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The Rosemary Oil, Minoxidil, Hair Loss “Breakthrough” Study
In 2015, a team of Iranian researchers made headlines after publishing a study on rosemary oil, minoxidil, and hair loss.
The team wanted to compare the effects of rosemary oil versus 2% minoxidil on hair count. So they conducted a test on 100 men with pattern hair loss (androgenic alopecia). Fifty applied rosemary oil; fifty applied 2% minoxidil.
Their findings? After six months of twice-daily application, rosemary oil significantly increased scalp hair count… and just as much as 2% minoxidil (the active ingredient used in Rogaine).
The implication: rosemary oil might be an effective hair loss treatment. Better yet, it might be just as effective as Rogaine – an FDA-approved hair loss drug.
The study made its waves in hair loss forums. Some users claimed the “natural” alternative to Rogaine had finally arrived. Others offered to dump their Rogaine and instead switch to rosemary oil. A few even opted to self-test rosemary oil and track their hair regrowth progress throughout the year.
Fast-forward three years later: is rosemary oil still considered an effective “natural” hair loss treatment?
The answer isn’t what you’d expect.
In fact, when we dive into the data behind the rosemary oil-minoxidil hair loss study, the results are much more surprising… and even more important (and for an entirely different reason).
By the end of this article, we will uncover…
- What Is Rosemary Oil?
- The MISLEADING Results Of The Rosemary Oil Vs. Rogaine Hair Loss Study
- The Evidence: How Does Rosemary Oil Help Slow, Stop, Or Reverse Hair Loss?
- The Case Study: A Before-After Hair Regrowth Photo Of Rosemary Oil + Another Intervention
- Should We Use Rosemary Oil To Reverse Hair Loss? (And If So, How?)
- Final Thoughts For Anyone Using Rosemary Oil For Thinning Hair
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What Is Rosemary Oil?
Rosemary (rosmarinus officinalis) is a woody plant with fragrant, needle-like leaves and flowers. It belongs to the mint family (lamiaceae) and is native to the Mediterranean region.
While rosemary oil is typically used in perfumes and foods due to its pleasant scent and unique flavor, its benefits also extend to medicine. For decades, cultures around the word have used rosemary oil to treat inflammatory conditions ranging from arthritis to asthma to nerve inflammation. And more recently, studies are demonstrating that rosemary oil may help slow, stop, or even reverse pattern hair loss.
The question is… if we start using rosemary oil, how much hair regrowth can we expect?
Let’s dive back into the rosemary oil-Romaine study to find out.
MISLEADING Results: What Everyone Missed About The Rosemary Oil Vs. Minoxidil Hair Loss Study
At a first glance, the rosemary oil study looks promising.
For one, the study was conducted on humans – not rats. Human hair growth studies are harder to come by. And if there’s one thing I’ve learned during my ten years of hair loss research, it’s that everything regrows hair on rats – but rarely do those results carry over to humans.
Secondly, the study was done for a realistic length of time – six months. Many human hair loss studies last just three months – barely enough time to gauge a measurable effect on hair growth.
Thirdly, the study’s abstract reveals that rosemary oil not only increased hair count… but it was also just as effective at increasing hair count as 2% minoxidil. That’s huge news! Especially for hair loss sufferers worried about the side effects of Rogaine or who prefer to seek a more natural treatment route.
But there’s one big omission in the study’s abstract: for the rosemary oil and minoxidil groups, how much did hair count increase after six months?
The numbers will surprise you.
Rosemary Oil Versus Rogaine: An Increase In Hair Count… But By How Much?
I dug into the study to find answers (the study starts at page sixteen).
To gauge hair count, researchers took before-after treatment photos and used two dermatologists to independently count specific segments of each participant’s scalp.
The results? An increase in hair count in both groups. But by how much? See this chart within the study:
Having trouble eyeing the difference in hair count between baseline and six months for each group? Me too. So I checked the actual numbers. Here’s the summary:
After six months, the rosemary oil subjects saw a 5.5% increase in hair count. And the minoxidil group? Just a 1.7% increase. And when I saw the standard deviations, I couldn’t believe those hair count differences were actually statistically significant.
This brings up an important question.
Is This Hair Count Increase Due To Rosemary Oil, Minoxidil… Or Seasonality?
Hair count changes at that magnitude (less than 10%) might not even be attributable to either topical. In fact, they might just be attributable to a natural phenomenon called seasonality.
Depending on the season, hair cycles can increase (or decrease) our total hair count and density by as much as 10%. Anyone who owns a dog knows how much they shed during certain parts of the summer and winter. Believe it or not, humans also undergo a similar (but less drastic) effect.
Unfortunately, there was no control group in this study, so we don’t know much of that hair count increase we can attribute to normal seasonality… and how much we should truly attribute to the rosemary oil or 2% minoxidil.
And what about photo evidence? Researchers highlighted one before-after photo for each group. Neither photo was very impressive. Here’s a before-after of one rosemary oil subject:
Now that we see the photos and actual hair counts, what’s this study’s key takeaway?
The major finding probably isn’t that rosemary oil increases hair count by 5.7% in six months – or that it boasts a similar effect to Rogaine.
The real takeaway is actually that 2% minoxidil – an FDA-approved hair loss drug for women – is just not very effective for men.
An Alternative Interpretation Of The Rosemary Oil-Minoxidil Study: 2% Minoxidil Isn’t A Very Effective Hair Loss Treatment (For Men)
The second problem with this study is that the study authors compared rosemary oil to 2% minoxidil. However, 2% minoxidil is the formulation used to treat female pattern hair loss, whereas 5% minoxidil is what men use for the same condition.
This is problematic for a variety of reasons – one of which is that studies show 2% minoxidil is far inferior to 5% minoxidil in men. That means the study doesn’t necessarily give us a fair comparison of rosemary vs. minoxidil in real-world usage settings for this cohort of people.
This study highlights why it’s important to look beyond a study’s abstract – especially when it comes to hair loss. While the summary may make a study’s results look enticing, the reality is that if an abstract is void of numbers, there’s probably a good reason.
Now back to rosemary oil. Should we even bother? Well, a 5.5% increase in hair count is modest… but appreciable. And all seasonality aside, there’s a good chance both test groups would’ve lost hair over the same period had they not sought either treatment.
So, should we include rosemary oil into our natural hair regrowth regimen?
Maybe. In fact, there’s some mechanistic evidence that rosemary oil (when combined with another hair loss treatment) may become additionally more effective at recovering lost hair.
But first, it’s critical that we understand the science behind rosemary oil – how it promotes hair regrowth, why, and how we can use these mechanisms of action to our advantage. The evidence points to five key mechanisms in which rosemary oil encourages hair regrowth – and we’re going to cover all of them.
The Evidence: How Rosemary Oil May Help Fight Pattern Hair Loss
Let’s start by breaking down the components of rosemary oil.
Rosemary plants contain a volatile oil which can be extracted using a process known as steam distillation. This volatile oil (rosemary oil) contains a number of bioactive antioxidants – rosmarinic acid, carnosic acid, ethanolic acid, 1,8-cineole, and camphor (to name only a few). And fortunately for us, these specific compounds within rosemary oil have a variety of pro-hair effects.
In fact, when applied topically, rosemary oil may…
- Reduce inflammation
- Act as an antibacterial agent
- Reduce androgen activity (read: decrease DHT)
- Prevent fibrosis
- Increase blood flow
…all of which will may slow, stop, and partially reverse hair loss.
So let’s take these one-by-one, and then explain how each relates back to thinning hair. Keep in mind the evidence here is built mostly on mechanistic and animal studies. These have translatability problems to humans with androgenic alopecia. So, we should take the rest of this article with a grain of salt.
1. Rosemary Oil Is Anti-Inflammatory
Certain acids in rosemary oil – like rosmarinic and ethanolic acid – have a direct impact on inflammation. In fact, these acids can significantly attenuate (or reduce) the inflammatory process, and in doing so, help fight hair loss.
It all has to do with cytokines and the COX-2 enzyme.
The Cytokine-COX 2-Inflammation Connection
When our tissues get injured, our injured cells begin to release small proteins called cytokines.
Cytokines are signaling proteins. They tell our cells whether to induce or reduce inflammation. After our bodies receive an acute injury (like a cut or a bruise), certain “pro-inflammatory” cytokines arrive to that injury and start telling our tissues to attract more inflammatory cells to the damaged site.
At the same time, our damaged tissues also begin expressing an enzyme called cyclooxygenase 2 (COX-2). COX-2 increases the production of another inflammatory mediator: prostaglandins. (We’ve covered prostaglandins before).
Together, cytokines and the COX-2 enzymes (via prostaglandins) help control how many inflammatory cells actually arrive at an injury site. The larger the injury – the more inflammatory cells our tissues need to heal.
Once these inflammatory cells arrive at the injury, they start releasing enzymes to break down and help “digest” our devitalized tissue. And after our injured tissue is digested, our cells then begin the healing process – creating new cells to replace the damaged ones. The end-result: repair, replacement, and closure of the wound.
Once the damaged cells are replaced and our tissue is repaired, we no longer need the pro-inflammatory cytokines or COX-2 enzymes. As our tissues become more and more repaired, the number of cytokines and COX-2 enzymes present slowly begin to decrease.
And that’s a quick summary of the acute wound-healing process. In minor injuries – like a paper cut or a stubbed toe – we typically heal perfectly and without issue. Our cytokines and COX-2 enzymes arrive onsite, signal inflammatory cells to digest our injured tissues, and then our bodies make new cells, repair the injury, and those cytokines and COX-2 enzymes slowly disappear.
However, there’s one distinction we need to make…
An acute inflammatory response is much different than a chronic inflammatory response.
In Chronic Inflammation, Cytokines And COX-2 Enzymes Never Go Away
In an acute injury, cytokines and COX-2 enzymes eventually go away. In chronic inflammation – the kind of inflammation we see in ulcers, or infections that won’t heal, or even autoimmune diseases – these cytokines and COX-2 enzymes don’t disappear. In fact, they stay chronically elevated. And the result? Those tissues stay chronically inflamed.
Unfortunately, chronic inflammation is part of the hair loss cascade.
While the “source” of the inflammation remains mysterious, there’s evidence that chronic scalp inflammation – either from bone growth, mechanical tension, genetic predisposition, or an unidentified factor – contributes to scalp scarring, and that this scalp scarring eventually chokes our hair follicles of blood, oxygen, and nutrients… shrinking the follicles and leading to baldness.
The net: if we want to keep our hair, we absolutely have to minimize the chronic inflammation in our scalps.
And since the triggers of chronic scalp inflammation are elusive, the best way we currently know how to do this is to reduce the proteins and enzymes involved in the pro-inflammatory process.
In other words, if we want to stop the chronic inflammation that precedes hair loss, we need to reduce the pro-inflammatory cytokines and prostaglandins (as a result of increased COX-2 enzyme activity) that continuously encourage that inflammation.
Enter rosemary oil… and its anti-inflammatory mechanisms which help fight hair loss.
Rosemary Oil Decreases Pro-Inflammatory Cytokines And Prostaglandins To Help Fight Chronic Inflammation (And Hair Loss)
Two notable examples of pro-inflammatory cytokines are 1) interleukins, and 2) tumor necrosis factor.
In rat models, scientists have demonstrated that ethanolic and rosmarinic acid (two compounds inside rosemary oil) not only reduce COX-2 (and thereby prostaglandin) activity, but they also reduce the pro-inflammatory cytokines tumor necrosis factor alpha and interleukin beta.
Furthermore, certain polyphenolic compounds derived from rosemary have been shown to reduce neutrophil influx into inflamed tissue and lower the excretion of inflammatory cytokines.
In other words, rosemary oil can significantly dampen the inflammatory process. And when it comes to chronic inflammation and hair loss – the more we can dampen that inflammation, the better our odds of stopping hair loss and recovering significant amounts of hair.
2. Rosemary Oil Is Antibacterial
Despite what we our eyes see, microorganisms are currently crawling across every surface of our bodies. And while most skin-surface bacteria are innocuous (or even beneficial), some can produce inflammatory byproducts that increase inflammation in our tissues. And when pro-inflammatory bacteria and fungi colonize our scalps, they can create a chronic inflammatory state – the same state that kickstarts the hair loss process.
Fortunately, rosemary oil can help.
Rosemary Oil Helps Fight Off Pro-Inflammatory Microorganisms In Our Scalps
Some studies show that rosemary extracts are antimicrobial, and can significantly reduce the colony sizes of pathogenic bacteria (like Staphylococcus aureus) and biofilms (clumps of bacteria stuck to a surface – like skin).
In other words, rosemary oil might help fight hair loss by killing off the bacteria that puts our scalps in a chronically inflamed state. And when combined with its anti-inflammatory mechanisms – this can be a one-two punch to help stop hair loss in its tracks.
3. Rosemary Oil Reduces DHT Levels
We’ve all heard of the “dreaded” hormone DHT and its relationship to hair loss. Evidence strongly suggests that increased scalp tissue DHT precedes hair follicle miniaturization and contributes to hair thinning and baldness.
Fortunately, rosemary oil may reduce tissue DHT levels.
Rosemary Oil May Reduce Tissue DHT By Blocking Androgen Receptor Activity
This study evaluated the anti-androgen effects of rosemary leaf extract on hair growth in mice. These mice had their dorsal areas shaved and were treated with testosterone (a precursor of DHT) in order to interrupt hair regrowth. A subset of mice were then treated with topical rosemary leaf extract to see if it would have any impact on the rate at which their hair regrew.
The findings? The rosemary-treated mice showed improved hair regrowth, which the investigators attributed to the inhibitory effect of the rosemary extract on androgen receptors.
Androgen receptors are the places inside a cell where DHT binds. I wrote about androgen receptors here, but to recap: if a cell has no androgen receptor, testosterone can’t convert to DHT and then bind to that tissue site.
Many people are already experimenting with powerful androgen receptor blockers – like spironolactone – to help fight hair loss (and with some success). But unfortunately, synthetic androgen receptors are too powerful – and despite their benefits for hair recovery – often exert feminizing effects. For instance, men who are becoming women often use spironolactone to reduce androgen activity and help aid their gender transition.
Fortunately for us, these anti-androgenic effects also exist in the natural extract from Rosemary – and without the feminizing side effects. And the less DHT that converts in our scalp tissues, the better our chances for hair recovery.
4. Rosemary Oil May Prevent (Or Reduce) Fibrosis
Fibrosis (scar formation) is one of the biggest roadblocks to successfully treating pattern hair loss. It’s the end-result of long-standing chronic inflammation in the scalp. And in pattern hair loss, fibrosis occurs around the hair follicles – which decreases blood flow, oxygen, and nutrient levels – and essentially “chokes” out the hair follicle. The final result: a shiny (scarred) scalp, and miniaturized (or dormant) hair.
The good news? Rosemary oil helps prevent fibrosis – and may even stop this process from happening.
Rosemary Oil’s Acids May Protect Against Scar Tissue Formation (By Inhibiting TGFβ-1)
There aren’t any known studies describing the effects of rosemary oil on follicular fibrosis. With that said, multiple rat studies have shown that polyphenols within rosemary – such as rosmarinic acid – are protective against scar formation in other organs like the heart and liver.
One study evaluated the protective effects of rosmarinic acid on scar formation in rats with experimentally induced heart attacks. The investigators found that rats treated with rosmarinic acid had improved heart function, decreased cardiac scar tissue size, and reduced expression of collagen.
Other rodent studies showed that rosmarinic acid can reduce scar tissue formation in chemically-induced liver fibrosis, and through a variety of signaling pathways… the most notable of which is a reduction in the expression of transforming growth factor beta one (TGFβ-1) – a signaling protein that’s elevated in balding scalp tissues.
The net: rosemary oil decreases TGFβ-1, which attenuates scar tissue formation and helps stop the hair loss cascade.
5. Rosemary Oil May Increase Blood Flow
A byproduct of perifollicular fibrosis (scalp scarring around hair follicles) is a reduction in blood flow to our hair follicles. This is actually a huge factor in pattern hair loss – because without blood flow, we get less oxygen and nutrients to our hair follicles.
Fortunately, rosemary oil not only helps prevent fibrosis, but it also increases vasodilation in the areas in which it’s applied.
Rosemary Extract Can Increase Blood Vessel Diameter At Injury Sites
In this study, researchers examined the effects of rosemary extract on rats that had received soft-tissue reconstruction surgery with skin flaps.
Skin flaps are frequently associated with skin necrosis (skin death) due to their compromised blood flow. The investigators found that rats treated with rosemary extract under the skin had better skin graft survival than rats that were not treated.
Moreover, the rats receiving rosemary extract were also found to have larger diameter blood vessels. And what did the researchers infer? The vasodilatory effects of rosemary extract were largely responsible for improved skin graft survival.
Ironically, increased vasodilation is the exact mechanism of action that minoxidil (Rogaine) may work… Maybe those researchers who tested rosemary oil vs. minoxidil were onto something…
So… Should We Use Rosemary Oil For Hair Loss?
The short answer is: maybe! And beyond the evidence already presented, there’s one reader’s anecdote who did this and saw results.
Before-After Photos From Someone Using Rosemary Oil + Another Intervention
This person decided to commit to the first book’s scalp stimulation techniques (mainly, the massages). But he took it a step further… He also combined these massages with the application of rosemary oil.
Over the course of two years, he demonstrated some impressive results.
As such, perhaps there might be hair regrowth synergies with this dual approach: massaging + rosemary oil.
Can We Explain The Above Hair Regrowth Results With Actual Studies?
Interestingly, these results start to make sense once we look at evidence demonstrating the combined efficacy of mechanical stimulation with certain hair loss topicals.
For instance – just look at this study measuring the combined effectiveness of dermarolling plus Rogaine (we’ll get to why this is relevant in a minute).
The study sought to determine which treatment is more effective for hair regrowth: Rogaine by itself, or Rogaine + once weekly dermarolling (wounding) sessions.
As we already know, Rogaine is a vasodilator – just like rosemary oil. And dermarolling (or microneedling) is another form of mechanical stimulation. In other words, the mechanisms of action within this hair regrowth study match up to the purported mechanisms of action of rosemary oil plus massaging.
So what were the results?
After twelve weeks, the Rogaine + once weekly dermarolling sessions resulted in 4x the hair regrowth of just Rogaine alone…. And those results were significant.
Just check out the before-after photos:
Remember: Rogaine and rosemary oil are both vasodilators. Dermarolling and massaging are both forms of scalp mechanical stimulation.
Two different hair loss treatments; yet two similar mechanisms of action at play. And when we compare those photo sets to our one-off case study, it’s harder to deny that these mechanisms of action may promote a strong, synergistic hair regrowth effect.
The bottom line: research shows that mechanical stimulation increases the efficacy of vasodilators like Rogaine or rosemary oil. Combining both mechanical stimulation and a vasodilator might be better than just doing one (or the other). And that means that rosemary oil might be a critical adjunct to your hair recovery regimen… especially if you’re using it in conjunction with mechanical stimulation exercises.
At the same time, we can’t necessarily say that microneedling and massaging elicit the same sort of inflammatory responses. After all, microneedling creates acute inflammation at the top-most layers of the scalp, whereas massaging might elicit less inflammation here, yet more inflammation in deeper scalp layers depending on how hard you go. There’s also the argument that microneedling simply increases topical absorption via micro-wounding, which massages may not necessarily do.
So, there’s still much to be explored before we can actually claim that microneedling + Rogaine is similar mechanistically to massaging + rosemary oil. As research emerges, I’ll keep this article updated.
Summary: Will Rosemary Oil Stop Hair Loss And Regrow Hair?
Based on the evidence, rosemary oil has a mild effect on pattern hair loss – one that’s equivalent to 2% minoxidil. And while rosemary oil may make a good “natural” alternative to Rogaine, it’s our belief that it probably won’t regrow a significant amount of hair – at least not on its own.
With that said, mechanistic and animal studies have found that rosemary oils and its extracts may reduce inflammation, exert antibacterial effects, reduce androgen activity, prevent fibrosis, and increase blood flow… all of which may help slow or stop hair loss while simultaneously encouraging hair regrowth.
And if we extrapolate from anecdotes and related studies, rosemary oil’s hair regrowth effects may be enhanced if combined with mechanical stimulation exercises like massaging or microneedling. So if you’re going to use rosemary oil, you should probably use it in conjunction with mechanical stimulation.
Rosemary oil is well-absorbed in the gastrointestinal tract and skin. But when it comes to hair regrowth, most of the literature only studies its topical application. I don’t know if ingesting rosemary oil is a good idea. The reality is that too high of a concentration of its volatile oils will probably irritate your stomach, and maybe even make you sick.
So if you’re going to use rosemary oil for your hair, stick to topical applications. Apply a generous amount twice-daily (just like Rogaine), and leave it in overnight if you can.
Lastly, there aren’t really any studies comparing rosemary oil’s effectiveness for hair regrowth versus other essential oils. The truth is that there may be a better vasodilator out there… And some evidence suggests that peppermint oil (from the same plant family as rosemary) may also encourage hair growth (but unfortunately, only in animal studies).
Don’t expect any miracles with rosemary oil, and try to combine it with other interventions to maximize its use as an adjuvant therapeutic for hair loss.
Rob English is a researcher, medical editor, and the founder of perfecthairhealth.com. He acts as a peer reviewer for scholarly journals and has published five peer-reviewed papers on androgenic alopecia. He writes regularly about the science behind hair loss (and hair growth). Feel free to browse his long-form articles and publications throughout this site.