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★★★★★ 4.9 from 2,140 fill clients

Fuller lashes in 5 minutes a day — without stopping extensions.

The extension-safe peptide serum built for the gap between fills — so every appointment builds on stronger lashes, not thinner ones.

  • Extension-safe formula — apply the same day as a fill, no oils that break down adhesive
  • Acetyl Hexapeptide-8 and hydrating actives support lash resilience and fullness over time
  • One swipe each evening — most clients notice a difference by their second fill (2–3 weeks)
  • Works for thinning lash lines, sparse spots, and post-extension shedding

30-day money-back guarantee · Ships in 24 hours

Extension-safe, tech-approvedCruelty-freeDermatologist tested
Will this loosen my extensions?

No — KØS is formulated without oils or silicones known to break down lash adhesive, so it's safe to apply the same day as a fill.

How fast will I actually see results?

Most clients notice a difference by their second fill appointment (roughly 2–3 weeks), with fuller results building through fill three.

What if it doesn't work for me?

You're covered by a 30-day guarantee — if you don't see a difference, we'll refund you, no questions asked.
  • 2,140+ fill clients
  • 4.9 average rating
  • 92% saw results by fill 2
  • Tech-approved extension-safe
  • 30-day guarantee

Real fill cycles

Proof, not promises.

★★★★★

“My tech asked what changed at fill three. I hadn't told her yet.”

— Mira, 27

★★★★★

“First serum that didn't fight with my extensions.”

— Sofia, 31

★★★★★

“Fills last longer now — more real lash to hold the extension.”

— Priya, 24

★★★★★

“60 seconds a day. That's genuinely it.”

— Hana, 26

★★★★★

“I'd accepted thin natural lashes as the cost of extensions. It wasn't.”

— Alexa, 29

★★★★★

“Two other serums didn't work with extensions. This one does.”

— Jordan, 33

★★★★★

“Noticeable by fill two, obvious by fill three.”

— Ruth, 25

★★★★★

“My lash tech recommends it to other clients now.”

— Nadia, 30

Why it works

Damage starts under the bond — so that's where KØS works.

Extension adhesive sits directly on the natural lash. Repeated fills without recovery time thin the follicle underneath — long before it's visible. KØS's peptide complex is absorbed at the follicle base, working in the days between fills instead of fighting the bond itself.
The lash line is one of the few places where daily peptide delivery actually reaches the follicle without disrupting a barrier — and it's engineered around, not despite, the fill schedule.

— Formulated with input from certified lash technicians and cosmetic chemists

Inside the formula

Three actives. Nothing that fights your extensions.

Peptide Complex (Matrixyl-type)

Signals the follicle to extend its growth phase, supporting thicker, longer natural lash growth over time.

Referenced in peer-reviewed dermal peptide studies

Hydrolyzed Keratin

Rebuilds structural protein along the lash shaft, reducing breakage from repeated fill removal.

Standard in post-procedure hair/lash recovery formulas

Panthenol (Pro-Vitamin B5)

Soothes the lash line after fills and locks in moisture without any oil residue that could loosen adhesive.

Common dermatologist-recommended barrier support ingredient

How it stacks up

Most growth serums weren't built with extensions in mind. Kosvéra was.

FeatureKosvéraTypical growth serumsNo serum
Safe to apply over fresh fillsYesOften not — oils break down adhesiveN/A
Timed to the fill cycleYes — nightly, 2–3 week cycleNot formulated around fillsNo plan
Conditions the lash fiberYes — oat protein + olive glyceridesRarely addressedDamage compounds
Daily time cost60 seconds, PMVaries, often more—
Guarantee30 daysVaries—

Safe to apply over fresh fills

KosvéraYes
Typical growth serumsOften not — oils break down adhesive
No serumN/A

Timed to the fill cycle

KosvéraYes — nightly, 2–3 week cycle
Typical growth serumsNot formulated around fills
No serumNo plan

Conditions the lash fiber

KosvéraYes — oat protein + olive glycerides
Typical growth serumsRarely addressed
No serumDamage compounds

Daily time cost

Kosvéra60 seconds, PM
Typical growth serumsVaries, often more
No serum—

Guarantee

Kosvéra30 days
Typical growth serumsVaries
No serum—

Questions, answered

Everything before your next fill.

Yes — it's formulated without oils or silicones that interfere with lash adhesive, so it's safe to apply right after an appointment.
In the evening, every night — one swipe along the lash line as part of your PM routine.
Most clients report visible change by their second fill (roughly 2–3 weeks), with fuller results building through the third fill cycle.
Many of our clients say their tech asks what changed before they bring it up — stronger, more resilient natural lash is usually the first thing techs notice at rebooking.
You're covered by a 30-day money-back guarantee — no questions asked.
Yes, Kosvéra is fully cruelty-free and never tested on animals.
Bundle pricing ends with this fill cycle

Your next fill, covered

Start before your next appointment.

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