Does rosemary oil really make your hair grow?

If you have been anywhere near TikTok recently then you can’t fail to have seen an outpouring of sales for hair products containing rosemary oil which claim to make your hair grow.

We are generally suspicious of anything so seemingly faddish and so went about researching if this magical herb really does have the properties these companies are claiming it does. Does rosemary oil really make your hair grow and can it stop, or at least slow down, hair loss?

 Rosemary the plant

Rosmarinus officionalis from the mint family, originally found in warm dry sunny areas of the Mediterranean, is a fragrant, evergreen plant . Its oils are produced via steam distillation and for thousands of years has been used in cooking, aromatherapy and herbal potions.

Rosemary history and myth

 Associated with the astrological sign Leo, the element of fire, the Sun, rosemary is thought to be male in nature. The name rosemary comes from the Latin for ‘dew’ (roe) and ‘sea’ (marines) or ‘dew of the sea’. An alternative myth suggests that its name comes from the ‘Rose of Mary’, after the Virgin Mary who spread her blue cloak over a white rosemary plant turning the flowers blue.

Rosemary has been used symbolically in ceremonies for thousands of years. The ancient Greeks believed that rosemary was a gift from Aphrodite, goddess of love, which is why it appears in so many wedding bouquets.

Throughout medieval Europe rosemary was thought to ward off evil spirits and bad dreams- often being tucked under pillows. Around 1525, Blanckes herbal suggested washing in rosemary essential oils to give you a ‘fayre face.’

Rosemary is also a symbol of remembrance, in the Shakespearean play Hamlet, Ophelia hands rosemary to Hamlet saying, ‘There’s rosemary, that’s for remembrance, pray you love, remember’. For the same reason it is often used at funerals, as a pledge never to forget.

On ANZAC Day, the Australian and New Zealand day of commemoration for World War 1 and 2 , rosemary is worn to remember the sacrifices in war. It grows on the Gallipoli peninsula in Turkey, where ANZAC soldiers landed on April 25, 1915.

Rosemary the hair restorer?

 It is important to note that most of the rosemary containing products on TikTok have not been through trials so are not clinically proven. They also do not distinguish between the different types of hair loss which, as you will read below, is important. However, there is trial evidence that rosemary does help hair regrowth in male and female pattern hair (androgenic alopecia) loss and a smaller trial showing that it helps hair regrowth in alopecia areata (unknown reasons for hair loss).

First off - what is androgenic alopecia?

Androgenic alopecia (male pattern baldness and female pattern hair loss) is a common form of hair loss in both men and women affecting 30-50% of men by the age of 50 and over 10% of premenopausal women, increasing after the menopause.

In men, there is a well-defined pattern, beginning over both temples then receding to form a characteristic ‘M’ shape. Hair also thins at the top of the head, the combination of both leading to partial or complete baldness. This hair loss can start as early as the teens although is commoner in older men.

 In females the hair loss pattern is different, the hair becomes thinner at the top of the head and the middle parting widens. The hairline does not typically recede, and it very rarely leads to total baldness as it can in men. Usually in females this hair loss starts at the time of the menopause. As with male pattern hair loss, androgens play a role in female pattern hair loss, but there are other less clearly defined factors involved.

How does hair grow?

In brief each hair follicle on the scalp produces a hair strand which grows for about 2-6 years (the longer it grows the longer your hair). After growth it goes into its resting phase for several months, then falls out. The cycle then starts all over again.

Androgens are known to help control this cycle; however, it is thought that too much stimulation of the hair follicles by androgens may lead to a shorter growth period, which in turn results in shorter thinner strands of hair and ultimately hair loss.

The causes of androgenic alopecia?

 The causes of male and female pattern hair loss are thought to be a combination of both genetic and environmental factors - although there is little evidence as to what these environmental factors are. In males (and to a lesser extent females) the hair loss is related testosterone which with the help of the enzyme 5 alpha reductase is broken down into androgen hormones, particularly one called dihydrotestosterone or DHT.

Usually, the DHT stimulates the androgen receptor on the hair follicle causing normal hair growth.

Figure 1: diagram showing normal hair growth 

With the AR variant more androgen receptors are manufactured leading to an overstimulation which in turn speeds up  the growth cycle to the detriment of the hair, leading to hair loss. (4 & 5)

Figure 2: diagram showing how hair loss occurs in people with male or female pattern baldness (mutation of the AR gene)

So, what does rosemary oil do to help prevent hair loss?

Rosemary oil is known to block 5 alpha reductase, so reducing the breakdown of testosterone which in turn lowers the levels of DHT minimising the effect of this hormone on the hair follicle and so reducing hair loss.

 There are two trials supporting this hypothesis:

One in in 2013 on mice showed that rosemary oil extract helped the regrowth of hair, it was postulated by affecting androgen receptors. (1)

The second in humans in 2015 which trailed rosemary oil against minoxidil (a prescription only medication proven to help hair growth in males who have male pattern baldness) which showed that after 6 months rosemary oil worked as well in improving hair growth as 2% minoxidil. (2)

But what about other types of hair loss?

A very small trial in 1998 on 86 patients did show an improvement with people suffering from alopecia areata (hair loss not related to androgenic hormones) .

The trial showed that the group who rubbed into their scalp the essential oils thyme, rosemary, lavender, and cedar wood in a mixture of jojoba and grapeseed carrier oil did significantly improve their hair growth compared to the placebo group. The conclusion was that the combination of the above the essential oils’ thyme, rosemary, lavender, and cedar wood helped hair regrowth. They did not conclude which oil was the active ingredient or indeed whether it was all the oils or a combination of them - or even the nightly head massage! (3)

Rosemary’s antibacterial properties

 Rosemary oil is also known to have antimicrobial properties. This was backed up in a trail in 2013 (6) when researchers exposed different strains of e coli bacteria to rosemary oil and basil essential oil on Petri dishes. They found that both the rosemary oil and basil essential oils were very effective at killing the strains of E .coli bacteria. Making the reasonable assumption therefore that as bacteria cause inflammation the rosemary oil in killing the bacteria helps reduce inflammation around the hair follicle. A reduction in inflammation around the hair follicle will minimise the extent of hair loss.

 So, there you have it, rosemary, used in culinary, medicinal, and symbolic forms since records began has been brought up to speed with modern clinical trials showing that there is evidence for it working - both in helping block the overactive hormones which are linked to hair loss and in reducing inflammation on the scalp. It would appear rosemary oil really does help with hair loss! 

Sources 

1. 2013 Feb;27(2):212-7. doi: 10.1002/ptr.4712. Epub 2012 Apr 20. Promotion of hair growth by Rosmarinus officinalis leaf extract Kazuya Murata 1 , Kazuma Noguchi, Masato Kondo, Mariko Onishi, Naoko Watanabe, Katsumasa Okamura, Hideaki Matsuda

2. Skinmed. 2015 Jan-Feb;13(1):15-21. Rosemary oil vs minoxidil 2% for the treatment of androgenetic alopecia: a randomized comparative trial Yunes Panahi, Mohsen Taghizadeh, Eisa Tahmasbpour Marzony,

3. Hay IC, Jamieson M, Ormerod AD. Randomized trial of aromatherapy successful treatment for alopecia areata. Arch Dermatol 1998;134(11):1349-52.

4. Hillmer AM, Hanneken S, Ritzmann S, Becker T, Freudenberg J, Brockschmidt FF, Flaquer A, Freudenberg-Hua Y, Jamra RA, Metzen C, Heyn U, Schweiger N, Betz RC, Blaumeiser B, Hampe J, Schreiber S, Schulze TG, Hennies HC, Schumacher J, Propping P, Ruzicka T, Cichon S, Wienker TF, Kruse R, Nothen MM. Genetic variation in the human androgen receptor gene is the major determinant of common early-onset androgenetic alopecia. Am J Hum Genet. 2005 Jul;77(1):140-8. doi: 10.1086/431425. Epub 2005 May 18. Citation on PubMed or Free article on PubMed Central

5. Levy-Nissenbaum E, Bar-Natan M, Frydman M, Pras E. Confirmation of the association between male pattern baldness and the androgen receptor gene. Eur J Dermatol. 2005 Sep-Oct;15(5):339-40. Citation on PubMed

6. Sienkiewicz M, Łysakowska M, Pastuszka M, et al. The potential use of basil and rosemary essential oils as effective antibacterial agents. Molecules 2013;18(8):9334-51.