Additionally, the smaller studies above used a combination of essential oils in their experiments, so it’s difficult to know what role rosemary, specifically, played in the results. The research also looked at the effects of these oils when applied directly to the scalp—not when mixed with over-the-counter shampoos, conditioners, or serums with varying formulations. So just because a hair product claims to “voluminize” or “lengthen” because it contains rosemary oil, that doesn’t mean it will work (although it may smell nice!).
Another important caveat: Although rosemary oil led to the same hair growth as 2% minoxidil in the first 2015 clinical trial mentioned above, the results were not what visibly impressive for any treatment. (We’re talking about a subtly noticeable increase in the number of filled strands compared to a suddenly full head of hair). It is standard practice for dermatologists to prescribe a higher concentration of Rogaine, Carmem Castilla, MDboard-certified dermatologist and associate clinical professor at Icahn School of Medicine at Mount Sinai in New York City, tells SELF, “We typically recommend 5% minoxidil, and when you compare 2% and 5%, the latter is significantly more effective.”
How (and when) rosemary oil could theoretically help support hair growth
Right now, there isn’t enough evidence to suggest that rosemary oil can magically fix sparse blemishes or stop a receding hairline. Even the experts we spoke to aren’t sure how this it could work – but they have some theories.
Rosemary oil (and specifically the carnosic acid and carnosol contained in it) has anti-inflammatory and antioxidant properties, which dermatists believe can help. stimulate blood flow to hair follicles, Lindsey Zubritsky, MD, a board-certified dermatologist at Premier Dermatology and Skin Cancer Center in Ocean Springs, Mississippi, tells SELF. Simply massaging the scalp (with or without rosemary oil) can also play a role in increasing circulation, research shows. “Increased blood flow equals more nutrients to the scalp, which can help with hair growth, strength, and thickness,” explains Dr.
Another theory, she says, revolves around rosemary oil’s anti-inflammatory and antimicrobial properties, which could help maintain a “healthy scalp environment.” (An inflamed scalp can weaken hair follicles and potentially result in hair loss.)
Again, there’s no hard science to fully support this, but even if routine scalp oil application has these effects, all three experts warn that it won’t help. all types of thinning or baldness. “There are actually various types of alopecia and hair loss,” explains Dr. Cameron – each with different causes that require personalized treatments.
To look for shows that people with androgenetic alopecia, for example, may have better luck with topical solutions like minoxidil compared to people whose shedding is triggered by an autoimmune disorder or other underlying condition. The latter would require interventions that address the root cause of the health problem. (In case of alopecia areatasteroid injections are a common treatment.)
Are there any risks to be aware of when using rosemary oil on your scalp and hair?
If you still want to try it, there aren’t many unpleasant side effects to worry about. However, “I would be careful if you have a history of Allergic reactions or scalp sensitivity due to conditions such as psoriasis or eczema,” says Dr. Zubritsky, as rosemary oil can sometimes cause contact dermatitis, an unpleasant rash that occurs when the skin comes into direct contact with certain irritants or allergens, such as essential oils or added fragrances. (That’s why you should always patch test apply any new hair product to a small area of skin before applying it to your entire head.)