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Hair oils are believed to have a variety of benefits. They can moisturize your scalp and hair follicles, promote hair growth, and reduce the chances of hair falling out. But that isn’t all—some hair oils even have therapeutic benefits, helping alleviate irritated scalp skin and reducing flaky dandruff. Basically, they’ll make your hair look healthier and stronger overall.
Meet the experts: Brendan Camp, MD, FAAD, is a board-certified dermatologist at MDCS Dermatology in New York City. Ramya Garlapati, MD, is a Los Angeles-based board-certified dermatologist, co-founder of Skin Medicinals, and skincare expert. Lauren Penzi, MD, is a board-certified dermatologist specializing in medical and cosmetic dermatology on Long Island.
Wondering how hair oils can accomplish so much? Well for starters, they help kick sebum, your skin’s natural oil, into gear. “Sebum is secreted by sebaceous glands attached to hair follicles,” says says Brendan Camp, MD, FAAD, board-certified dermatologist at MDCS Dermatology in New York City. “By coating the hair shaft with oil, sebum helps soften and smooth hair and strengthens it to prevent breakage.”
If you're new to using hair oils, rosemary oil is a pretty good place to start. As you may have seen on your TikTok FYP, it has many benefits for treating the scalp and hair, and this is one social media craze that actually has research to support its claims, says Ramya Garlapati, MD.
Ahead, learn everything you need to know about using rosemary oil for hair growth, including how to use it and its potential side effects.
What is rosemary oil?
This oil is extracted from the Rosemarinus officinalis—or rosemary—plant, a fragrant evergreen shrub native to the Mediterranean region that sprouts blue or whitish flowers. You're probably most familiar with this plant as a garnish for some of your favorite savory dishes—it has an earthy taste and many powerful compounds that provide myriad health benefits.
How rosemary oil benefits the hair
Promotes hair growth: “Rosemary has been shown to have significant antimicrobial, anti-inflammatory, anti-oxidant, anti-apoptotic, anti-tumorigenic, antinociceptive, and neuroprotective properties,” says board-certified dermatologist Dr. Lauren Penzi, MD. So, it can promote hair growth and prevent breakage by coating the hair with fortifying oils.
In a 1998 randomized, controlled, double-blind study of 86 patients with alopecia areata, it was found that an aromatherapy essential oil blend of thyme, rosemary, lavender and cedarwood was way more effective than the placebo. Basically, rosemary oil has been found to be equally as effective as topical minoxidil, which treats androgenic alopecia, but it’s safe for all hair loss patients.
Reduces scalp irritation: It can also reduce scalp irritation from issues like dandruff because “it is thought to be a vasodilator, meaning it increases blood flow in scalp skin,” says Dr. Camp. “This improved circulation is thought to help maintain hair in the growing phase and prevent shedding.”
If you're expecting to wake up the morning after using this oil with noticeable length or fullness, you're bound to be disappointed. Nothing works overnight and progress can be slow—but don't give up. "Keep in mind that hair changes in general are slow, and it will take a minimum of three to six months before seeing any noticeable results,” Dr. Penzi adds.
How rosemary oil promotes hair growth
Rosemary oil helps hair grow by “blocking the effects of DHT, which is a type of testosterone that is normally responsible for shrinking hair follicles that can lead to hair loss,” says Dr. Garlapati. “It increases blood flow to hair follicles, which increases the delivery of oxygen and nutrients promoting hair growth.”
Who can use rosemary oil?
Anyone can use rosemary oil to treat their scalp, but it’s especially helpful for those experiencing dandruff, hair shedding, thinning, breakage, or loss—in specific, “those who may want to take a more natural approach to hair loss management or would like to add rosemary oil as a supplemental treatment to their regimen,” says Dr. Garlapati.
Just remember to discuss the cause of your hair loss with a dermatologist before trying an at-home treatment like rosemary oil. “Others with more sensitive skin may want to use rosemary oil with caution to avoid skin irritation,” Dr. Camp says.
What are the side effects of using rosemary oil on hair?
It’s safe for all hair types, even color-treated hair, says Dr. Garlapati. “There is little to no risk of any side effects,” Dr. Penzi adds.
However, Dr. Penzi points out that essential oils have biologically active components and may be toxic. “Oils with high concentrations of aldehydes and phenols may cause skin irritation,” she says. “Essential oils containing high concentrations of ketones should be used cautiously in pregnant women and infants.”
Rosemary oil can also cause allergic or irritant contact dermatitis, so be on the lookout if you’re noticing anything out of the ordinary going on with your scalp or hair. If you experience any irritation, stop using it.
Even if you're not seeing any negative side effects, be wary of how often you’re using it. “When used in excess, rosemary oil can make thinner hair look greasy and feel weighted,” Dr. Camp notes.
Can I apply rosemary oil directly to my scalp?
Rosemary oil can be used as a stand-alone treatment, and where you apply it should depend on what you’re struggling with: “When used to treat hair loss, it should be applied directly to the scalp," says Dr. Camp. "When used for treating damaged hair, it should be applied to the hair.” Take a few drops and massage it right into your scalp to promote blood flow.
6 Rosemary Hair Products We Love
Mielle Organics Rosemary Mint Scalp & Hair Strengthening Oil
Pacifica Beauty Rosemary Apple Cider Scalp Detox Tonic
Camille Rose Rosemary Water Daily Strengthening Mist
L’Oréal Paris EverStrong Thickening Sulfate Free Shampoo and Conditioner Kit
How to use rosemary oil for hair
Dr. Garlapati recommends leaving it on for at least ten minutes, and using it daily or a few times a week, and Dr. Penzi advises applying at night and washing it out in the morning.
While applying the pure oil will probably be more effective, you can also put some drops of rosemary oil to your shampoo and let it sit on your scalp for a few minutes to see if the benefits apply there too.
It can also be added to a “carrier oil, like coconut or olive oil, to dilute it,” adds Dr. Camp. Also, BTW: there aren’t any known ingredients that interfere with rosemary oil, so Dr. Penzi says you shouldn't worry about using it alongside other products that might be in your haircare routine.
And if you don't feel like using a bottle of essential oil from your local health food store, you can pick up one of these hair products that contain rosemary oil too. Happy moisturizing.
Addison Aloian (she/her) is the assistant love & life editor at Women’s Health. Outside of topics related to lifestyle, relationships, and dating, she also loves covering fitness and style. In her free time, she enjoys lifting weights at the gym, reading mystery and romance novels, watching (and critiquing!) the latest movies that have garnered Oscars buzz, and wandering around the West Village in New York City. In addition to Women's Health, her work has also appeared in Allure, StyleCaster, L'Officiel USA, V Magazine, VMAN, and more.
Brian Underwood is the beauty director at Women’s Health. He is an award-winning journalist with more than 15 years of experience covering beauty and lifestyle for several national media outlets and previously served as beauty and wellness director at Oprah Daily. His work has appeared in Woman’s Day, Life & Style Weekly, Good Housekeeping, and many more. He also serves as a member of the Skin Cancer Foundation’s gala committee and lives in New York City with his daughter.
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