Here’s What the Science Says About Using Rosemary Oil for Hair Growth
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If you’re on a mission to fill in bald spots or a thinning ponytail, you’ve probably come across rosemary oil as a DIY solution to make your hair grow faster. A bunch of people on TikTok swear by the trendy treatment (videos about it have more than 3 billion views) and we see the appeal: You can buy rosemary essential oil for around $10, it doesn’t have as many potential side effects compared to medications like Rogaine, and rubbing it all over your scalp supposedly leads to thicker, longer hair.
That’s the key word here: Supposedly. If you’re as skeptical about buzzy wellness hacks as we are, you might question whether rosemary oil is just another fleeting fad or the hair hero you’ve been searching for. To find out the truth, we asked three board-certified dermatologists what this ingredient can—and more importantly, can’t—do so that you’re not misled by false promises.
What does the science say about using rosemary oil for hair growth?
There is some substance (and peer-reviewed research) behind the alleged magic of this essential oil, but it’s pretty limited. One of the strongest pieces of supporting evidence is a clinical trial published in 2015, in which researchers explored the effects of rosemary oil on 100 men experiencing androgenetic alopecia, the leading cause of hair loss in men and women. Interestingly, participants who gently massaged their scalps with rosemary oil (twice a day for six months) had just as much hair growth as those who applied 2% minoxidil (the active ingredient in Rogaine—one of the best, most researched hair loss treatments).
There are smaller studies with similarly intriguing results: This one, also from 2015, included 40 men and women with alopecia areata (an autoimmune disease that causes bald patches) and found that more than half of the 20 participants who rubbed a blend of essential oils (rosemary, thyme, cedar, evening primrose, and lavender) and carrier oils (like jojoba, grapeseed, and almond, among others) onto their scalp nightly for three months had at least 51% hair regrowth in their bald spots. Meanwhile, none of the 20 people in the placebo group (who only used the carrier oils) saw these results.
In another study published in 2022, researchers treated hairless rats with either 2% minoxidil or “oleogel” (made of olive oil and beeswax) infused with rosemary essential oil, cedarwood essential oil, or a combination of both. After doing this for six weeks, they found that the oleogel with just rosemary oil had similar “pronounced” effects to minoxidil in terms of improving the rodents’ hair length and thickness. (But it’s worth emphasizing that animal studies are super preliminary, so these results can’t be applied to humans yet.)
While this may all sound (sort of) promising, it’s certainly not proof that rosemary oil will help your hair grow, Michael Cameron, MD, founder of Cameron Dermatology in New York City who specializes in hair loss, tells SELF. “First of all, none of these studies are large,” Dr. Cameron says. “When you do a clinical trial, it’s usually hundreds, if not thousands of people.” (Having a larger and more diverse group of participants is more representative of the full population being studied and, therefore, more likely to be accurate.)
Plus, the smaller studies above used a combination of essential oils in their experiments, so it’s hard to know how big of a role rosemary, specifically, played in the results. The research also looked at the effects of these oils when applied directly on the scalp—not when they’re mixed in with OTC shampoos, conditioners, or serums with varying formulations. So, just because a hair product claims to be “volumizing” or “lengthening” because it contains rosemary oil, that doesn’t mean it’ll work (though it might smell nice!).
Another major caveat: While rosemary oil led to the same hair growth as 2% minoxidil in the first 2015 clinical trial noted above, the results weren’t that visibly impressive for either treatment. (We’re talking about a subtly noticeable increase in the number of strands filling in versus a suddenly full head of hair). It’s standard practice for dermatologists to prescribe a higher concentration of Rogaine, Carmen Castilla, MD, a board-certified dermatologist and clinical associate professor at the Icahn School of Medicine at Mount Sinai in New York City, tells SELF: “We usually recommend 5% minoxidil, and when you compare 2% and 5%, the latter is significantly more effective.”
How (and when) rosemary oil could theoretically help support hair growth
Right now, there isn’t enough evidence to suggest that rosemary oil can magically fix sparse patches or stop a receding hairline. Even the experts we spoke with aren’t exactly sure how it could work—but they have a few theories.
Rosemary oil (and specifically, the carnosic acid and carnosol in it) has anti-inflammatory and antioxidant properties, which derms believe might help stimulate blood flow to the hair follicles, Lindsey Zubritsky, MD, a board-certified dermatologist at Premier Dermatology and Skin Cancer Center in Ocean Springs, Mississippi, tells SELF. Simply massaging your scalp (with or without rosemary oil) can also play a role in boosting circulation, research shows. “Increased blood flow equals more nutrients to the scalp, which could help with hair growth, strength, and thickness,” Dr. Zubritksy explains.
Another theory, she says, revolves around rosemary oil’s anti-inflammatory and antimicrobial properties, which could possibly help support a “healthy scalp environment.” (An inflamed scalp can weaken hair follicles and potentially result in shedding.)
Again, there’s no concrete science to back any of this up fully, but even if the routine of applying rosemary oil to your scalp does have these effects, all three experts caution that it won’t help all types of thinning or balding. “There are actually various types of alopecia and hair loss,” Dr. Cameron explains—each with different causes that require tailored treatments.
Research shows that people with androgenetic alopecia, for example, might have better luck with topical solutions like minoxidil compared to folks whose shedding is triggered by an autoimmune disorder or another underlying condition. The latter would call for interventions that address the root of the health issue. (In the case of alopecia areata, steroid injections are a common treatment.)
Are there any risks to be aware of when using rosemary oil on your scalp and hair?
If you still want to give it a try, there aren’t many unpleasant side effects to worry about. However, “I would be careful if you have a history of allergic reactions or scalp sensitivity due to conditions like psoriasis or eczema,” Dr. Zubritsky says, since rosemary oil can sometimes cause contact dermatitis, an unpleasant rash that’s triggered when your skin has direct contact with certain irritants or allergens, like essential oils or added fragrances. (This is why you should always patch test any new hair product on a small area of your skin before using it all over your head.)
Also, rosemary oil isn’t necessarily suitable for all hair types. People with fine hair may feel like their strands are being weighed down from the greasy, thick consistency, both Dr. Zubritsky and Dr. Castilla say.
The bottom line
If you’ve heard a lot of buzz about rosemary oil for hair growth, remember this: “Overall, there are just so many unknowns,” Dr. Cameron says. “We don’t know if rosemary oil for sure causes hair thickening. Even if it does, we don’t know the concentration that’s required to see a difference.” (Keep in mind, participants in the strongest study above had to apply it twice a day for at least six months—which many of us may not have the time or patience for.) “I don’t think it hurts to use rosemary oil, but it’s hard to know how much it really helps,” he adds. In other words: It may not be worth it.
We know that’s a huge bummer: Hair loss can hit really hard emotionally and make you feel frustrated, insecure, and even defeated. If you’re determined to fill in sparse spots on your scalp or stop significant shedding, the smartest move is to see a board-certified dermatologist (or a primary care doctor) to get to the root of the issue. A medical professional can suggest legit treatments with way more science behind them than rosemary oil.
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Originally Appeared on SELF
