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Castor Oil for Hair 101: The Benefits, Risks, and How Exactly to Use It

Meet your new favorite ingredient.

castor oil
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If you do even the tiniest bit of digging around the internet for ways to get longer, thicker hair, you'll def see tips about castor oil for hair growth come up. This hair oil isn't the slightest bit new (castor oil is a centuries-old hair treatment and a longtime favorite Jamaican beauty remedy), and it's one of those ingredients that's solidified its status as a staple in many haircare routines. And it makes sense why: Castor oil is easy to apply, affordable, accessible, and surprisingly beneficial for your hair and scalp.

That said, even the very best products and ingredients have their limits. Although (spoiler alert!) castor oil might not be the hair-growth miracle you're searching for, it still has its place and deserves a spot in your hair regimen. We gathered all the best advice and insight from dermatologists, trichologists, hairstylists, and even an ophthalmologist and eyelash expert to find out the best ways to use castor oil for the most benefit and figure out if it actually can help you grow longer hair. Wanna know what we learned? Keep scrolling.

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What are the benefits of castor oil for hair?

Castor oil is a vegetable oil pressed from castor beans, and it's been around for centuries. It’s usually colorless, although you’ve likely seen yellow or black versions on Amazon or at your local Ulta. Jamaican black castor oil is one of the more popular variations (and a favorite of Nastasha Burrell, licensed cosmetologist and hair expert). It has a thicker consistency because it’s boiled with ash, which gives it a warm, roasted scent. Castor oil itself is loaded with vitamin E, fatty acids, and minerals, says Hadley King, MD, dermatologist in NYC, and is naturally emollient, making it an ideal ingredient for ultra-hydrating conditioners and masks.

It’s also a super-popular option for treating irritated scalps, excess oil, and dandruff, thanks to the fact that “castor oil is not only anti-inflammatory and anti-microbial, but it also helps maintain moisture in the skin,” says Michelle Blaisure, BosleyMD trichologist.

Is castor oil really good for hair growth?

The good news: Castor oil is an affordable treatment if you’re looking to add shine, smooth flyaways, and condition your hair, says hairstylist Courtney Foster. The not-so-good news: Even though there are plenty of stories around castor oil and hair growth, there aren’t any studies or scientific evidence that proves castor oil will actually grow your hair. I know, I know—the truth hurts.

But even though there's no concrete evidence that directly links castor oil and hair growth, all hope isn't lost. Hear me out: The ricinoleic acid in castor oil helps lock in moisture while promoting a clean and healthy scalp—all of which are essential to hair growth. So if growing your hair super long is the goal, there’s no reason why you shouldn’t be using castor oil to set yourself up for success.

How long does castor oil take to work?

It's important to keep in mind that hair growth doesn’t happen overnight—regardless of what products or treatments you’re using. Hair only grows half an inch every month, as previously explained by hairstylist and brand educator for Creme of Nature Patricia Williams in a Cosmo article. And that growth only happens if your hair is already in a healthy state with minimal split ends and damage.

So, how often should you use castor oil to reap the full benefits? “There is no standard as far as how often you should use castor oil, but I’d recommend one to two times a week for at least three months, as that’s typically how long before you’ll see new hair coming in,” says Blaisure. And hey, if after three months you still aren’t seeing a significant change, at the very least, you’ll have hydrated, shiny-as-hell hair.

Is castor oil good for eyelashes and eyebrows?

As long as you’re using caution (i.e., you aren’t putting it directly in your eyes), then yes, castor oil is safe to use on your lashes and brows. Again, there’s no guarantee that castor oil will make your hair grow faster, but it can act as a great lash conditioning serum. “Castor oil moisturizes your eyelashes and can make them appear thicker and have more luster,” Ilyse Haberman, MD, an ophthalmologist at NYU Langone Health previously explained in a Cosmo article. “It’s also possible that it can help prevent lash breakage which, in turn, can lead to healthier growth.”

One thing to keep in mind: dermatologist Lily Talakoub, MD, founder of Derm to Door, says that castor oil is known to clog pores. “The skin around your eyebrows and eyelids is thin and prone to clogging, and using castor oil can exacerbate milia, blackheads, and acne,” she explains. That goes for all skin types, btw, not just folks who are oily or acne-prone, so it's best to approach with caution (and it's never a bad idea to do a patch test on your neck or check in with your dermatologist before you try it out on your face).

What are the risks of using castor oil on the hair?

Although castor oil is generally pretty safe, it's worth noting that it can cause irritation. Make sure you kick things off with a patch test (just like with your eyebrows and eyelashes) and don't be afraid to run it by your dermatologist—especially if you have a sensitive scalp. Dr. Talakoub stresses the importance of keeping castor oil off of your hairline (again, it's known to clog pores) and to use extra caution when applying it before bedtime, since the oil can transfer from your pillowcase to your face, leading to potential breakouts.

How do you apply castor oil to hair?

There's no right or wrong way to apply castor oil to your hair—some people like to leave it on overnight while others like to massage it into their scalp. The best method for you totally depends on your hair type and concerns. As a reminder, Jamaican black castor oil is on the thicker side, so it’s best for anyone with dense or coarse hair, whereas regular cold-pressed castor oil is great for finer hair types.

For a scalp treatment:

Burrell loves using castor oil for a scalp massage but don't forget the ends, too. Burrell suggests working the product throughout the hair strands as well as the scalp for 5 to 10 minutes. You could also try sitting under a hair steamer for 20 to 30 minutes to help the oil really penetrate your scalp, and then keep it in until your next wash day.

For a moisturizing pre-poo treatment:

Burrell says for the best results, mix castor oil with carrier oils, such as jojoba or coconut oil, to dilute it. As previously shared with Cosmo, trichologist Bridgette Hill also loves mixing castor oil with olive oil (another carrier oil) as a hair treatment, and this combo works great for an intensely moisturizing pre-poo on dry hair.

You could also try mixing a few drops of castor oil into your conditioner and spreading it through damp hair for at least 30 minutes before washing (a tip Jasmine "Jazzee” Santiago, hairstylist and texture expert, has previously shared with Cosmo).

For overnight deep conditioning:

Coat your hair with castor oil and slap on a shower cap before going to bed. When you wake up, gently comb your hair and follow with shampoo and conditioner. Note: Some people opt for a double shampoo to help rinse the castor oil all the way out.

For protective hairstyles:

Combine castor oil with olive, grapeseed, coconut, and vitamin E oils in an applicator bottle for a gentle and antioxidant-rich scalp treatment. Peep this tutorial to see how it's done.

For eyelashes and eyebrows:

Before bed, lightly dip a clean spoolie brush or Q-tip in the castor oil (a small amount will do) and carefully swipe the product along your lash line without getting any product in your eye. Wash and remove the product in the morning.

Bonus tip: Castor oil works great at removing eyelash extensions, as Dionne Phillips, celebrity eyelash extension expert of D’Lashes, has previously explained to Cosmo. Use the same technique as above to simultaneously treat your own lashes and loosen the adhesive to remove the extensions.

    The final word

    While the scientific data is lacking on castor oil and hair growth, the cost-friendly oil can do wonders for your hair and scalp, which, obvi, is essential for healthy, long hair. And remember to be cautious of everyday behaviors that can cause hair loss and breakage in general, like wearing super-tight hairstyles (think: braids and tight ponytails), brushing too hard, and using excessive heat styling. Because even castor oil, as great as it is, can only do so much.

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