Rosemary oil for hair growth: what the London evidence actually says
Rosemary oil went viral for a reason — but the reason is not what TikTok thinks. Here is the evidence, the right protocol, and the limits.
Maya Levin
IAT Trichologist · East London
In short
- The 2015 Karadeniz trial showed rosemary oil matched 2% minoxidil at 6 months — but not 5%.
- It works via vasodilation and anti-androgen activity, not 'thickening' as marketed.
- Always dilute to 2–3% in a carrier oil; neat application burns the scalp.
- Best results combine rosemary oil with microneedling and a proven medical treatment, not as a replacement.
Rosemary oil is the single most-searched hair ingredient in London right now. The interest is justified — the evidence is real — but the way TikTok is using it is not how trichologists recommend it.
What the actual study showed
The 2015 Karadeniz randomised trial compared rosemary oil to 2% minoxidil over six months in 100 men with androgenetic alopecia. At month six, both groups showed statistically significant hair count increases, with no difference between them. Importantly, the rosemary group reported less scalp itch.
This is the entire evidence base most marketing rests on. It is genuinely promising, but it was a single trial, against the weaker 2% formulation, in men only.
How to use it properly in London water conditions
London's hard water already irritates the scalp. Applying neat rosemary oil — as many TikTok videos suggest — usually makes things worse.
- Dilute to 2–3%: roughly 6–10 drops of rosemary essential oil per 30 ml carrier (jojoba, argan or castor).
- Apply 2–3 times per week, massaged into the scalp for 5 minutes.
- Leave for 30 minutes minimum, ideally overnight, then shampoo with a sulphate-free cleanser.
- Combine with weekly 0.5 mm microneedling for synergistic effect.
- Allow 4–6 months before judging results — exactly the same timeline as minoxidil.
Frequently asked
Common questions
Is rosemary oil as good as minoxidil?+
It matched 2% minoxidil in one trial. It has not been shown to match 5% minoxidil or finasteride. For mild early-stage loss it is a reasonable starting point.
Can I use rosemary oil with minoxidil?+
Yes, on alternate days. Many London trichologists recommend this combination for sensitive scalps.
Does rosemary oil work for women?+
Likely yes — the mechanism is the same — but the published trial was male-only. Anecdotal results in women are encouraging.
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