Does rosemary oil regrow hair? Reading the 100-person study everyone cites

Rosemary oil is often said to “regrow hair as well as minoxidil”, and almost every video cites the same study: a 2015 trial in the journal SKINmed involving 100 men. What it actually found is that at 6 months hair counts had risen in both groups with no difference between them. But the trial had no placebo group, compared against a low-strength drug, and has never been repeated. This article reads that study piece by piece, so you know what it can and can’t tell you.

What the 2015 trial did

Panahi and colleagues (SKINmed 2015, volume 13, issue 1, pages 15-21) studied 100 people with pattern hair loss (androgenetic alopecia), randomly split into two groups.

Point	Detail
Participants	100 people with pattern hair loss; readers of the full paper report all were men, mean age about 24
Rosemary group	50 people using rosemary oil
Comparison group	50 people using 2% minoxidil
Duration	6 months, with standardised scalp photos at the start, 3 months and 6 months
At 3 months	No change in hair count in either group
At 6 months	Both groups had significantly more hair than at the start; no difference between groups
Side effects	Scalp itching rose in both groups, more often with minoxidil; dandruff, dry hair and greasy hair did not change

Why “works as well as the drug” doesn’t follow

No placebo group. Without a group using a plain oil or nothing at all, there’s no way to tell whether hair increased because of rosemary, the daily scalp massage, seasonal shedding patterns, or the way hairs were counted.

A low-strength comparison. Minoxidil comes in 2% and 5%. A 2025 network meta-analysis in men found that 5% minoxidil applied twice daily was the most effective of the over-the-counter topical options. “Not different from the weaker strength in one trial” is a long way from “can replace the drug”.

No difference is not the same as equal. Showing that two groups don’t differ statistically doesn’t prove they are equivalent. That needs a differently designed trial, usually with more people.

Not replicated. One trial in one group of people still needs independent confirmation. The other studies often quoted are lab, animal or multi-ingredient formula studies, which can’t show that rosemary oil alone helps real people.

One trial, no placebo, a weaker comparator, no replication: that is the level of evidence right now.

Worked example: the hair counts step by step

The abstract gives no numbers, but people who read the tables in the full paper report the same starting values, and a cosmetic chemist who analysed it calculated the 6-month changes like this (counts in the photographed area):

	Rosemary group	2% minoxidil group
Average at the start	122.8 hairs	138.4 hairs
Change at 6 months	about +5.5%	about +1.6%

1. Rosemary: 122.8 × 0.055 ≈ 6.8 hairs, giving about 129.6.
2. Minoxidil: 138.4 × 0.016 ≈ 2.2 hairs, giving about 140.6.
3. But at the start the groups were already 138.4 − 122.8 = 15.6 hairs apart, more than either group gained.
4. The spread in the rosemary group at the start was about ±49 hairs, so a change of 6-7 hairs is tiny next to the differences between people.
5. The analyst also pointed out that the baseline and 3-month values in the table are identical, possibly a typo; if the baseline is wrong, the 6-month result changes with it.

None of this proves the oil doesn’t work. It shows the changes were small, and one trial can’t settle the question.

If you still want to try it, do it safely

Point	How
Always dilute	A few drops of essential oil in a carrier oil or in shampoo; never neat
Patch test first	Try a small area and wait; see Patch test new products
Pregnancy	Don’t use it; if breastfeeding, ask a doctor first
Children	Keep it out of reach; keep it out of eyes and mouth
Scalp problems	With dandruff or a rash, oil on the scalp may make things worse; see Hair oiling and dandruff
Track it	Photograph the same spot in the same light every month; hair changes slowly, so don’t judge after 1-2 weeks

Common mistakes

Doing this	What happens
Applying undiluted essential oil	Irritation, allergic rash
Stopping a prescribed treatment to switch to oil	You may lose the benefit of the treatment plan; always talk to your doctor before stopping
Using it for every kind of hair loss	The trial only covered pattern hair loss; other causes need their own treatment
Trusting videos that say it’s “better than the drug”	The trial didn’t find it better, only not statistically different
Applying heavily every day until the scalp is greasy	Oil builds up on the scalp and may bring more itching or dandruff

Unusually heavy shedding, patchy hair loss, or a rash or pain on the scalp should be checked by a dermatologist. Signs that mean you should see a doctor are in Hair breakage and split ends, and when to see a doctor. This article does not diagnose or treat hair loss.

Sources

• Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial — SKINmed 2015 (Europe PMC record)
• Comparative effect of conventional and non-conventional OTC treatments for male androgenetic alopecia — Int J Mol Sci 2025 (Europe PMC record)
• Rosemary oil for hair growth — Medical News Today
• Does rosemary oil work for hair growth? The science — Lab Muffin Beauty Science