Does Using Castor Oil for Hair Growth Actually Work?

A dermatologist shares whether there's really a link between castor oil and hair growth.

Hair Health Hotline: Castor Oil
Photo: Getty Images

Hair Health Hotline is your direct access to dermatologists, trichologists, hairstylists, and other beauty pros. Each story in this series tackles a common hair or scalp concern and offers science-backed solutions to care for your strands.

Castor oil has emerged as one of the most popular solutions for promoting hair growth, and its appeal is easily explained. It's inexpensive, readily available at drugstores and supermarkets, and has won over amateur DIY beauty mixologists and celebrities alike. Even Cleopatra reportedly used castor oil to maintain healthy hair growth and strong strands, according to an article published in the Journal of Drugs In Dermatology.

Of course, castor oil's longtime popularity doesn't mean much if the oil doesn't live up to all the hype. Before you decide whether to stock up, hear from Kellie Reed, M.D., F.A.A.D., a board-certified dermatologist at Westlake Dermatology in Austin, Texas, about whether using castor oil for hair growth can produce results.

Q: I'm experiencing hair loss and I keep seeing social media posts about castor oil. Is using castor oil for hair growth actually effective?

A: The possible link between castor oil and hair growth isn't backed by research, according to Dr. Reed.

If you're unfamiliar, castor oil is derived from the seeds of the castor bean plant, as noted in an article in the International Journal of Trichology. Maybe you've heard of castor in another context: the oil can also be taken orally as a laxative.

As mentioned, there isn't scientific evidence that applying castor oil can impact hair growth, but there are some theories as to why people have reported that it can, says Dr. Reed. "In theory, it's thought that [castor oil] could help because of what it does on the scalp," she says. "It has a high content of [a fatty acid called] ricinoleic acid, and it's thought to help improve blood circulation in the scalp." Boosting circulation can deliver oxygen and nutrients to hair follicles which can enable hair growth. "So it's thought that that could lead to hair growth, but this is all speculative," says Dr. Reed.

When applied to the skin, ricinoleic acid may also inhibit the enzyme prostaglandin D2 synthase, according to the International Journal of Trichology article. Elevated levels of the enzyme seem to suppresshair growth, according to an article in Science Translational Medicine.

In addition, castor oil also has moisturizing, antibacterial, and anti-fungal properties thanks to the ricinoleic acid, making it beneficial to both your scalp and strands, according to the International Journal of Trichology article.

"Patients will say, anecdotally for them [castor oil] has helped, but we just don't have the studies to as dermatologists say, 'yes, this is a great product for hair growth,'" says Dr. Reed. "...There are other products that are known to absolutely promote hair growth [such as] Minoxidil, otherwise known [by the brand name] Rogaine," says Dr. Reed. "If that is not the approach that one wants to take, and they want to take a more natural approach, it's reasonable to look at castor oil." However, castor oil isn't even the most promising natural approach, as rosemary oil has data backing up its possible hair growth-boosting effects, she adds.

Hair Health Hotline: Castor Oil
Courtesy of Kellie Reed

Caveats to Keep In Mind If You Want to Try Castor Oil

If you decide you're interested in experimenting with castor oil for hair growth, you don't have much to lose by trying it. You can snag a bottle for under $10, and castor oil is equally suited to all hair types, according to Dr. Reed. That said, "don't use castor oil in pregnancy, just because there is anecdotal evidence that castor oil could induce delivery" when taken orally, she says.

Another thing to be aware of: "[Castor oil] can be a bit thick and so it can clog pores, especially on the forehead, and clogged pores could potentially lead to acne," says Dr. Reed.It's unclear whether castor oil can trigger acne or folliculitis (i.e. inflammation of follicles) on the scalp, but the oil's antibacterial and antifungal properties might actually help counter those issues, she says. Try using castor on a small area before applying it to your entire scalp, she advises. "I haven't seen issues, but as with any product you may want to put it on your scalp and watch for any irritation or any acne or any other sort of adverse event," says Dr. Reed.

Castor oil is also popular as a one-ingredient eyelash serum — eyelashes are hairs, after all — but you should proceed with caution because of the oil's tendency to clog pores. "I'd always recommend speaking with your ophthalmologist before you put something near your eye like that," says Dr. Reed. "It could be possible to trigger a chalazion or other issues." (A chalazion is a bump caused by the blockage of an oil gland in your eyelid, according to the American Academy of Ophthalmology.)

How to Select and Use the Best Castor Oil for Hair Growth

You can use pure castor oil or a product containing castor oil — the distinction is a matter of preference, says Dr. Reed. When it comes to pure castor oil, she suggests trying Jamaican black castor oil for hair growth or reaching for cold-pressed castor oil if you plan on applying the oil to the strands of your hair. "It is thought that cold-pressed castor oil has better quality oil than other types due to the oil extraction method, but no research has confirmed this," she says. "The cold-pressed oil may be preferred for finer hair." As for black castor oil, it's "anecdotally thought to be better for hair growth specifically, although no research has proven this," says Dr. Reed. "It may also be preferred for those with dense or coarse hair."

Whether you're using a multi-ingredient product or pure black castor oil for hair growth, you want to make sure to apply it directly to your scalp. "That's where it's affecting the dermal papillae, which is the root of your hair follicle fuel that helps with hair growth," says Dr. Reed. To use an oil for hair growth, you can apply the oil to your scalp — no need to dilute castor oil beforehand since it's not an essential oil — once per week after washing your hair, as Shape previously reported.

To use castor oil to moisturize your strands and prevent breakage rather than for hair growth, simply apply a very minimal amount (read: a pea-sized drop or two) to the lengths of your hair, suggests Dr. Reed.

If you're hoping to combat hair loss or thinning with a science-backed, extensively-researched ingredient, shift your attention elsewhere. But if you've heard through the grapevine that castor oil is a game-changer for hair growth and love a good DIY beauty project, feel free to give it a go.

Have a hair health question you want answered? Send your Q to for a chance to have it featured in a future installment of Hair Health Hotline.

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