ reparative volume spray

4.6

Rated 4.6 out of 5 stars

319 Reviews

Interdimensional biotech reverses bounce-depleting damage for 2-day hold

Description

This biotech-engineered weightless oil works on all hair types to strengthen, repair damage, reduce frizz at two levels of the hair fiber, and improve shine.

got questions?

Get started here.

Can i use the molecular repair hair oil instead of the mask?

We recommend using the oil with the mask for maximum molecular repair with additional styling benefits. Think of the mask as a damage repair treatment after washing your hair. The oil is for smoothing, styling and strengthening after the mask, and can be used on damp and dry hair.

Does the molecular repair hair oil provide heat protection?

Yes, this oil provides heat protection up to 232°C.

Will the molecular repair hair oil leave buildup or weigh down my hair?

No, it will not leave buildup or weigh down your hair. This weightless oil is powered by intentional ingredients to reduce frizz-causing damage on the molecular level inside the hair fiber, while natural oils work on the surface of hair without weighing it down.

Plus, you don’t need much of this highly concentrated formula to see results, just use 1-3 drops and build as needed. If you’re concerned about buildup, use our detox shampoo to remove 99% of product buildup after just 1 wash*.
*Disclaimers

Will the mask block the molecular repair hair oil from penetrating?

No, the mask will not block the molecular repair hair oil from penetrating. The mask is a highly concentrated treatment without any fillers so it won’t block the oil from penetrating. Like layering different skincare products, the oil can be layered on top of the mask without impacting its performance.

Can I mix the oil and mask together?

Instead of mixing the oil and mask together, get the most effective repair and styling benefits by using the mask first, waiting 4 minutes, and then applying the oil.

immediate + lasting frizz control

Boost shine and seal split ends on all hair types—weightlessly.

before

after

"I normally don't use hair oils as my hair gets naturally oily....I loved the end result! I will officially be adding this hair oil to my routine"
- Fabiola N.

before

after

"I use this alllll the time. It's truly saved my hair....And it's so gorgeous and shiny and the thickness is returning nicely." - Emma L.

before

after

"It makes my hair much smoother after it’s been so damaged."
- Crystal A.

before

after

"So far so good, used it around 4 times and my hair looks shinier and has less frizz"
- Anel

clinically proven smoothness

hour frizz control*

more shine*

reduction in split ends*

degree C heat protection*

how to use molecular repair oil

Highly concentrated formula. Start with 1-3 drops and build as needed.

1. Apply 1-3 drops to towel-dried hair from mid-lengths to ends.

2. For strengthening benefits from the K18PEPTIDE™, wait 4 minutes before styling.

3. Apply 1-3 drops to dry hair as a finisher.

feel what's possible with K18

See how K18 unlocks our community's expression

4.8

Rated 4.8 out of 5 stars

Based on 832 reviews

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832 reviews

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Sami A. N. A.
Verified Buyer
Reviewing
hair oil deluxe sample
I recommend this product
Rated 5 out of 5 stars
8 minutes ago
AMAZING
este coso resucitó mi cabello, los resultados son instantáneos y todo el mundo me dice que tengo cabello de Barbie desde que lo uso 🩷
Was this helpful?
Savannah R.
Verified Buyer
Reviewing
hair oil sample
I recommend this product
Rated 5 out of 5 stars
2 days ago
Love love love
So light and hydrating
Was this helpful?
KU
K18Hair UK
Yesterday
Thank you so much for this amazing review, Savannah! We're absolutely thrilled to hear that you love our hair oil sample and that it's delivering that perfect lightweight, hydrating feel! It's wonderful that you're experiencing such fantastic results with the formula - that balance of being light yet deeply hydrating is exactly what we hoped to achieve! Your feedback truly means the world to us, and we're so grateful to have you as part of our K18 community!
Christine C.
Verified Buyer
Reviewing
Molecular Repair Hair Oil 30 mL
I recommend this product
Age 55 - 64
Hair Concern Dryness, Split-Ends, Chemical damage, Color-care, Heat damage
Hair Type Fine/Thin
My Results Visible Difference, Bouncy Hair, Stronger Hair, Less Breakage, Soft Touchable Hair
Rated 5 out of 5 stars
3 days ago
Molecular Repair Oil
The K18 Molecular Repair Hair Oil is a lightweight, silicone-free oil that delivers real smoothing and frizz control while helping strengthen the hair from the inside out. It’s one of the few oils that feels treatment-first, styling-second — meaning it improves the hair’s condition over time, not just the way it looks.
Was this helpful?
KU
K18Hair UK
Yesterday
Thank you so much for this incredible review, Christine! We're absolutely thrilled to hear that you're experiencing the true power of our Molecular Repair Hair Oil - that perfect combination of lightweight smoothing and frizz control while actually strengthening your hair from within! It's wonderful that you've noticed how this oil is truly treatment-first, styling-second, which is exactly what we aimed to achieve with this silicone-free formula. Your feedback about seeing real improvement in your hair's condition over time, not just temporary styling benefits, truly means the world to us! We're so grateful to have you as part of our K18 community!
Jodie V.
Verified Buyer
Reviewing
hair oil deluxe sample
I recommend this product
Rated 5 out of 5 stars
2 weeks ago
Best hair oil out there
Lightweight ,not greasy and leaves your hair super soft and silky!!!!its a must.
Was this helpful?
KU
K18Hair UK
2 weeks ago
Thank you so much for your incredible review, Jodie! We're absolutely thrilled to hear that our Hair Oil Deluxe Sample is hitting all the right notes for you - lightweight, non-greasy, and delivering that super soft and silky finish! There's no better compliment than knowing our formula is giving you that perfect balance of nourishment without any heaviness. We love that it's earned "must have" status in your routine! ❤️
Mrs. L.
Verified Buyer
Reviewing
Mini molecular repair hair oil 10 mL
I recommend this product
Age 25 - 34
Hair Concern Chemical damage
Hair Type Fine/Thin
My Results Smoother Hair, Visible Difference
Rated 5 out of 5 stars
1 month ago
Perfect Travel Size
It’s the perfect size for TSA approval. It smells really nice and not heavy on my fine hair. I recommend it
Was this helpful?
KU
K18Hair UK
1 month ago
Thank you so much for your incredible review, Mrs.! We're absolutely thrilled to hear that our Mini Molecular Repair Hair Oil is the perfect travel companion with its TSA-friendly size - there's no better compliment than knowing our molecular repair technology is delivering such amazing results for your fine hair while being lightweight and beautifully scented! ❤️