Both rosemary and mint (specifically peppermint) show genuine promise for hair growth, backed by a small but growing body of research. Rosemary oil performed comparably to 2% minoxidil in a six-month clinical trial on people with pattern hair loss, and peppermint oil dramatically increased hair follicle counts in animal studies. Neither is a guaranteed fix, but the evidence is stronger than for most natural hair remedies.
What the Research Shows for Rosemary
The most compelling evidence for rosemary oil comes from a 2015 clinical trial that compared it head-to-head against minoxidil 2%, one of the most widely used hair loss treatments. Sixty people with androgenetic alopecia (the most common type of pattern hair loss) applied either rosemary oil or minoxidil to their scalps daily for six months. By the end of the trial, both groups saw significant increases in hair count compared to baseline, and there was no meaningful difference between the two groups.
That’s a notable result. Minoxidil is an FDA-cleared treatment with decades of data behind it, so matching its performance in even a small trial is significant. The catch: this is still just one study with 60 participants, so it’s not the same level of proof you’d get from a large pharmaceutical trial. Still, it’s one of the few natural remedies that has been tested directly against a proven treatment and held its own.
Rosemary oil appears to work by improving blood flow to the scalp and extending the anagen phase, which is the active growth stage of your hair cycle. It also has anti-inflammatory and antimicrobial properties that support overall scalp health, which matters because an inflamed or irritated scalp can contribute to hair thinning.
What the Research Shows for Peppermint
Peppermint oil has one widely cited study, published in Toxicological Research, that tested a 3% concentration on mice. The results were striking: after four weeks, the peppermint oil group had 740% more hair follicles than the saline control group and 307% more than a jojoba oil group. Its performance was comparable to 3% minoxidil.
The menthol in peppermint oil creates that familiar tingling sensation on the scalp, and that cooling effect reflects real vasodilation, meaning it widens blood vessels and increases circulation to the area. Better blood flow delivers more oxygen and nutrients to hair follicles, which can stimulate growth.
The important caveat here is that this study was conducted on mice, not humans. Animal results don’t always translate to people, and no large human clinical trial has yet confirmed peppermint oil’s effects on hair growth. The mechanism is plausible and the animal data is encouraging, but it’s a step behind rosemary in terms of human evidence.
How Long Before You See Results
Hair grows slowly, and any treatment, natural or pharmaceutical, takes months to show visible changes. This is because hair follicles cycle through growth, rest, and shedding phases, and you need enough time for follicles to enter and stay in an active growth phase before new density becomes noticeable.
In the rosemary versus minoxidil trial, both groups saw significant improvements at the six-month mark but not at three months. This timeline is consistent across nearly all hair growth treatments. Expect to use rosemary or peppermint oil consistently for at least three to six months before judging whether it’s working. If you stop after a few weeks because you don’t see changes, you haven’t given it a fair test.
How to Use Them Safely
Essential oils are highly concentrated and should never be applied undiluted to your scalp. Undiluted rosemary or peppermint oil can cause irritation, redness, or allergic reactions. The general guideline for leave-on scalp products is a 2% dilution, which works out to roughly 12 drops of essential oil per ounce of carrier oil. Jojoba, coconut, and sweet almond oil are all common carrier choices. For anything above 3%, the risk of irritation rises without clear added benefit, and concentrations above 5% are not recommended for skin application.
To apply, mix a few drops of rosemary oil, peppermint oil, or both into your carrier oil. Massage the blend into your scalp using your fingertips for about five minutes. You can do this a few times per week as a standalone treatment, or add a couple of drops of essential oil to your shampoo and massage it in during your regular wash. The massage itself may also help: gentle, consistent scalp massage increases local blood flow to the follicles.
Before using either oil broadly on your scalp, do a patch test. Apply a small amount of your diluted mixture to the inside of your forearm and wait 24 hours. If you see redness, itching, or a rash, that oil isn’t a good fit for you. Rosemary oil is well tolerated by most people, but allergic reactions do occur.
Using Both Together
There’s no research specifically testing rosemary and peppermint oil as a combined treatment, but their mechanisms complement each other. Both improve scalp circulation, and rosemary’s anti-inflammatory properties pair well with peppermint’s vasodilating effect. Many people blend the two into a single carrier oil and use them together. Just keep your total essential oil concentration at or below 3% of the overall mixture. If you’re using two oils, split that percentage between them rather than doubling up.
Who Benefits Most
The existing research has focused primarily on androgenetic alopecia, the genetic pattern of thinning that affects both men and women. If your hair loss falls into this category, the evidence is most relevant to you. For hair thinning caused by stress, nutritional deficiencies, hormonal changes, or medical conditions, these oils may still support scalp health and circulation, but they won’t address the underlying cause.
It’s also worth keeping expectations realistic. The rosemary trial showed improvement comparable to a treatment (2% minoxidil) that produces modest, not dramatic, regrowth for most users. These oils can meaningfully slow thinning and encourage some regrowth, but they’re unlikely to reverse significant hair loss on their own. People in earlier stages of thinning tend to see the best results, simply because their follicles are still active enough to respond.