From thickening shampoos to retinol (yes, retinol), the topic of hair growth has been taking over TikTok for a while now, with countless solutions now sitting under the hashtag. Rosemary oil is the one of the buzziest topics in the lineup of viral ingredients, and TikTokers are dubbing it a one-way ticket to growing your hair naturally.
Racking up over 2.8 billion views and counting, there's a good reason why the hashtag #rosemaryoil is trending: Like so many of the hyped up ingredients that came before it, a collective concern over hair loss (75% of British women say they're worried about hair loss, according to hair brand Philip Kingsley) is fuelling the demand. And what's more appealing than a simple, natural remedy?
Here's what the experts think.
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What is rosemary oil?
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What are the benefits of rosemary oil for hair?
Rosemary oil has a host of potential benefits. "It contains compounds which have been shown to have some anti-inflammatory, antimicrobial and antioxidant activities," explains Dr Sharon Wong, consultant dermatologist and hair specialist. All such properties reduce scalp irritation, while antioxidants specifically help protect your hair from external aggressors such as pollution. Put simply, this tends to equal stronger strands and a healthier scalp.
Is rosemary oil good for hair growth?
There has been some data that suggests rosemary oil could be good for hair growth, with two specific studies that point to its potential. "A study in 2015 compared the effects of rosemary oil versus 2% minoxidil [a topical medication] for the treatment of androgenetic alopecia [male and female pattern hair loss] and, after six months, found a similar increase in hair counts with both treatments," says Passam. Another study found that rosemary [essential] oil was an effective treatment for the patchy hair loss condition known as alopecia areata.
Though promising, these studies are small and the scientific research still preliminary. To add, the data is directed towards genetic hair loss (androgenetic alopecia) as opposed to analysing specific types. Pawlus adds that rosemary oil has a number of beneficial compounds, but these studies speak exclusively of the essential oil, which is "the volatile, aromatic component of plants [what you smell], which excludes some of rosemary's powerful antioxidants".
The issue? The quality of the oil can vary. "It depends on many factors including the growth conditions of the plant, the quality of the plant collected and how it was handled prior to extraction," says Pawlus.
Is it safe to use rosemary oil on your hair and scalp?
The experts say that, in theory, people with all hair types can use rosemary oil but some may want to proceed with caution. "Although natural, as with all plant extracts and botanicals, rosemary oil extracts and the raw material itself can potentially cause skin irritation and allergic contact dermatitis in some people," explains Dr Wong.
A possible catalyst for irritation is when using the oil alone. Despite what the TikTok videos might suggest, pure rosemary essential oil (and essential oils in general) is very potent and could cause scalp irritation. Worse yet, it might have the opposite of the intended effect. "Maintaining a healthy scalp plays a fundamental role in supporting healthy hair growth by providing conditions to optimise the function of the hair follicle," adds Dr Wong. "There are many examples in which an unhealthy scalp can lead to increased hair loss such as eczema, psoriasis, fungal infections or yeast overgrowth."
To that end, if you are going to use rosemary oil, make sure you're diluting it with another oil-based product and massaging it into your scalp, says Gaboardi. "I recommend mixing four or five drops with a teaspoon of oil, like coconut oil. You can then massage it evenly into your scalp." It is also said that the massaging action might be the catalyst for stimulating hair growth. "Scalp massaging can help increase hair thickness by stretching the cells of hair follicles, which then stimulates the follicles to produce thicker hair," says Gaboardi. Never apply rosemary oil to inflamed or broken skin, adds Passam.
How do you use rosemary oil for hair growth?
Aside from diluting it, not all rosemary oil formulas are created equal. Though sceptical about using rosemary oil as a hair growth treatment altogether, Passam suggests it's best applied as a leave-in product so that it has a greater chance of exerting its effects. "I would always recommend using rosemary oil in conjunction with other products [such as shampoos and serums] that support hair growth," adds Gaboardi, who says a balanced diet and supplementation are key.
Though plenty of new videos are surfacing to set the record straight, the misinformation that's being bandied about on TikTok is exactly what's causing concern among experts. Lack of education aside, many don't look at the root of the problem. "As a trichologist, my main concern would be that people may follow these trends when they would be better served finding out the reason for their hair loss and addressing this under the guidance of a specialist," says Passam. "Some types of hair loss are progressive so seeking appropriate advice early is likely to lead to better outcomes," she adds.
This isn't to say that rosemary oil doesn't have a place in your haircare routine, but more research is needed to understand whether it can really promote hair growth and density. For now, quality control and education is your best bet to determine whether you might want to try it out for yourself.
This article was originally published in February 2023 and has since been updated.