Microneedling for Hair Loss: A Recent Literature Review Reveals Exciting Results

In this video, Rob from Perfect Hair Health discusses a recent peer-reviewed study on microneedling for hair loss. The study is a comprehensive literature review that examines the effectiveness and safety of microneedling as a treatment for hair growth. Rob highlights that microneedling, which involves creating tiny wounds on the scalp with medical-grade needles, can stimulate inflammatory reactions that trigger growth factors and signaling proteins essential for wound repair. He discusses the positive signals and accumulating evidence from animal studies that suggest microneedling can have a positive effect on hair follicle proliferation, reducing fibrosis, and improving the wnt signaling pathway. The study also delves into the best practices for microneedling, including needle length, session frequencies, and device selection. Rob cautions that while the data is encouraging, it is important to note that the quality of the studies is low, and more research is needed to draw concrete conclusions. Nonetheless, microneedling shows promise as a standalone therapy and as an adjunct treatment for hair loss.

Author Icon

Our Summaries are written by our own AI Infrastructure, to save you time on your Health Journey!

How does this happen?

Key Insights:

  • Microneedling is a buzz word for percutaneous wound induction, which involves using medical-grade needles to create an inflammatory reaction on the skin.
  • Microneedling has been shown to improve the appearance of wrinkles, partially reverse acne scars, and improve pigmentation disorders.
  • Research has suggested that microneedling may have positive effects on hair follicle proliferation, including reductions in fibrosis and improvements in stem cell proliferation.
  • Microneedling has been found to be effective for both men and women with androgenic alopecia (pattern hair loss).
  • Studies have shown that microneedling can be effective as a standalone therapy or when combined with other treatments such as platelet-rich plasma (PRP), minoxidil, or oral medications.
  • The data on microneedling for hair loss is limited and of lower quality, making it difficult to draw definitive conclusions.
  • The best microneedling length and frequency for hair growth are still under research. However, depths of 0.6-0.8mm and frequencies of once every 7-14 days seem promising.


My team and I just published a new peer-reviewed study on microneedling for hair loss. It’s a literature review, and right now, this is perhaps the most up-to-date resource in the world on this topic, which is why I’m so thrilled to share the information with everybody. So that anybody watching this video can turn everything that we’ve compiled in this paper into actionable insights, hopefully take their hair growth to a new level. We’re also going to use this paper to address six key questions that I know that people have been dying to know the answers to. So if you’re considering adding microneedling to your hair loss routine, or if you’ve already been doing it for a while and you might be worried that you’re doing it wrong, this video is here to help.

This is Rob from Perfect Hair Health, and today I am excited to say that our latest peer-reviewed paper has officially been published. A literature review on microneedling: do these medieval torture devices actually improve haircuts? We’ll find out in this video because despite the popularity of these little tools, there’s still a lot that we don’t know about their viability for hair growth or their long-term safety. We really need to be careful about using them, which is why we’re creating this video.

But before we get into any of that, you might be wondering, what is microneedling? And why would anybody ever think that jabbing needles directly into our heads might stimulate hair growth? Microneedling is essentially just a buzzword for percutaneous wound induction, which is a fancy way of saying that you take medical-grade needles, often times one to five millimeters, and you jab them into your skin to create an inflammatory reaction.

While that sounds masochistic, and honestly, it is, acute inflammation is actually a part of everyday living, and without it, we couldn’t even exist. Inflammatory substances, free radicals, reactive oxygen species, they do do damage, but they also double as signaling molecules for our cells. They’re actually necessary for fundamental functions of our biology. I mean, if we somehow found a way to push a mute button on all inflammation in our body, people don’t know this, but our cells would actually lose key pathways of communication, and in about 40 seconds, we’d literally be dead. So we cannot demonize all inflammation. Too much can absolutely be a problem, it can absolutely cause scarring, but a little bit, it’s actually good. Which begs the question, can we actually use lower levels of inflammation to our advantage? Well, yeah, and it’s this very principle behind microneedling.

These devices were first described by Orrin Tawny back in the 1990s, and yes, that is the same Orrin Tawny who published the first-ever hair transplant study on humans with androgenic alopecia. Anyway, Orrin Tawny first identified an opportunity to use these tiny little torture devices to induce micro-wounds, the type that wouldn’t cut deep enough to necessarily cause scarring, but would cut deep enough to evoke a reaction from the body. We’re talking growth factors, signaling proteins, all the stuff that our body typically utilizes in wound repair. And he hypothesized that repeated micro-wounding in skin that might be already damaged, we’re talking things like scars or wrinkles from aging or maybe even skin with pigmentation disorders, things like vitiligo. Well, that the wounds from microneedling, they might actually help to induce new collagen, create new blood vessels, and maybe over time, restore the functionality and the integrity of the tissue.

Fast forward about 30 years later, and we now know that these little devices, when used correctly, can essentially improve the appearance of wrinkles, partially reverse scars from acne, improve pigmentation disorders, and so it is no wonder that interest in microneedling has recently exploded. But how do we make the leap from skin health to hair health? Well, no brainer here, hair grows out of skin, and the health of our skin and our hair are closely intertwined. And in the last 20 years, researchers, as they’ve accumulated evidence on microneedling, they’ve also seen a lot of positive signals, mostly from animal studies, that microneedling might have an effect on the things that we actually care about for hair, follicle proliferation. We’re talking about reductions to fibrosis, the enhancement of drug delivery, the normalization of things like the Wnt signaling pathway, improvements to stem cell proliferation, dermal papillary cells. If you want to better understand why these things are important for our hair health, check out our other studies that we’ve published, read the articles on our site, watch our other videos on this channel. We’re not going to get into every little detail here.

Anyway, these little signals from research, they started to accumulate, and they started to get researchers interested in asking, can we use these little torture devices on our scalps to actually induce new hair growth? And initially, the first few times this was tried, the answer seemed to be yes. I mean, we all remember that 2013 study from Rassman’s team that applied 5% minoxidil in one group and 5% minoxidil plus once-weekly microneedling in the other group, and the results were fantastic. We’re talking about 400% relative increases in hair counts for the group using microneedling plus minoxidil versus the group who just used minoxidil by itself. Again, that is a relative increase, not an absolute increase. Otherwise, the patients at week 12 of the study probably would have looked like Chia Pets. But this landmark study really kick-started interest in microneedling in the hair loss community. And with more clinical trials across different devices, different needling lengths, different session frequencies, the hope was that over time, we’d unlock new levels of hair regrowth. We’d learn best practices, we’d figure out what works and what doesn’t.

So you fast forward to today, eight years later, nine years later, and we have literally dozens and dozens of studies on microneedling in humans for the treatment of hair loss. And that leaves us with a big question: is microneedling actually an effective treatment? Is it safe? What are the best practices? Does it work as a standalone treatment? Does it pair well with other treatments? Well, these are questions that we set out to answer in our systematic literature review, which was just published in December of 2021. So let’s start answering them.

For those who don’t know, a literature review is essentially a study that systematically searches all publications ever done on a specific topic. In this case, it’s any study published on microneedling for the treatment of hair loss disorders in humans. You work with a team to settle on search terms that you think will capture all of the publications ever done. Then you create inclusion and exclusion criteria for which studies to keep in your analysis and which studies to do away with. For us, that meant excluding studies on animal models, obviously including studies on humans, and doing away with studies that maybe had small sample sizes, were more like case reports or case series, or perhaps they were designed to be done retrospectively. And the reason why we would eliminate those is because they all tend to rank lower on the hierarchy of evidence, they often have a higher risk of bias in their results reporting.

So then you have your team, and yourself, you individually review every single title, abstract, and relevant full texts. You rank each study included by the level of quality and evidence. Then you have to go through a very tedious process of extracting all the relevant data from every study. In this case, that meant reporting the types of hair loss studied, the microneedling devices used, the needling lengths, the session frequencies, the number of sessions, the way the sessions were ended, adverse events, hair loss outcomes, adjuvant or comparator treatments. I mean, the list is massive. And then you have to find a way to organize all this information into a series of tables, which is super annoying. And finally, using all of that extracted data, you go through the process of finding studies with similar enough designs where you can pull subgroups together to run regression analyses, for what we call a meta-analysis. Doing this increases your statistical power, and it starts to tell people, at a very macro level, what trends in the data are showing for this specific intervention. Finally, you have to organize everything, you’ve got to write up all of your results, summarize the key findings, identify limitations across each study, and then you get to start making recommendations for future research teams so that they can design better clinical trials. And that’s why I love doing systematic reviews because when done properly, the insights derived will directly influence the future of research.

So we did all this, and after doing all this work, what did we discover about microneedling for hair loss? And if you’re considering microneedling, what do you need to know right now to start maximizing your results? Let’s start at the very top level. After all was said and done, our literature review included 22 clinical studies. Five of these studies were on patients with autoimmune forms of hair loss, things like alopecia areata and alopecia totalis. We’re actually going to exclude these findings from our video since the data here were really limited. We’ll cover them at a future video at some point. So this really just leaves us with 17 studies, totaling 911 patients, all of whom had androgenic alopecia, also known as pattern hair loss. If you don’t know what pattern hair loss is and you have made it this far into the video, I commend you and I’m also flabbergasted. But it is essentially one of the world’s most common hair loss disorders. It’s chronic, it’s progressive, it often worsens without treatment, and you can’t walk down a city block without spotting somebody with the condition. And it tends to look like this in men and this in women. It’s driven by a combination of male hormones like dihydrotestosterone or DHT, it’s driven by genetics, there are a few other factors involved, and it’s what most people watching this video will be facing.

So let’s start with the good news. Across 17 clinical studies and 911 subjects, microneedling improved outcomes for androgenic alopecia both as a standalone therapy and when combined with other treatments. We’re talking platelet-rich plasma or PRP, minoxidil, growth factor solutions, oral medications like finasteride or spironolactone, you name it. Better yet, in 15 of those studies, investigators used phototrichogram devices and software for hair count measurements. So you could really quantify the changes to hair counts, hair diameters, vellus versus terminal hairs. That is an amazing sign. And while the data are limited, it seemed as though microneedling also worked for both men and women. Finally, across the 536 patients in these studies who did microneedling procedures, no serious adverse events were reported. Of the mild adverse events, they were basically relegated to things like minor discomfort. We’re talking transient pain, a little bit of scalp irritation, or maybe a small headache after the procedure that went away after an hour or so. In fact, withdrawals for those using microneedling devices were virtually the same as for those withdrawing while using minoxidil. So, to reiterate, this all sounds incredible so far. I mean, given all of the information I’ve shared, the great safety profile, the great hair growth outcomes, it might seem like we should all just go out and buy a microneedling device and start jabbing our scalps, right? Well, not so fast. There are some problems with the data. In fact, big problems. And before we go further, we need to discuss them.

The biggest problem is that across all of these microneedling studies, the data is what we would refer to as lower quality. That means that despite things looking encouraging at a far level, when we peel back the curtains, when we dig a little bit deeper, the way that these studies were designed, they actually put the results at a high risk of bias or a risk of misinterpretation. So here are three critical examples that we found in the datasets. First, none of these studies included what we would refer to as an untreated control group. It’s basically when there’s a group of people who receive no treatments at all but they’re still a part of the study. You track their hair counts over time and then you measure the changes to their hair versus the treatment groups. And that gives you a better idea of whether that treatment is actually really having an effect or whether perhaps there’s some external factor that might be influencing hair counts. We’re talking things like seasonality or maybe even the belief that you’re doing something for your hair and that that might be working, which ironically can also increase hair counts. It’s called the placebo effect. I mean, after all, when you look at the data on a drug like finasteride, five-year studies show that in the group taking that drug, most people see amazing hair growth outcomes. What gets lost in that conversation is that when you look at the placebo group, the people taking a sugar pill, 25% of them at year five still have what most investigators would look at and say is the same head of hair. So having an untreated control group is really, really, really important for these reasons. And none of these androgenic alopecia studies for microneedling, seriously, none of them have one. And that’s just problem number one.

Problem number two is that all but one of these studies were of durations that lasted under 52 weeks. Now, our hair counts are influenced by things like sunlight exposure and thereby seasonality. And in the northern hemisphere, we tend to see upticks to hair shedding right around the end of summer. That’s July and August. So that means that depending on when you actually begin the treatments for your study, you can have seasonality working for you or working against you. I even made a video about how a lot of hair loss companies will use the effect of seasonality to their advantage to make it look like treatments such as laser therapies are actually more helpful than they really are. If you want to learn more about that, check out my video on telogen effluvium because it is one of those things with hair loss research that is both disturbing and fascinating. Anyway, this means that for studies running less than a year, we really can’t control for seasonality because we aren’t able to bring back that hair cycle to where it initially was when the study started. This is less of a problem when you have an untreated control group, but again, none of the microneedling studies for androgenic alopecia had an untreated control group. So these shorter study durations, they’re a bit problematic. They might be working for the results or against the results. And these factors are partly why when we evaluated the quality rankings of each study in the microneedling research, so many of these investigations had what we call low Jadad scoring. That’s also known as the Oxford scale. It’s a tool used to evaluate study quality. You don’t need to know all of the ins and outs here. All you need to know is that it’s five points higher is usually better, and three is nothing to write home about.

The third problem is a fancy term known as heterogeneity. That is just a way to say that the data across every single study were mostly incomparable because the study designs, well, they were so all over the place. We’ve got studies on microneedling testing needling lengths of 0.25 millimeters. We’ve got others testing 2.5 millimeters. That’s 10x the needle length. We’ve got studies doing microneedling alone and studies doing microneedling plus growth factors or minoxidil or finasteride or spironolactone. We’ve got studies that test microneedling once weekly, others doing it once monthly, others using a titration schedule. We’ve got different session endpoints. Some are described as more gentle, such as erythema. Others sound a lot more violent, pinpoint bleeding, hemorrhage. Some session endpoints are built around set time limits, others don’t have that. We’ve got different patient populations, different adjuvant treatments. I mean, the chaos in the tables that we had to create is something to behold. And because of just how differently each study was conducted, unfortunately, we had to decide against running a meta-analysis. Again, that is where you pool data across studies to better understand microneedling’s effects. But we looked at this data, we ran it by multiple biostatisticians, and most agreed, as did we, that these study designs were mostly incomparable to one another. It wasn’t a problem with the endpoint assessments. It was a problem with the methodologies for microneedling itself, the interventions, the comparators, the methodologies, the way that devices were used. Basically, we couldn’t pool the data, and if we did, we would have risked drawing false conclusions. We’ll actually revisit this topic later in the video because another research group, they decided to do an analysis here, and we need to talk about it because I have a few concerns.

But nonetheless, these are just a few of the problems that we saw in the datasets. There are others, and if you want to learn about them, you can check out the links below. We’ve provided the study, it’s open access, nobody has to pay a thing to read the materials.

Okay, now that those disclaimers are out of the way, let’s talk about some of the big takeaways from our read of the data on microneedling, the stuff that people actually care about, like what is the best microneedling length, does microneedling work by itself, can we substitute microneedling for other hair loss treatments and vice versa? We’re going to cover all of these, but just know that what I’m saying is subject to change as more studies are published. But if you’re looking to take your hair growth to another level based on the data that we do have available, here are the trends that we’re seeing that currently excite us about the data.

First, in a split scalp study comparing microneedling to platelet-rich plasma therapy or PRP, microneedling was actually found to be just as effective at regrowing hair versus PRP. This isn’t too surprising because, after all, both microneedling and PRP, they stimulate wound healing pathways. What is surprising is the cost differential. Microneedling rollers cost $10 to $20, while a PRP session in the US costs something like $1,200, and it needs to be repeated several times per year to remain effective. Now, the study that we just referred to, it’s not perfect. We’ll get more into that in point number two. But these findings do align with what I’ve noticed for a very long time, which is that PRP is overpriced for what it actually delivers to hair loss patients. In fact, I recently had a conversation about this with one of the world’s leading hair loss surgeons, Dr. William Rassman, where he revealed data from a conference that he attended that discussed biases in the clinical trials published on PRP. That full hour interview is not on YouTube, but you can watch it in its entirety inside of our membership community.

Point number two, microneedling by itself seems to improve hair counts. In our analysis of the data, we found six studies on androgenic alopecia that featured subjects using microneedling as a standalone therapy. Two of these subgroups within these studies saw significant increases to total or terminal hair counts. One of them saw significant increases to both hair diameters and total hair density. And three groups noted no statistical effects. Another research group, which wasn’t us, recently decided to pool these subgroups together, run a regression analysis, and they actually came to the conclusion that microneedling by itself might even be more effective than 5% minoxidil as a monotherapy. But again, we have to be super careful about how we interpret these data because, in my eyes, these subgroups, well, they’re mostly incomparable. Just take a look at these studies pooled together for the analysis. One of the subgroups featured subjects using this weird stamper thingy at home twice weekly at a 0.25 millimeter needle length. That subgroup saw no effect. The other subgroups used automated pens administered by physicians in clinic one to four times per month at 1.5 to 2.5 millimeter needle lengths. Those groups often did see an effect on hair. And then, across all subgroups, the session endpoints were not the same. Some ended a microneedling session based on the set number of passes or minutes, others ended a session based on their scalp turning pink or a little bit red and inflamed, others ended a session based off of pinpoint bleeding. And then, it gets even more complicated than that because two of the studies in this analysis, well, they also featured split scalp study designs. That’s where you do half treatments on one side of the scalp, half treatments on the other side of the scalp. One of these tested microneedling versus microneedling plus PRP, the other tested microneedling versus microneedling plus growth factors. The problem is, in split scalp designs, there’s a possibility of treatment diffusion across scalp zones, which might muddy the results of interpretation, especially when you’re doing injectable things like intradermal injections. Now, I say this, knowing full well that the PRP studies showed benefits to both sides of the scalp, whereas the growth factor study only showed benefits to the growth factor side of the scalp. So who knows what’s really going on? But the bottom line is that pooling these subgroups together are, in my eyes, a bit dangerous, a bit disingenuous. While all of these studies used similar hair counting methods, the methods by which patients received microneedling procedures, they were often wildly different. So it’s sort of like grouping together apples and oranges. And that’s why I’m just a little cautious about taking these data as gospel. Nonetheless, I personally feel that microneedling by itself does work for hair count improvements. Because when you look at the best controlled studies in this analysis, I’m talking about the ones without split scalp designs and the ones with specific session endpoints, well, those ones you get consistent findings, a response rate of around 70 to 80 percent, and about a 15 percent increase in terminal hair counts over a three to six month window. In many cases, that confers to a cosmetic improvement. I see that as very encouraging. So I think that these pathways deserve further exploration, even as a standalone therapy.

Point number three, microneedling appears to enhance the effectiveness of nearly every other treatment, PRP, oral medications like finasteride or spironolactone, and especially minoxidil. This is true for people who are just starting treatments and for those who have used hair loss drugs for a long time, maybe they’ve plateaued in their hair growth and who want to add an extra kick to their regimen. It seems like microneedling can stimulate that extra kill. Regarding minoxidil in particular, microneedling seems to do three interesting things. First, its use enhances transdermal absorption of the drug through wounding. Second, the wounds themselves increase the activity of sulfotransferase, that’s the enzyme that minoxidil has to come into contact with in the scalp in order to activate and then have an effect on our hair follicles. That means that microneedling increases the activation of minoxidil. And third, microneedling appears to amplify minoxidil’s effects on the Wnt signaling pathway. That is actually a really big deal because the Wnt pathway, at least currently, is one of the key pathways that we believe regulates hair growth. And it’s also the pathway that hormones like DHT dysregulate. That means that microneedling plus minoxidil might actually augment these pathways even in the absence of using a DHT-reducing drug. That is very exciting in my eyes, especially for people who cannot tolerate finasteride or who don’t want to use it because perhaps it doesn’t fit with their treatment preferences.

Point number four, microneedling might also enhance the staying power of drugs like minoxidil. In other words, if you use minoxidil in combination with microneedling and then you withdraw from both treatments, subgroup analyses in one of these studies suggested that your hair gains will stick around for much longer than if you were to only use minoxidil, then quit. We actually found this very interesting. We made a video about it recently, so check out that video for more information. For now, keep in mind that this is a tiny subgroup analysis, so don’t get too excited, don’t do something crazy like withdraw from all treatments just because I happen to mention this.

Fifth, it might not matter much what device you actually use for microneedling, we’re talking about derma rollers or stamps or automated pens. Rather, what might matter most is the depth of needle penetration and the number of passes. This is really interesting because for people who cannot afford automated pens and who are maybe relegated to using manual rollers, well, you might not actually be leaving any hair regrowth on the table. So let’s dive into this a little bit more because I think the data here are fascinating. First, there aren’t many studies comparing varying needle lengths or devices for microneedling in the use of hair loss disorders, so big disclaimer there. However, one of the studies that we do have found with an automated pen and the use of 5% minoxidil that a 0.6 millimeter needle length outperformed a 1.2 millimeter needle length. The difference was statistically significant, but when you look at the actual data, it wasn’t really biologically significant, as in we’re not talking about big differences in hair counts here. Nonetheless, the investigators suggested that maybe the better effect from the 0.6 millimeter needle length had something to do with where the hair bulge sits, specifically this reservoir for stem cells that resides roughly 1 to 1.8 millimeters deep in our scalp skin surface. So puncturing right above the hair bulge will still recruit these stem cells through the healing process, but without actually damaging the bulge itself, whereas needling depths that are greater than one millimeter, well, they’ll probably hit the bulge, still recruit the stem cells, but perhaps hitting the bulge, maybe it’s not what we want, maybe it isn’t necessary, maybe it weakens results somehow. Again, we are talking about very minor differences here in hair outcomes, and you need to keep this in mind. And you also need to keep in mind that other studies showed that needling lengths all the way up to 2.5 millimeters achieved great hair growth outcomes. So if you’re using a longer needle length and now you’re worried that you might be doing damage, don’t worry about this, you’re probably fine. But the big point here is that the data seem to be converging around a needle depth penetration of between 0.6 and 0.8 millimeters. You actually can achieve that depth with an automated pen set to 0.6 to 0.8 millimeters or a manual roller with a needle length of 1 to 1.5 millimeters. So why the difference? Well, because rollers are subject to things like user pressure variability and the angulation of entry for each needle. So that means when you’re using a roller, the needles actually don’t penetrate as deep as their lengths are set. The best estimates that we have on this say that they only go about 50 to 75% as deep. So based on that data, wounding depths of 0.6 to 0.8 millimeters seem best, and you can achieve that with automated pens set to the same length or with microneedling rollers that are set to 1 to 1.5 millimeters. For stamps, we have literally no data, but I guess it boils down to just how hard you want to push down.

Point number six, so far, the best needling frequencies, they seem to be hovering around once every seven to 14 days. And that’s not to say that shorter frequencies aren’t better, they very well might be. After all, we’ve seen some real diehards on hair loss forums using things like a 1.5 millimeter needle length daily and then sharing amazing results of their hair regrowth. So let’s not confuse the absence of evidence as evidence against something. But going off the clinical data, which predominantly consists of needling frequencies of once weekly or greater, it seems like the best intervals for safety and efficacy are settling on once every seven to 14 days.

Alright, those are the six takeaways that we wanted to share with everyone, but there are literally dozens more. So if you’d like to learn about all of the takeaways from our literature review, you can give the entire study a read by clicking the link below. Again, just as with all the papers that we publish, they’re open access, which means that nobody has to face a paywall to access the information. And if you’re looking for a demonstration video on how to microneedle, that’s not included in this video, but we do have one of those. It’s a detailed video guide, it’s a how-to guide, it walks you through exactly what to do, and it’s available to those inside our membership community. And remember, as one of my favorite researchers, Jeff Donovan, once said, research on microneedling is still in the infancy stage. It hasn’t made it to preschool yet. There’s still a lot that we don’t know, including the best practices. So these results, they are subject to change. But we’re doing the best we can with the data that we currently have. Regardless, feel free to subscribe to the channel for more videos, more study analyses, and more deep dives into a range of hair loss topics from causes to treatments.

On a personal note, I actually think of microneedling as just a stepping stone to more effective wound healing therapies for hair regrowth. We’re actually trying to set up a trial for what I would consider the next evolution of wounding-based therapies for those with androgenic alopecia. Depending on where the project goes, I look forward to sharing more details in future videos. For now, take care, and we’ll see you next week.