Rosemary Oil vs Minoxidil: Reading the One Trial Everyone Cites

Rosemary oil versus minoxidil rests on a single paper, and almost everything said about it online is a summary of a summary. The trial is real, it is randomised, and its design contains one gap that changes what it can prove. On this site's scale rosemary oil scores five out of ten — the bottom of the mixed band, and the best any leave-on cosmetic active manages here.

What the trial actually did

Panahi, Taghizadeh, Marzony and Sahebkar published in Skinmed in 2015 (volume 13, pages 15 to 21). People with androgenetic alopecia were randomly assigned to rosemary oil (fifty people) or minoxidil 2% (fifty people) for six months, with efficacy and safety visits every three months and a standardised professional microphotographic assessment at baseline, three months and six.

The results, in the authors' own terms: no significant change in mean hair count at three months in either group; a significant increase in both groups at six months compared with baseline and with three months; and no significant difference between the groups at either time point. Scalp itching rose in both groups and was significantly more frequent in the minoxidil group.

The gap in the design, and why it decides the grade

There was no third arm. Nobody in this trial was left untreated, and nobody received a placebo. That single fact governs how the result can be read: when both groups rise, the trial cannot tell you whether the rise came from the treatments or from six months passing in a group of people who had just enrolled in a hair study and knew it.

"No significant difference between rosemary oil and minoxidil" is therefore not the same sentence as "rosemary oil works as well as minoxidil", even though it is endlessly quoted as though it were. A trial with no untreated arm can show two things are similar; it cannot show that either one does anything. On our four-point first question that is a one, not a two — an active-comparator study with no control group.

It scores well on the other questions, which is how it reaches five: hairs were counted from standardised microphotographs, the authors are academic with no seller on the byline, and a leave-on oil is at least the right form. What is sold as rosemary shampoo is not, and that costs the last point.

What other people who read it concluded

Two independent 2025 publications reached the same place from different directions. The Canadian consensus on androgenetic alopecia — eleven physicians, forty-five interventions assessed by a Delphi process — lists rosemary oil among seventeen interventions it does not recommend. And a qualitative review of alopecia misinformation in Skin Appendage Disorders, by a dermatology group in Cork, names rosemary oil among the unfounded alternative therapies commonly touted online, alongside biotin, horsetail extract and shark cartilage.

Neither of those is proof that rosemary oil does nothing. They are what the people whose job it is to read this literature concluded after reading it, which is worth knowing before a social-media clip makes the decision for you.

Why one small trial became this famous

Nothing about the 2015 paper explains its reach. It is a single-centre study in a specialist journal, and for several years almost nobody outside dermatology had heard of it. What changed is that it is the only paper in this category that can be summarised in a sentence a short video can carry: as good as minoxidil. That sentence is a compression of "no significant difference between the groups", and the compression quietly loses the missing control arm along the way.

The 2025 review of alopecia misinformation in Skin Appendage Disorders describes the wider shape of this: patients search online, meet poor-quality sources, and come away with false causes, criticism of conventional treatments and unfounded natural remedies. Rosemary oil sits in that list not because the trial is fraudulent — it is a real, published, randomised study — but because of what gets said about it afterwards.

Prescription and over-the-counter are different questions

One thing this page deliberately will not do is tell you whether to use minoxidil, at what strength, or how. Topical minoxidil has its own approved label and its own warnings, and the trial above used the 2% strength rather than the 5% most people mean. Those are matters for the product's label and for a pharmacist or doctor — this site covers what the evidence says about non-prescription topicals, not how to take a drug.

If you are going to try it anyway

Plenty of people will, and it is a cosmetic rather than a medicine. Two honest notes. Essential oils can irritate skin and cause contact allergy, so a patch test on a small area first is sensible, and anything applied near the eyes deserves care. And a rinse-off rosemary shampoo is not the preparation that was studied — see why contact time decides what a shampoo can do.

Where rosemary sits against everything else in this aisle, with each grade broken into its parts, is in the best shampoo for hair loss, graded on published evidence.