OneSkin Hair Serum Review: Before and After
A New Option for Hair Restoration?
As we set out to complete our review of OneSkin’s OS-01 Hair Serum, we knew we were building upon the science they’d already been very successful in taking to market.
We have thoroughly profiled the core technology behind OneSkin - namely the OS-01 peptide. This peptide has been powerfully demonstrated to activate the repair mechanisms in skin which eliminate senescent cells in the skin
It seems pretty clear that there then might be a follow-on application for hair loss, given that there is now an emerging and clear connection between these cells and hair loss. While the science is still being settled on exactly how and to what extent cellular senescence impacts hair growth, here is what we know so far:
The cells which drive hair growth and or the surrounding skin can become sensescent
When they do, the hair follicle loses its ability to regenerate
Progressively, hair becomes thinner, less dense as a result
In particular it results in few hair follicles entering their ‘androgen’ or ‘growth phase’ of the hair growth cycle
Thereby, cellular senescence is one of the drivers of hair loss
OneSkin’s Co-Founder and Chief Science Officer Alessandra Zonari, in an interview with A Longer Life in April 2025 had this to say:
“We started by culturing hair follicle cells and then exposing them to stress hormones to see if they would become senescent. From there, we tested whether our OS-01 peptide could reduce the formation and accumulation of these senescent cells.
And the results were promising. We observed a 20% reduction in the formation of senescent cells, and more than a 30% decrease in the release of inflammatory cytokines. These findings were really exciting and gave us the confidence to begin developing a formulation that could deliver the OS-01 peptide directly to the scalp to evaluate its impact on hair growth.”
OneSkin Hair Serum: Before and After Review
Does OneSkin’s Hair Serum (OS-01 Hair) really work in the real-world, outside of the laboratory? Of course the most important question is - will it work for you? Is it safe for sensitive skin? My ambition with this review article is to demonstrate how you can answer this very question.
As with all longevity technologies, they offer great promise, but often with only very preliminary scientific evidence to support their efficacy.
OneSkin’s OS-01 Hair Serum falls perfectly into this category. While there is a strong argument for the involvement of senescent cells in hair loss, as outlined in our 1:1 interview with CSO Alessandra Zonari - the evidence that this particular product is quite early stage.
As recently as April 2025, the company published results from 6 months of testing on a relatively small cohort of test individuals (30 people), produced through a third-party research organization.
Results are promising and include:
“At baseline, 3 months, and 6 months, participants were measured for hair growth with instrumental analysis HairMetrix® clinical photography, Trichoscopy, and Phototrichogram with analysis to evaluate:
Density (hair count per cm2 & inter-follicular mean distance)
Thickness (sum of hair width per cm2 & average hair width (thickness))
Count of anagen (growth phase) hairs”
Source: https://oneskin.pxf.io/xLXPxA
Overall, they observed:
86% of participants had an average improvement of +39% in hair count
70% of participants had an average improvement of +10 in hair density
73% of participants had an average improvement of 42% in anagen phase hairs (hairs actively growing)
So naturally, I set out to replicate this study on myself, taking particular interest in the results in men, which saw a full 100% of participants experience improvement in hair thickness. Is it ‘hair growth cycle’ or hair growth hype?
Let’s take a look at what I did, and how you can repeat a similar self-experiment at home.
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For my self-experiment with OneSkin, I applied the OS-01 Hair Serum in both the morning and evening.
Prior to application, I used the provided dermaroller, which assists in the absorption of the serum into the deeper skin surrounding your hair follicles (which are located relatively deep within your skin). You should use it according to the instructions, rolling 3-4x times in each of the four different directions (up, down, left, right).
When done correctly with the right amount of pressure, there should be some visible reddening of the skin, indicating that you’ve made the small perforations in the skin required for absorption.
Massage the product into the scalp, taking care to work it into the boundary of your hairline with your forehead. The more of the product you can get onto the scalp in the areas you are targeting, the more chance you have of seeing successful results. I found that brushing my hair back and holding it in place with a headband was very helpful.
At the time of this review, I have used the product for a total of 11 weeks (which are calling ‘3 months’).
How I Gathered Before and After Images for OneSkin Hair
Taking directly comparable photos of your hair line with your smartphone is actually quite tricky. But doing it correctly can provide you with the data you need to track your results.
When you consider that your head is roughly the shape of a sphere, throw in the many different angles of the camera you are using - the combination of possible images you could take becomes mind-boggingly large. My first suggestion to you is that you do not try to take these photos yourself - get some assistance, particularly with the ‘after’ photos.
Keep the ‘before’ images you want to match readily available, preferably on a secondary devices such as a tablet, laptop or second smartphone. This will enable you to match the two photos as best you can.
Use natural lighting, keeping track of the time of day and relative sun exposure. Use the same location if possible, and always avoid using the flash option on your camera.
Unfortunately on my end, this wasn’t all possible. I work from home and had recently moved house - making the ‘after’ photos difficult to match. However, I was able (with a lot of patience) produce comparable photos, which were revealing.
OneSkin Hair Before and After Images (3 Months)
I was able to successfully match two before and after images for each side of my hair line. In this review, I target the corner of my hair line on both sides, where I have experienced the early stages of thinning over the past decade.
In this analysis, we are looking to see if we can identify:
New hair growth (shorter hairs that have entered their androgen phase of the hair growth cycle after being dormant)
Improved hair density
Any improvement in hair thickness
Left Side
As previously mentioned, we aren’t exactly apples to apples here with the photography, but that doesn’t mean we can’t look for the evidence with a trained eye.
What I observe here is evidence of some new hair growth (androgen phase), demonstrated by the shorter hairs emerging in the call-out region (in the circle). I believe there is also some apparent thickening of the hair just behind the hairline (in the rectangle). Microscopic imagery will be used to confirm.
Let’s take a look at another angle…
Here there appears to be greater density of hairs along the initial front of the hairline, where there has been notable thinning prior to using OS-01 Hair. Along the ‘peak’ of the hairline (rectangle), hair density also appears visibly improved.
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Right Side
After thorough analysis, I have been unable to note any significant changes or new hairs on the right side of my hairline at 3 months. It is perhaps noticeable that there was no further hair loss over this period, as remaining at baseline could still be indicative of OS-01 Hair being supportive for hair loss prevention.
Reviewing OneSkin Hair Serum with Dermascope Images
In the data provided by OneSkin, high resolution imagery of the hair follicles was used to calculate hair density through counting the active number of follicles in a given region.
While this not possible to direclty replicate from home without specialized equipment, I decided to gather microscopic images of the follicles with a dermascope. Dermascopes are used in by dermatologists to investigate skin lesions, and provide very clear, quality images of the skin.
Used correctly, we can also use such images to get up close and personal with our hair follicles. The unit I purchased is the Dermlite DL1 Basic (costs around $250USD). It may even shed some insights onto the scalp microbiome. Let’s take a look at what I was able to observe the following.
Left Side
At the microscopic level on the left side, there are several new ‘androgen’ phase hairs visible, which I have highlighted with arrows to help draw your eye to them. The lighting between shots was slightly different, making it challenging to determine here if there was any improvement to hair thickness at this stage. We’ll check back again at 6 months.
Right Side
On the right side, the microscopic images seem to show thicker and darker hair after three months use, with a possible slight improvement in density with at least one new hair entering androgen phase of the hair growth cycle (see arrow) and some hairs that were thin / weak looking much healthier (circle). I wasn’t able to spot much of a signal in terms of scalp microbiome at this stage.
Conclusion: OneSkin Hair Serum - Too Soon to Tell
At this stage, I cannot definitively say that there has been significant improvement to my hair health after 3 months of it being treated with OS-01. This is however, not particularly notable, given that the real benefits of OS-01 Hair Serum only showed up in the independent study after being treated with OS-01 for 6 months (continual use).
As we discussed in our 1:1 interview with Dr. Zonari, hair growth is cyclical and takes some time and patience to note changes in features like density, thickness and new hair growth:
“We generally start to see noticeable improvements around the 3-month mark such as less hair shedding, thicker strands, and more visible growth. One of the first things people notice is a reduction in shedding, followed by hair that feels stronger and a scalp that feels healthier less itchy, less irritated, especially for those who struggle with sensitivity in that area.
We also conducted beta testing and gathered data at 1, 2, and 3-month intervals. While results varied, we started to see strong improvements after just 2 months in many cases. But again, the key is regular, consistent use, especially in the beginning.”
My verdict is at this stage, inconclusive at the n=1 level (meaning results just for me). I will continue to use OS-01 Hair twice per day over the next three months and will update this post with 6 months results. Who knows what may happen after my scalp has been treated with OS-01 for six months! I’ve seen it transform my face before!
Be sure to subscribe to the ALL-in weekly newsletter, so we can keep you informed about all of our latest content - including when I update this post with my 6 months results.
In the meantime, if hair loss is a concern for you, perhaps you could join in with us and self-experiment with OS-01 Hair! We’d love to share your before and after results with our audience in the spirit of community - just drop us an email!
One Skin Hair Serum: Frequently Asked Questions (FAQ)
Top FAQs About OneSkin OS-01 HAIR Serum
What is OS-01 HAIR, and how does it work?
OS-01 HAIR is a peptide-based scalp serum designed to combat age-related hair thinning by targeting cellular senescence often referred to as "zombie cells." By reducing these dysfunctional cells, the serum aims to rejuvenate the scalp microbiome / environment, promoting healthier hair growth.How should I apply OS-01 HAIR, and how much should I use?
Apply 1mL of OS-01 HAIR serum directly to your scalp once or twice daily (morning or evening). Use the dropper to measure the amount, and massage the serum into your scalp with your fingertips. For enhanced absorption, consider using a dermaroller on a clean scalp before applicationIs OS-01 HAIR suitable for all hair types?
Yes, OS-01 HAIR is formulated to be compatible with all hair types, including oily hair. It integrates seamlessly into various hair care routines and is designed to deliver visible results within approximately 90 days.Can I use OS-01 HAIR alongside other hair treatments or on color-treated hair?
Absolutely. OS-01 HAIR is safe to use with other hair products and treatments, including those for color-treated hair. It's also suitable for individuals with sensitive scalps or conditions like dandruff and psoriasis.What are the key ingredients in OS-01 HAIR besides the OS-01 peptide?
In addition to the proprietary OS-01 peptide, the serum contains:Panax Ginseng Root Extract: Believed to stimulate blood flow and improve circulation to the scalp.
Glycerin: A humectant that retains moisture.
Panthenol: A conditioning agent.
Inulin: Acts as a prebiotic, potentially supporting a balanced scalp environment.
Helianthus Annuus (Sunflower) Sprout Extract: Provides antioxidant properties.
Morus Nigra (Black Mulberry) Leaf Extract: A conditioning agent.
Rehmannia Chinensis Root Extract: Assists with conditioning effects.
Niacinamide: A skin conditioning agent.
Are there any side effects associated with OS-01 HAIR?
While OS-01 HAIR is generally well-tolerated, some users may experience mild scalp irritation or sensitivity. It's recommended to perform a patch test before full application, especially if you have sensitive skin or known allergies.How long does it take to see results with OS-01 HAIR?
Clinical studies have shown that users may experience significant improvements in hair thickness and density after 3 to 6 months of consistent use.
One Skin Hair Serum: Scientific References
Senotherapeutic peptide treatment reduces biological age and senescence burden in human skin models
Restoration of hair follicle inductive properties by depletion of senescent cells
Age-related hair changes in men: Mechanisms and management of alopecia and graying
Dysfunction of Hair Follicle Mesenchymal Progenitors Contributes to Age-Associated Hair Loss
Cellular senescence: ageing and androgenetic alopecia
Premature Senescence of Balding Dermal Papilla Cells In Vitro Is Associated with p16INK4a Expression
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