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HAIR SCALP SERUM

4.4
(322)

Lightweight serum to reduce visible shedding + boost density.

  • Age-Reversal Peptide
  • Thickening
  • Color Safe
  • Non Greasy
Set of black hair serum bottles with dropper on a light beige background. Contains descriptive text stating Bottle size may vary. The 6-month supply will always come with 150mL of the OS-01 HAIR serum.
Set of black hair serum bottles with dropper on a light gray background contains descriptive text stating bottle size may vary, the 3 month supply will always come with 150mL of the OS-01 HAIR serum.
Black dropper bottle with 'ONE SKIN' branding on a beige background
A cluster of clear, bubble-like droplets with silver outlines arranged on a plain white background.
A bottle of One Skin OS-01 Hair Peptide Scalp Serum with a glass dropper above it, set against a light gray background with promotional text highlighting hair density, reduced shedding, and lightweight water-based texture.
Close-up of a person applying OS-01 HAIR SCALP SERUM, with a hand holding a glass dropper above the scalp and text reading '43% increase in hair thickness after 6 months'.
Before-and-after comparison of a person's hairline showing increased hair density after 6 months, with text stating '40% increase in hair density'.
A black background with a small clear oval droplet or capsule in the center and white text listing ingredients and benefits: Panax ginseng root extract, biotin, and fisetin.
A close-up of a petri dish filled with transparent gel, with text reading 'OS-01 PEPTIDE' and descriptive copy about reversing skin's visible biological age.
A simple infographic on a light gray background showing three labeled silhouettes: a pipette labeled KEEP, a reusable glass bottle labeled KEEP, and a refill cartridge labeled DISCARD. The refill cartridge is shown larger and in black silhouette, with small red and green label boxes and black text underneath.
Set of black hair serum bottles with dropper on a light beige background. Contains descriptive text stating Bottle size may vary. The 6-month supply will always come with 150mL of the OS-01 HAIR serum.
Set of black hair serum bottles with dropper on a light gray background contains descriptive text stating bottle size may vary, the 3 month supply will always come with 150mL of the OS-01 HAIR serum.
Black dropper bottle with 'ONE SKIN' branding on a beige background
A cluster of clear, bubble-like droplets with silver outlines arranged on a plain white background.
A bottle of One Skin OS-01 Hair Peptide Scalp Serum with a glass dropper above it, set against a light gray background with promotional text highlighting hair density, reduced shedding, and lightweight water-based texture.
Close-up of a person applying OS-01 HAIR SCALP SERUM, with a hand holding a glass dropper above the scalp and text reading '43% increase in hair thickness after 6 months'.
Before-and-after comparison of a person's hairline showing increased hair density after 6 months, with text stating '40% increase in hair density'.
A black background with a small clear oval droplet or capsule in the center and white text listing ingredients and benefits: Panax ginseng root extract, biotin, and fisetin.
A close-up of a petri dish filled with transparent gel, with text reading 'OS-01 PEPTIDE' and descriptive copy about reversing skin's visible biological age.
A simple infographic on a light gray background showing three labeled silhouettes: a pipette labeled KEEP, a reusable glass bottle labeled KEEP, and a refill cartridge labeled DISCARD. The refill cartridge is shown larger and in black silhouette, with small red and green label boxes and black text underneath.

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  • Certified cruelty-free by The Leaping Bunny

  • Approved by the National
Eczema Association

  • Certified plastic neutral in partnership with RePurpose

  • Certified cruelty-free by The Leaping Bunny

  • Approved by the National
Eczema Association

  • Certified plastic neutral in partnership with RePurpose

  • Certified cruelty-free by The Leaping Bunny

  • Approved by the National
Eczema Association

  • Certified plastic neutral in partnership with RePurpose

Details
  • Our proprietary OS-01 Senescence-Blocking Peptide™ reverses the visible effects of cellular senescence (dysfunction) at the hair follicle, where age-related thinning begins
  • Supports a healthy hair cycle for less visible shedding, and thicker, fuller hair over time¹
  • Clinically validated to increase hair density by +40% and thickness by +43%¹
  • Lightweight, fragrance-free, and dermatologist-tested formula dries residue-free

 

Clinical proof
  • +40% increase in hair density, shown in 81% of users, after 6 months¹
  • +43% increase in hair thickness, shown in 78% of users, after 6 months¹
  • 75% observed visible new hair after 3 months¹
  • 72% reported less visible shedding after 6 months¹

The Clinical Studies

Efficacy study

A 6-month double-blind, third-party clinical study evaluated the effects of OS-01 HAIR SCALP SERUM on hair density, thickness, shedding, and scalp health in 32 participants (23 female, 9 male) ages 27–55, using OS-01 HAIR SCALP SERUM twice daily and dermarolling once daily. Hair parameters including hair growth, thickness, density, and hair cycle were measured via HairMetrix® clinical photography, trichoscopy, and phototrichogram. Expert graders also evaluated hair parameters and participant provided subjective self-reported feedback.

The results1:

  • 81% showed a +40% improvement in hair density after 6 months
  • 78% showed a +43% improvement in hair thickness after 6 months
  • 72% reported less visible shedding after 6 months
  • 75% reported visibly fuller hair after 3 months
  • 75% observed the appearance of new hair after 3 months
  • 75% reported stronger feeling hair after 6 months
  • 72% said existing hair grew visibly faster after 6 months

Microbiome study

A 6-month third-party study by HelloBiome with 30 participants evaluated the impact of OS-01 HAIR SCALP SERUM on the scalp microbiome. Participants showed significant improvements in bacterial diversity and an increase in M. globosa abundance, resulting in a lower M. restricta/M. globosa ratio—a marker associated with improved scalp health.

Safety Studies

OS-01 HAIR SCALP SERUM is dermatologist tested, suitable for sensitive skin, fragrance free, and formulated without parabens, sulfates, phthalates, or other common irritants. Based on its formula and clinical testing, it has been awarded the National Eczema Association Seal of Acceptance™.

Our commitment to the scientific process

OneSkin products are validated with a rigorous process from the lab to the clinic: Lab testing on human skin to evaluate the effect on the cellular level, consumer testing with real users to ensure optimal texture and feel, and third-party clinical studies to evaluate the effect on the human level over time.
Ingredients

Formulated without
Our products are formulated without fragrance, parabens, sulfates, lanolin, MCI/MI, DEA, heavy metals, talc, petrolatum/paraffin/mineral oil, gluten, phthalates, and PFAs. We also avoid unnecessary emulsifiers, preservatives, and solvents.

Ingredients
Water, Glycerin, 1,2-Hexanediol, Butylene Glycol, Hydroxyacetophenone, Panthenol, Inulin, Helianthus Annuus (Sunflower) Sprout Extract, Cellulose Gum, Alpha-Glucan Oligosaccharide, Tetrasodium Glutamate Diacetate, Propanediol, Morus Nigra Leaf Extract, Arginine, Acetyl Tyrosine, Rehmannia Chinensis Root Extract, Pentylene Glycol, Sodium PCA, Erythritol, Chondrus Crispus, PEG-12 Dimethicone, Oryza Sativa (Rice) Bran Water, Decapeptide-52*, Calcium Pantothenate, Zinc Gluconate, Sodium Benzoate, Niacinamide, Ornithine HCl, Caprylyl Glycol, Polyquaternium-11, Citrulline, Hydrolyzed Soy Protein, Xanthan Gum, Glucosamine HCl, Disodium Succinate, Fisetin, Raspberry Ketone, Sodium Benzoate, Citric Acid, Potassium Sorbate, Arctium Majus Root Extract, Panax Ginseng Root Extract, Biotin.
*OS-01 Peptide

How to use

Fill the glass pipette with serum by squeezing the applicator bulb (the pipette will be about half full). Apply the serum directly to your scalp and massage in to ensure even distribution. We recommend applying two pipettes’ worth (2 squeezes) to the entire scalp during each application. Do not rinse, and style as usual. Use 2x daily on dry or damp hair.

A 50 mL bottle of OS-01 HAIR SCALP SERUM should last approximately 30 days with regular use.

Watch the video →

Complete the Protocol

The only scalp serum to target a key root cause of age-related hair thinning with the OS-01 Peptide™.

Abstract icon of an hour glass with a 3/4 circle around it

Powered by the OS-01 Peptide™

Proven to reverse the visible effects of follicle-cell senescence, supporting hair density and reduced visible shedding.

Abstract icon of a line splitting up a grid of dots

Improves density

Results build with consistent use, including denser, thicker hair after 6 months.1

Abstract icon showing a hair follicle under skin

Reduces visible shedding

Supports a healthy hair cycle at the root, resulting in less visible shedding after 6 months.¹

Lightweight, water-based texture

Fast-absorbing formula dries residue-free and never feels greasy.

Abstract icon of an hour glass with a 3/4 circle around it

Powered by the OS-01 Peptide™

Proven to reverse the visible effects of follicle-cell senescence, supporting hair density and reduced visible shedding.

Abstract icon of a line splitting up a grid of dots

Improves density

Results build with consistent use, including denser, thicker hair after 6 months.1

Abstract icon showing a hair follicle under skin

Reduces visible shedding

Supports a healthy hair cycle at the root, resulting in less visible shedding after 6 months.¹

Lightweight, water-based texture

Fast-absorbing formula dries residue-free and never feels greasy.

OS-01 Peptide logo featuring a solid orange square on the left, followed by the text 'OS-01' in black and 'PEPTIDE' in bold black letters, with a small trademark symbol.

Engineered to reverse skin’s visible biological age.2

Built on over a decade of longevity science, our proprietary OS-01 Peptide™ reverses the visible effects of senescent (dysfunctional) cells that degrade collagen, elastin, hyaluronic acid and barrier strength. The result: skin that looks, feels, and acts younger over time.

Explore the science →

Clinically validated results that build over time

Before-and-after comparison of a person's hairline, showing hair growth progress over 12 weeks. The top panel is labeled 'BEFORE' and shows a thinning hairline outlined in a dotted white shape.

75%

observed the appearance of new hair after 3 months1

Before-and-after comparison of a person's scalp hairline, showing a wider part line and healthier-looking hair after 12 weeks. The top panel is labeled BEFORE and shows darker hair with a visible part line; the bottom panel is labeled AFTER 12 WEEKS and shows a finer, less visible part line.

75%

said their hair appears visibly fuller after 3 months1

A before-and-after comparison of a person's scalp showing hair growth results. The top photo is labeled BEFORE and shows a visible hairline recession with dark hair and a white dotted circle highlighting the scalp.

81%

observed overall improvements in their hair after 3 months1

MONTH 1

Your scalp longevity journey begins

  • The OS-01 Peptide™ gets to work at the follicle immediately
  • Supporting ingredients nourish and calm the scalp
  • Hair feels healthier with each use
MONTH 3

Early results taking hold

  • 75% observed visible new hair after 3 months¹
  • 75% reported visibly fuller hair after 3 months¹
  • Scalp feels balanced and less stressed
MONTH 6

Visibly fuller, denser hair

  • +40% increase in hair density, shown in 81% of users¹
  • +43% increase in hair thickness, shown in 78% of users¹
  • 72% reported decreased visible shedding¹
  • 72% said existing hair grew visibly faster1

Key ingredients

A single clear, teardrop-shaped liquid droplet with a cluster of small bubbles in the center, isolated on a solid black background.
OS-01 Peptide™

Proven to reverse the visible effects of follicle-cell senescence.

Panax ginseng

Supports natural circulation to deliver nutrients to follicles.

Rice bran water + sunflower sprout

A duo of rice bran and sunflower sprout rich in ferulic acid to visibly strengthen and protect hair.

Biotin + fisetin

Helps protect follicles from the visible effects of oxidative stress and visibly strengthen the hair shaft for healthier and stronger-looking hair over time.

Prebiotic complex

A prebiotic duo that supports a balanced scalp microbiome—a key marker of scalp and hair health.

All ingredients

Formulated without
Our products are formulated without fragrance, parabens, sulfates, lanolin, MCI/MI, DEA, heavy metals, talc, petrolatum/paraffin/mineral oil, gluten, phthalates, and PFAs. We also avoid unnecessary emulsifiers, preservatives, and solvents.

Ingredients
Water, Glycerin, 1,2-Hexanediol, Butylene Glycol, Hydroxyacetophenone, Panthenol, Inulin, Helianthus Annuus (Sunflower) Sprout Extract, Cellulose Gum, Alpha-Glucan Oligosaccharide, Tetrasodium Glutamate Diacetate, Propanediol, Morus Nigra Leaf Extract, Arginine, Acetyl Tyrosine, Rehmannia Chinensis Root Extract, Pentylene Glycol, Sodium PCA, Erythritol, Chondrus Crispus, PEG-12 Dimethicone, Oryza Sativa (Rice) Bran Water, Decapeptide-52*, Calcium Pantothenate, Zinc Gluconate, Sodium Benzoate, Niacinamide, Ornithine HCl, Caprylyl Glycol, Polyquaternium-11, Citrulline, Hydrolyzed Soy Protein, Xanthan Gum, Glucosamine HCl, Disodium Succinate, Fisetin, Raspberry Ketone, Sodium Benzoate, Citric Acid, Potassium Sorbate, Arctium Majus Root Extract, Panax Ginseng Root Extract, Biotin.
*OS-01 Peptide

How to apply OS-01 HAIR SCALP SERUM

OS-01 HAIR SCALP SERUM

Write a Review (Opens in a new window)
322 reviews
  • NW
    Nicole W.
    Verified Buyer
    Reviewing
    OS-01 HAIR SCALP SERUM
    I recommend this product
    Rated 4 out of 5 stars
    1 week ago
    Healthy Scalp

    I honestly don’t know if my hair is longer or thicker but I have seen a huge improvement in my scalp health. I didn’t even realize how dry and itchy my scalp was until this serum made it go away! No redness!

    Was this helpful?
    OneSkin
    1 week ago

    Hi Nicole! Thank you so much for your wonderful 4-star feedback about our OS-01 HAIR SCALP SERUM! We're absolutely thrilled to hear that you're loving it - that kind of enthusiastic response really means the world to all of us at OneSkin!

    It's fantastic that you've experienced such a meaningful improvement in your scalp health! The fact that the dryness and itchiness have gone away, and that you're noticing no redness is exactly the kind of tangible difference we hope our science-backed approach delivers. It's amazing how much better your scalp feels when it's actually getting the care it needs!

    We're so grateful that you chose OS-01 HAIR SCALP SERUM for your routine, and we really appreciate you taking the time to share your experience. Your 4-star review truly means so much to us!

  • BD
    Brian D.
    Verified Buyer
    Reviewing
    OS-01 HAIR | 6 Month Supply Refills
    I do not recommend this product
    Rated 2 out of 5 stars
    1 week ago
    Hair subscription

    The 01 Hair serum hasn't helped. I'm not renewing the subscription; however, I have a sufficient amount to last me till year's end, and if anything changes, I'll let you know

    Thank you for your past help

    Brian

    Was this helpful?
    OneSkin
    1 week ago

    Hi Brian,

    Thank you so much for taking the time to share your feedback — we really appreciate your honesty about your experience with OS-01 HAIR.

    We hear you on the serum not delivering the results you were hoping for. We know that when you're investing in a product, especially with a subscription, you're looking for noticeable results that make a real difference. It's completely understandable that you've decided not to renew.

    We also want to thank you for the kind words about our past support — we genuinely appreciate that, and we're grateful you took the time to give the product a try.

    If anything does change or if there's anything we can help with down the road, we're here for you.

    Thanks for being part of OneSkin, Brian!

  • DS
    Deborah S.
    Verified Buyer
    Reviewing
    OS-01 HAIR SCALP SERUM
    I recommend this product
    Rated 5 out of 5 stars
    1 week ago
    Love the title. Says exactly what it is.

    Enjoying the product. After using my scalp no longer feels tight and itchy

    Was this helpful?
  • EJ
    Elizabeth J.
    Verified Buyer
    Reviewing
    OS-01 HAIR | 3 Month Supply Refills
    I recommend this product
    Rated 5 out of 5 stars
    2 weeks ago
    Lightweight, not sticky, and hopefullyeffective!

    I used the OS-01 Hair serum for several months when it was first released but after a time was not consistent with refills. I'm hoping it assists with some hair regrowth as I begin to use it again. The product is odorless, lightweight, and easy to use.

    Was this helpful?
  • J&
    Joe &. I. C.
    Verified Buyer
    Reviewing
    OS-01 HAIR | 3 Month Supply Refills
    I do not recommend this product
    Rated 2 out of 5 stars
    2 weeks ago
    OS-01 Hair

    Gave it a try for 7 months...not expecting much since I'm a 75-year-old male. My understanding is that at that age hair follicles are completely inactive. Have not noticed any new hair growth.

    Was this helpful?
    OneSkin
    2 weeks ago

    Hi Joe,

    Thank you so much for taking the time to share your feedback about OS-01 HAIR — we really appreciate you giving it a try over these past 7 months and being honest about your experience.

    We completely understand how disappointing it must be to use a product consistently and not see the results you were hoping for. When you've invested time and trust in a hair care product, it's really important that you feel like it's making a meaningful difference.

    We also want to share a bit more context on how OS-01 HAIR works, since it may help explain what you experienced. The OS-01 peptide works as a senomorphic — meaning it helps reduce the harmful effects of aging ("senescent") cells and prevents healthy cells from progressing into that dysfunctional state, rather than reversing or "waking up" follicles that have already gone fully dormant. In other words, it's designed to support and slow the aging of the follicle environment, rather than reactivate follicles that are no longer active. Follicle activity and growth potential naturally vary a great deal from person to person, and factors like age, follicle dormancy, and overall hair biology all play a role in whether — and how visibly — results show up.

    Our clinical research on OS-01 HAIR focused on participants with thinning hair but still-active, healthy scalps, tested alongside daily dermarolling over a 6-month period. Because of that, results at more advanced ages or with longer-dormant follicles weren't the primary focus of that research — which is part of why individual outcomes can vary so much from person to person.

    Your experience matters to us, and feedback like yours helps us understand how our products are working for different people and their individual needs. We're genuinely grateful that you took the time to share this insight with us. Your honesty is valuable, and we appreciate you giving OS-01 HAIR a fair shot.

    Thank you for being a OneSkin customer, Joe.

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Frequently Asked Questions

Can I use this serum alongside minoxidil or other hair treatments and products?

OS-01 HAIR SCALP SERUM complements other medical-grade treatments and can be used alongside other products as well. We always recommend applying OS-01 HAIR first and patch-testing when using other products to ensure the combination of all products works well for you.

 

If you are currently using a product containing Minoxidil please DO NOT completely stop use of that product or treatment. We recommend using OS-01 HAIR SCALP SERUM in combination with the product containing Minoxidil. You can start using OS-01 HAIR SCALP SERUM immediately, but do not stop Minoxidil abruptly. If you plan to discontinue Minoxidil, we recommend tapering off gradually over a few weeks or months to minimize excessive shedding. Please contact your physician for individual recommendations on how to safely discontinue the use of Minoxidil.

Can I use this serum if I have sensitive skin or a sensitive scalp?

Absolutely. OS-01 HAIR SCALP SERUM was formulated without known irritants and is clinically validated to be suitable for sensitive skin and scalps.

Is this serum suitable for all hair types?

Definitely! OS-01 HAIR is suitable for all hair types, including oily hair, and integrates easily into any hair care routine with visible results within as little as 90 days.

Is this safe for use during pregnancy or breastfeeding?

All OneSkin products are free of sulfates, parabens, and phthalates. Additionally, we post the full ingredient list of each product on the description pages. We recommend consulting with your doctor if you have any concerns about starting new products while pregnant or breastfeeding, as they know your particular needs best. As always, we recommend pregnant and breastfeeding women consult their physician with any questions or concerns.

Do I apply this before washing my hair or can I leave it on?

OS-01 HAIR SCALP SERUM should be left on and not rinsed. Apply 1mL of OS-01 HAIR SCALP SERUM 1-2x daily (AM or PM) directly to your entire scalp and massage in with your fingertips. Leave on, and do not rinse. For enhanced absorption, use a dermaroller on a clean scalp before application.

Citations

  1. Based on a 6-month, double-blind, third-party clinical study with 32 participants (23F, 9M), ages 27–55, using OS-01 HAIR SCALP SERUM twice daily and dermarolling once daily. Hair parameters measured using HairMetrix® clinical photography, Trichoscopy, and Phototrichogram.
  2. Visible biological age defined as signs of aging such as smoothness and barrier strength. Based on a double-blind, third-party 12-week clinical study with 22 participants aged 54–65. (Zonari, A., et al. Journal of Cosmetic Dermatology, 2024.)