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Infographic showing magnified liquid drops next to descriptions of four hair growth ingredients: Redensyl, Procapil, Capixyl, and Caffeine.A smiling woman with brown hair holds up a bottle of Kiierr Multi Peptide Hair Growth Serum.A bottle of Kiierr hair growth serum surrounded by images of its 12 key ingredients.

#1 DOCTOR RECOMMENDED

HAIR GROWTH BRAND ·

#1 DOCTOR RECOMMENDED

HAIR GROWTH BRAND ·

bestseller

clinically formualted

Multi-Peptide Hair Growth Serum

Reactivate. Strengethen. Grow.

4.9 · 509 reviews

90 day money-back guarantee

A lightweight, leave in scalp serum powered by 12 active ingredients—including Redensyl®, Procapil®, Capixyl™ and caffeine—to support fuller, stronger hair and help reduce visible shedding.

Clinically formulated for follicle activation.

Try it for 90 days, completely risk-free.

Just need one? Buy once — $49.99 + shipping

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90 Day Guarantee

Clinicians' Choice

1022 clinicians recommend Kiierr on FrontrowMD without compensation.

WHAT TO EXPECT

Weeks 2–4

Less shedding

Weeks 5–8

Stronger strands

Weeks 8–12

Visible fullness

A before and after comparison showing hair regrowth on the crown of a man's head.Close-up before and after photos of a woman's hairline, showing increased hair density and regrowth at the temple.A before and after comparison showing hair regrowth on the crown of a man's head.A side-by-side comparison of the top of a person's head, showing thinner hair on the left and fuller hair on the right.A before and after comparison of a person's hair, showing increased thickness and coverage on the right.A before and after comparison of a woman's hair, showing increased volume and scalp coverage.A side-by-side comparison of a man's hairline, showing thinner hair on the left and thicker hair on the right.A before and after comparison of a woman's scalp, showing increased hair fullness and a richer color.A before-and-after comparison of the top of a head, showing thinning hair on the left and fuller hair on the right.
A before and after comparison showing hair regrowth on the crown of a man's head.Close-up before and after photos of a woman's hairline, showing increased hair density and regrowth at the temple.A before and after comparison showing hair regrowth on the crown of a man's head.A side-by-side comparison of the top of a person's head, showing thinner hair on the left and fuller hair on the right.A before and after comparison of a person's hair, showing increased thickness and coverage on the right.A before and after comparison of a woman's hair, showing increased volume and scalp coverage.A side-by-side comparison of a man's hairline, showing thinner hair on the left and thicker hair on the right.A before and after comparison of a woman's scalp, showing increased hair fullness and a richer color.A before-and-after comparison of the top of a head, showing thinning hair on the left and fuller hair on the right.

90 day guarantee

Regrow hair or it's free

If you don't see thicker, fuller hair within 90 days, we'll refund you in full. See policy for details.

AS SEEN IN

The MSN logo, which features a butterfly symbol followed by the letters msn.
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See the difference for yourself.

Verified customer before & after photos — unretouched, unfiltered.

The Ultimate Hair Growth Serum

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Clinically formulated for hair growth

Reduces shedding

Helps block DHT

Designed to complement LLLT

A white frosted bottle of Kiierr Multi Peptide Hair Growth Serum Roll-On on a white background.

Kiierr

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Ingredients backed by research.

Clinically supported ingredients reawaken dormant follicles & rebuild visible thickness.

ALL NATURAL

Clinically SUPPORTED

Real data. Real growth.

Real data. Real growth.

CUSTOMER SURVEY RESULTS

Kiierr Serum

+39 hairs/cm²

Placebo

+3 hairs/cm²

Terminal hair count increase

*In customer reported results over 6+ months, Kiierr Serum users saw approximately 39+ new hairs per cm² compared to placebo.

CUSTOMER SURVEY RESULTS

+93

%

PLACEBO

KIIERR

STRONGER, HEALTHIER HAIR

after 90 days of use*

Trusted by 125k+ Happy Customers

4.8 (509 reviews)

A before and after comparison showing hair regrowth on the crown of a man's head.

David R.

I'd been losing ground at my hairline for years and tried everything with minimal results. Around week 10 with Kiierr I noticed the temples starting to fill back in and my overall density looked visibly improved for the first time.

Close-up before and after photos of a woman's hairline, showing increased hair density and regrowth at the temple.

Natalie R.

My temples had been thinning for about two years and nothing I tried made any real difference. After 3 months using the comb and serum together consistently I can see new growth filling in at both temples. The comb makes it so easy to apply the serum exactly where you need it.

A before-and-after photo showing significant hair regrowth and thickness on the crown of a person's head.

Linda H.

I assumed the thinning along my part was just something I had to accept with age. After 3 months using the comb and serum together my part looks noticeably narrower and my hair feels much thicker at the root than it has in years.

A before and after comparison of a woman's hair, showing increased volume and scalp coverage.

Jennifer L.

My hair had become so thin and brittle over the past few years that I was genuinely scared every time I brushed it. I started using the Kiierr comb with the serum nightly and within about 6 weeks I noticed significantly less breakage. By month 3 my hair felt stronger at the root and visibly thicker overall.

A before and after comparison of a person's hair, showing increased thickness and coverage on the right.

Marc T.

After a prolonged illness my shedding was significant and my doctor said to be patient. I started using Kiierr during recovery and by month 4 the shedding had slowed considerably and new growth was visibly coming through my crown.

A before-and-after comparison of the top of a head, showing thinning hair on the left and fuller hair on the right.

Kevin T.

Lost a lot of density across my whole scalp over the past few years. Used the comb with the serum 4 times a week and by week 12 my barber actually commented that my hair looked thicker. That was all the proof I needed.

A before and after comparison of a woman's scalp, showing increased hair fullness and a richer color.

Karen B.

My hair thinned rapidly during menopause and nothing I tried made a dent. After about 12 weeks with the Kiierr system I could see clear regrowth along my hairline and my ponytail felt noticeably fuller than it had in years.

A side-by-side comparison of the top of a person's head, showing thinner hair on the left and fuller hair on the right.

Nadia C.

My part had been widening gradually for about three years and I tried every serum and supplement out there. What I liked about the Kiierr system is that the comb actually gets the serum to the scalp instead of just sitting on top of your hair. After about 10 weeks my part is visibly narrower and I feel so much more confident pulling my hair back. Wish I had found this sooner.

A side-by-side comparison of a man's hairline, showing thinner hair on the left and thicker hair on the right.

Brian M.

I started noticing my front hairline thinning in my early 40s and honestly just accepted it. A friend mentioned the Kiierr system so I figured I'd try it. Used the comb with the serum every other night for about 10 weeks and the difference at my hairline is genuinely noticeable. Wasn't expecting much but I'm a convert.

A side-by-side comparison showing the back of a man's head, with hair appearing thicker on the right.

Darren W.

Thinning at the crown runs in my family and I knew it was coming. I've been using the Kiierr comb and serum for about 4 months now targeting my crown specifically. The red light and massage combo feels like it's actually doing something and the before and after photos I've been taking confirm it. Solid product.

A before and after comparison showing hair regrowth on the crown of a man's head.

David R.

I'd been losing ground at my hairline for years and tried everything with minimal results. Around week 10 with Kiierr I noticed the temples starting to fill back in and my overall density looked visibly improved for the first time.

A before and after comparison of a person's hair, showing increased thickness and coverage on the right.

Marc T.

After a prolonged illness my shedding was significant and my doctor said to be patient. I started using Kiierr during recovery and by month 4 the shedding had slowed considerably and new growth was visibly coming through my crown.

A side-by-side comparison of a man's hairline, showing thinner hair on the left and thicker hair on the right.

Brian M.

I started noticing my front hairline thinning in my early 40s and honestly just accepted it. A friend mentioned the Kiierr system so I figured I'd try it. Used the comb with the serum every other night for about 10 weeks and the difference at my hairline is genuinely noticeable. Wasn't expecting much but I'm a convert.

A before and after comparison of a woman's hair, showing increased volume and scalp coverage.

Jennifer L.

My hair had become so thin and brittle over the past few years that I was genuinely scared every time I brushed it. I started using the Kiierr comb with the serum nightly and within about 6 weeks I noticed significantly less breakage. By month 3 my hair felt stronger at the root and visibly thicker overall.

A side-by-side comparison of the top of a person's head, showing thinner hair on the left and fuller hair on the right.

Nadia C.

My part had been widening gradually for about three years and I tried every serum and supplement out there. What I liked about the Kiierr system is that the comb actually gets the serum to the scalp instead of just sitting on top of your hair. After about 10 weeks my part is visibly narrower and I feel so much more confident pulling my hair back. Wish I had found this sooner.

A before-and-after photo showing significant hair regrowth and thickness on the crown of a person's head.

Linnda H.

I assumed the thinning along my part was just something I had to accept with age. After 3 months using the comb and serum together my part looks noticeably narrower and my hair feels much thicker at the root than it has in years.

A before and after comparison of a woman's scalp, showing increased hair fullness and a richer color.

Karen B.

My hair thinned rapidly during menopause and nothing I tried made a dent. After about 12 weeks with the Kiierr system I could see clear regrowth along my hairline and my ponytail felt noticeably fuller than it had in years.

Close-up before and after photos of a woman's hairline, showing increased hair density and regrowth at the temple.

Natalie R.

My temples had been thinning for about two years and nothing I tried made any real difference. After 3 months using the comb and serum together consistently I can see new growth filling in at both temples. The comb makes it so easy to apply the serum exactly where you need it.

A before-and-after comparison of the top of a head, showing thinning hair on the left and fuller hair on the right.

Kevin T.

Lost a lot of density across my whole scalp over the past few years. Used the comb with the serum 4 times a week and by week 12 my barber actually commented that my hair looked thicker. That was all the proof I needed.

A side-by-side comparison showing the back of a man's head, with hair appearing thicker on the right.

Darren W.

Thinning at the crown runs in my family and I knew it was coming. I've been using the Kiierr comb and serum for about 4 months now targeting my crown specifically. The red light and massage combo feels like it's actually doing something and the before and after photos I've been taking confirm it. Solid product.