There are very many social media posts and videos stating that Rosemary oil helps hair loss. Is there any truth in that backed by scientific studies?
So far, there has been only one randomised study done comparing Rosemary oil with Minoxidil 2% which was published in Skinmed Vol 13 in January 2015.
In summary, 100 men were recruited of which 50 were randomly selected to use 1ml rosemary oil twice a day and the other 50 were given to use 1ml minoxidil 2% twice a day. (There was no group of men who were not randomly given a solution that contained neither minoxidil nor rosemary solution) for 7 months.
A standardised professional microphotographic assessment of each volunteer was taken at the start, after 3 and 6 months of the study. Changes in these photographic assessment formed the primary outcome measure. The volunteers were also given patient satisfaction questions to answer at 3 months and 6 months (which were scored) about their treatment and the answers were also part of the measuring the outcome of the study.
The result showed that at 3 months, there was no improvement in hair growth in either group but at 6 months, there was some improvement in both groups. Itching occurred in both groups with minoxidil group reporting greater itching events compared to Rosemary oil group..
Although the study was a step in the right direction, why should we be cautious about this study?
Firstly, there was no control group (of men not using either product) to compare results/effects with.
Secondly, essential oil content of rosemary oil available to buy ranges from 0.5% to 2.5%. It is not standardised and hence one does not know what strength and brand of rosemary oil to use. The strength of Rosemary oil used in the study was 1.8%.
Thirdly, The self assessment questions that were answered by volunteers about how they thought their hair was after treatment may have added to psychosocial perceptions of their hair growth.
Fourth, importantly, all the volunteers were men and therefore comparing a suboptimal dose of 2% minoxidil (on men) with Rosemary oil is not accurate. A randomised clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men published in the Journal of American Academy of Dermatology in 2002 showed that minoxidil 5% had 45% more hair regrowth than using minoxidil 2%. Therefore why was rosemary oil not compared with the correct dose of minoxidil used for men (5% instead of 2%)?
Fifth, all social media posts and videos hardly mention using rosemary oil TWICE a day for a lengthy period for any benefit.
In our view, further research is warranted to identify the active ingredients of rosemary oil and a more robustly designed clinal trial needs to be done.