Rosemary oil vs minoxidil: what the one study actually found
IngredientsUpdated 9 min read
A 2015 trial of 100 men is the entire basis for the claim that rosemary oil works as well as minoxidil. Here is what it measured, what it did not, and why a rosemary shampoo is not the same thing as the trial.
Rosemary oil is the most searched botanical for hair growth, and the reason is a single study. Published in 2015 in the journal Skinmed, it compared rosemary oil to minoxidil 2 percent in men with androgenetic alopecia over six months and found no significant difference between them. That sentence has been repeated in thousands of articles, videos and product descriptions. Almost none of them describes the study.
This one does. The study is real, it is reasonably designed, and it is more interesting than the summary. It is also much smaller than its influence, and the leap from it to a rosemary shampoo is one the data does not support.
What the trial was
- 100 men with androgenetic (pattern) hair loss, randomised to two groups of 50.
- One group applied rosemary oil to the scalp; the other applied minoxidil 2 percent. Both twice daily, for six months.
- The outcome was hair count in a defined area of scalp, measured by photograph at baseline, three months and six months.
- Neither group showed a significant increase in hair count at three months. Both groups showed a significant increase at six months, compared with their own baseline.
- At six months, the difference between the two groups was not statistically significant.
- Scalp itching was more common in the minoxidil group.
That is the entire finding. Rosemary oil, applied twice daily for six months, produced an increase in hair count that was not statistically distinguishable from minoxidil 2 percent applied the same way.
What the trial was not
The gaps matter more than the headline, because they are what determine whether the finding transfers to the bottle in your hand.
| The trial | What people conclude from it |
|---|---|
| Compared against minoxidil 2 percent, the lower strength. The standard for men is 5 percent, which performs better in head-to-head trials. | Rosemary works as well as minoxidil. |
| Had no placebo group. Hair count rises in placebo groups of hair loss trials too, sometimes substantially. | Rosemary caused the increase. |
| Applied rosemary oil, left on the scalp, twice a day, for 180 days. Roughly 360 applications with hours of contact each. | A rosemary shampoo, rinsed off after 60 seconds, does the same thing. |
| Studied 100 men with one diagnosis. No women, no telogen effluvium, no other conditions. | Rosemary helps with hair loss in general. |
| Measured hair count in one area. Not thickness, not the whole scalp, not what participants thought of their hair. | Rosemary gives visibly thicker hair. |
| Reported by one group, published in one journal, and has not been replicated at scale. | It is settled. |
The rinse-off problem
Even taking the trial at face value, it tested leave-on oil. The exposure was hours of skin contact twice a day. A shampoo containing rosemary extract is on the scalp for a minute or two and then goes down the drain, and the extract in a shampoo is present at a fraction of the concentration of the oil used in the trial. There is no study of rosemary in a rinse-off product and hair count. Any brand implying that its rosemary shampoo delivers the trial's result is quoting a leave-on protocol for a rinse-off product.
This applies to every botanical in every cleanser, including the ones in ours. A rinse-off product is a cleanser first. Whatever its botanicals do in that window, it is not what a six-month leave-on trial measured.
A plausible mechanism, unproven
Rosemary's main active constituents include carnosic acid and rosmarinic acid, which are antioxidants, and 1,8-cineole, which increases local blood flow. There is laboratory work suggesting rosemary extract may interfere with the binding of dihydrotestosterone, the hormone that drives pattern hair loss, and mouse studies showing improved regrowth. None of this is a human trial, and mechanism is not efficacy. The 2015 study is the only human data of note.
If you want to try it anyway
The trial's protocol is reproducible at home, and it is the only version of rosemary with data behind it.
- Use rosemary essential oil diluted in a carrier oil. Essential oils applied neat can irritate and sensitise the skin. A common dilution is 2 to 5 drops per tablespoon of carrier, though the trial's exact formulation is not fully specified in the paper.
- Patch test on the inner forearm for 48 hours first.
- Apply to the scalp, not the hair, and leave it on. Twice daily is the trial's schedule; once daily is what most people sustain.
- Commit to six months. The trial saw nothing at three, which is consistent with how the hair cycle works.
- Photograph a fixed area of scalp at baseline and monthly in the same light. Hair count is the outcome that was measured; it is the one you should measure.
- Do not stop a prescribed treatment to do this. Rosemary has one small trial. Minoxidil has decades of data and regulatory approval. Ask a dermatologist before swapping.
The honest summary
One small trial in men found leave-on rosemary oil comparable to low-strength minoxidil over six months, without a placebo group. That is worth knowing and it is not nothing. It is also not evidence that a rosemary shampoo does anything for hair count, and it is not evidence about women, about shedding, or about the 5 percent minoxidil that dermatologists actually recommend. Rosemary in a cleanser is a pleasant, mildly stimulating, antioxidant botanical. Describe it as that and the description is true.
Common questions
- Does rosemary oil work as well as minoxidil?
- One 2015 trial of 100 men found leave-on rosemary oil not statistically different from minoxidil 2 percent after six months. It had no placebo group, used the lower minoxidil strength, and has not been replicated at scale.
- Does rosemary shampoo help hair growth?
- There is no study of rosemary in a rinse-off product. The 2015 trial applied oil to the scalp and left it on twice a day. A shampoo's minute of contact is not the same exposure.
- How long does rosemary oil take to work for hair?
- In the trial, neither rosemary nor minoxidil produced a significant change at three months. Both did at six. Anyone promising results in weeks is contradicting the only study they can cite.
- Does rosemary oil work for women's hair loss?
- The trial included only men with androgenetic alopecia. There is no comparable trial in women. The mechanism is plausible for pattern hair loss in either sex, but plausible is not tested.
- Can I put rosemary essential oil directly on my scalp?
- Dilute it in a carrier oil and patch test first. Neat essential oils can irritate and sensitise skin, and the scalp is not exempt.
Sources
YoraCare is a cosmetic scalp-care product. It is not a medicine and is not intended to diagnose, treat, cure, or prevent any disease or medical condition, including hair loss. Individual results vary. If you have a scalp or hair condition, are pregnant or breastfeeding, or have known sensitivities, consult a qualified healthcare professional before use.