People have been using castor oil for their skin and hair for centuries in the US, but the old-school remedy has recently received some fresh attention—as in, more than a billion views on TikTok. This sudden surge in interest makes sense: The popularity of face oils and other “natural” skin care products has been steadily spreading over the last decade-ish, making simple ingredients all the more appealing.

Before we get into castor oil’s potential beauty benefits, though, we’d like to take this opportunity to note that “natural” is essentially a meaningless marketing term that the FDA hasn’t defined. And perhaps more to the point: Just because something’s natural, that doesn’t mean it’s good for you—or even safe.

Okay, now that we got that out of the way, what exactly can castor oil do for your skin? What about your hair and eyelashes? We asked dermatologists what you need to know about the sticky substance, including why (and how) to incorporate it into your routine.

What is castor oil?

Castor oil is a thick vegetable oil that’s extracted from the bean of the tropical castor plant (or ricinus communis, if you want to get horticultural). It contains several moisturizing fatty acids (including ricinoleic, linoleic, and stearic acid) that—when applied topically—can boost hydration and address certain skin conditions.² You can buy a bottle of plain ol’ castor oil at many health food and drugstores, but you can also find it in some personal care products and cosmetics, like lotions and lipstick.

Again, one of the major draws of castor oil is the fact that, in its 100% pure form, it’s a single-ingredient product, which, appeals to the growing number of consumers seeking “clean” skin care, Jill Waibel, MD, board-certified dermatologist and owner of Miami and Dermatology Laser Institute, tells SELF.³

What can castor oil do for your skin and hair?

Overall, limited research shows that the ricinoleic acid in castor oil may have antimicrobial and anti-inflammatory properties (which could, theoretically, be helpful for inflammatory conditions like eczema and psoriasis).^4 5 But we still need more data, Dr. Hollmig says, as these potential benefits have mainly been found in a lab test tube or via a computer-simulated model.

Test tube studies are a good starting point and help researchers know if they’re on the right path with a specific ingredient, but they’re a far cry from applying castor oil to a variety of people and measuring the results in a randomized controlled trial. In other words, “it’s difficult to draw conclusions on how influential these properties will be on our actual skin,” Dr. Hollmig explains. Still, there are some science-backed reasons to consider adding castor oil to your routine, like the following.

In the wintertime, both the cold, dry air outside and the hot, dry air indoors draw moisture out of your body (including your skin)—which is why you may notice that your complexion is flaky and dull, rather than smooth and dewy, in the colder months, Dr. Waibel says.As we mentioned above, castor oil is rich in fatty acids that may help counteract dry skin.⁶ And since plant oils are occlusive (meaning they create a barrier that prevents water from evaporating from your skin), Dr. Hollmig says, you can also try layering it on top of a moisturizer for an extra hydration boost.⁷ That said, castor oil isn’t your only option here: Dr. Hollmig notes that coconut oil, petrolatum (petroleum jelly), and mineral oil, for example, all seal in moisture in similar ways.

Castor oil is also rather thick, Annie Chiu, MD, a board-certified cosmetic and general dermatologist on faculty at Cedars-Sinai Medical Center, tells SELF. So when using it on your face or body, she recommends mixing it with a “carrier oil” to thin it out and make it easier to apply. Coconut, olive, and almond oil are all good choices. If your hands are particularly dry, Dr. Chiu also suggests combining castor oil with shea butter, applying the mixture before bed, and slipping on spa gloves to lock in hydration while you sleep. (You can also spread a thin layer on your lips to help heal cracks.)

You might have heard that castor oil can do incredible things for eyelash growth. Unfortunately, the science doesn’t bear out that claim—and any lush-lash effect is likely more of an illusion. However, the oil may create a healthier environment for eyelashes to grow by keeping them moisturized, Dr. Waibel says. There’s even some research indicating that it can help to manage conditions like blepharitis, an inflammatory eyelid issue that can make eyelashes fall out.⁸ If you decide to use castor oil on your lashes, apply it to your lash line with a small, clean makeup brush once per day, Dr. Waibel recommends. As with any new product, watch for signs of irritation (such as tenderness, redness, or itching) and stop using it if that happens.

As for castor oil benefits for hair, many families have used it for generations. “Growing up in a traditional Black household, we’d use castor oil often to moisturize our scalp,” Laura Scott, MD, a board-certified dermatologist and founder of Scott & Co. Skin in San Diego, tells SELF. “If you were dealing with hair loss, Jamaican black castor oil might be recommended by an aunt.”⁹

The time-honored oil’s collection of fatty acids, along with vitamin E, are really great at moisturizing the scalp, Dr. Scott explains. Plus the act of massaging the oil into your skin can increase blood flow to the hair follicles, which could theoretically help your strands grow thicker, she adds—though you’d have to do this consistently to reap any perks. (The act of “stretching” the hair follicles with your fingertips via massage may also be responsible for these potential benefits, research suggests.)¹⁰ Pro tip: Go for cold-pressed castor oil, which is thinner and easier to apply, Dr. Scott says.While the heavy oil may be great for hydrating the skin, it can also lead to buildup and trigger scalp acne along your hairline, Dr. Scott adds (more on that below). Your hair type matters here. If you have super tight, 4C curls that tend to soak up moisture, go ahead and use castor oil two to three times per week. People with fine, straight hair, however, should stick to once or twice per week max, according to Dr. Scott. Apply it an inch behind your hairline, massage it in like a deep-conditioning treatment, and wash it out after a few hours or the next morning, if you use it overnight, she says.

You can give this scalp massage routine a try if it’s a self-care activity you enjoy, but don’t expect miracles: A systematic review in the Journal of Drugs in Dermatology concluded that castor oil can improve luster—but there isn’t yet evidence that it stimulates hair growth.¹¹ “I’d love to see better studies out there on this,” Dr. Scott says. “The data we have right now doesn’t support castor oil as an effective hair growth treatment, but that doesn’t mean it’s not true.”

But there are some potential drawbacks too.

If you deal with pimples or oily skin, you might want to think twice before slathering on castor oil. Yes, it may have antibacterial properties, which in theory could help minimize zits, but, again, it’s also very thick, Dr. Hollmig notes: “Some patients have pores prone to clogging by occlusive substances like castor oil, which may worsen acne.” In other words, if you’re acne prone, tread carefully. Even better: Talk to a dermatologist first, they can help guide you in using castor oil in the best way for your skin type—or suggest alternative products.

While the dermatologists we talked to say that castor oil is generally tolerated well, just like with any ingredient, an allergic reaction is possible. If you notice redness, itchiness, peeling, flakiness, rashes, or a burning scalp, stop using it.

Oh, and we can’t let you go without issuing this warning: While some people swallow castor oil to relieve constipation—it is FDA-approved as a stimulant laxative—don’t expect that a swig will make your skin glow.¹² You may end up dashing to the toilet with dehydrating diarrhea, which won’t do your skin any favors, Dr. Waibel says.

The bottom line on the potential beauty benefits of castor oil

It can be an effective moisturizer for your skin and hair, especially if you need a fast dryness fix. Just know that there isn’t a lot of scientific evidence backing up all the promises out there, including hair and eyelash growth. Plus the thick oil can clog pores and cause acne if you break out easily. That’s why Dr. Chiu recommends checking in with a dermatologist before you start slathering it all over yourself if you can—#skintok has a lot of big ideas, but it isn’t always right.

1. JAMA Dermatology, Natural Does Not Mean Safe—The Dirt on Clean Beauty Products
2. The Natural Products Journal, Phytochemical, Pharmacognostic, and Pharmacological Aspects of Ricinus Communis Seed Oil: An Overview
3. Research and Markets, Global Clean Beauty Market (by Product Type, Distribution Channel, & Region): Insights and Forecast with Potential Impact of COVID-19 (2023-2028)
4. IOP Conference Series, Physicochemical Properties and Antibacterial Activity of Castor Oil and Its Derivatives
5. International Journal of Pharmaceutics, Anti-inflammatory Effects of a Novel Ricinoleic Acid Poloxamer Gel System for Transdermal Delivery
6. Molecules, Bioactive-Based Cosmeceuticals: An Update on Emerging Trends
7. International Journal of Molecular Sciences, Anti-Inflammatory and Skin Barrier Repair Effects of Topical Application of Some Plant Oils
8. Clinical and Experimental Optometry, Therapeutic Potential of Castor Oil in Managing Blepharitis, Meibomian Gland Dysfunction and Dry Eye.
9. International Journal of Dermatology, Commonly used hair oils in the Black community: a narrative review in their use to treat androgenic alopecia
10. Eplasty, Standardized Scalp Massage Results in Increased Hair Thickness by Inducing Stretching Forces to Dermal Papilla Cells in the Subcutaneous Tissue
11. Journal of Drugs in Dermatology, Coconut, Castor, and Argan Oil for Hair in Skin of Color Patients: A Systematic Review
12. StatPearls, Castor Oil