Will Castor Oil Actually Help Your Hair Grow? We Investigate

3 different castor hair oils

Getty Images / Graphic by Cristina Cianci

For years, the beauty industry has collectively touted the benefits of drenching our strands in basically every kind of oil you can find at your local supermarket. Coconut, olive, black seed (Kim Kardashian West's personal favorite), jojoba, and even more delicate essential oil offerings like rosemary, lavender, cedarwood, lemongrass, and peppermint have all been praised, but there's another oil that has been raising many an eyebrow in terms of its hair-growing prowess: castor oil.

Many people (Byrdie editors included) have experienced impressive results after applying castor oil to their brows with the goal of increasing hair growth. Its skin- and irritation-healing benefits can be cited back to ancient Egyptian society. So shouldn't the age-old remedy work the same type of magic on the tops of our heads? Here at Byrdie, it's our job to take hair health and our never-ending quest for luminous, shiny, growth-happy strands seriously. So we wanted to dig a little deeper into castor oil and all its glossy potential. Ahead, you'll find everything you ever wanted to know about castor oil for hair, and whether or not experts think it can actually make your hair grow faster.

5 Ways Castor Oil Promotes Better Hair Health
Grace Kim/BYRDIE

The Pros

Castor Oil (16oz)
Sky Organics Castor Oil $15

According to industry-leading dermatologist Rachel Nazarian, MD, of Schweiger Dermatology Group in NYC, castor oil can in fact be useful in certain cases of hair loss. A big fan of castor oil in general, she explained to us that unlike most other oils, which can veer mostly fatty, castor oil has a nutritional makeup composed of a powerful mix of proteins, vitamins, fatty acids, and antioxidants (aka the internal workings of all the buzziest hair supplements on the market). Thus, it comes as no surprise the oil is a wonderful way to nurture the scalp and fragile hair follicles while simultaneously encouraging healthier, faster hair growth. For this reason, castor oil has increasingly become a key ingredient in hair products.

Nazarian says that while the oil is a known irritant for many people, strategically applying a very small amount to your scalp or eyebrows may help to induce hair regrowth through a specific, localized region. That said, since it's an oil, a little will go a long way. Everything in moderation—don't go and dump an entire bottle of the stuff over your head. "As always, it's best to be cautious. You want to avoid overdoing it or getting it in your eyes and/or other sensitive areas," Nazarian warns.

"Studies have shown castor oil to be an effective and gentle method of cleansing your skin," Nazarian explains. "Because it's polarized, the castor oil actually attracts dirt and effectively cleanses the skin." This and its high content of ricinoleic acid may help improve blood circulation at your scalp, which results in nutrition for the hair follicles, stronger strands, and less breakage. Additionally, castor oil is a humectant, which essentially means it's an excellent vehicle for locking in moisture and shine. And as we know, moisturized (aka not dry, damaged, and split-prone) hair is far more likely to grow at an expedited, healthier rate.

In addition to its efficacy for your scalp, Nazarian tells us castor oil is thought to enhance and increase the absorption of other products. If incorporated into your normal hair ritual, your other products might actually penetrate more effectively, which will only do your hair's health and growth ambition a favor in the long run. After all, a residue-filled scalp does not a gleaming, Rapunzel-esque mane make.

If incorporated into your normal hair ritual, your other products might actually penetrate more effectively, which will only do your hair's health and growth ambition a favor in the long run.

But ultimately, what you need to know about castor oil is that a clean and healthy scalp is what will be the determining factor in regards to hair growth—not necessarily the castor oil itself.

The Cons

Lavender Castor Oil
Heritage Store Lavender Castor Oil $12

Now for the bad news: some experts very strongly believe there is no correlation between castor oil and hair growth. They acknowledge that while the stuff may help in the way of conditioning, the idea that it will increase hair growth is completely anecdotal. Not to mention, some people have even experienced hair fallout after using the stuff. Eek.

"Castor oil will not grow hair," cosmetic chemist and author Perry Romanowski told Allure earlier this year. "There is no evidence for it and no scientific theory supporting that it would work, so yes, it's a total myth." However, the publication also did point out that Romanowski said castor oil won't damage the hair, and may have some of those aforementioned conditioning perks that could help improve our hair fibers' flexibility.

In pursuit of a second opinion, Allure reached out to Adam Friedman, a program director at The George Washington University School of Medicine and Health Sciences, who wholeheartedly seconded Romanowski's blunt words. "While it does have antimicrobial properties which may be useful in terms of fighting off bacterial or fungal overgrowth on the scalp that can lead to hair-damaging inflammation, there is zero evidence [showing] it is helpful for hair growth," he told them. In fact, as Nazarian did as well, he points out that some people can find the oil irritating or even allergenic, which can invite bothersome and detrimental inflammation.

So, what to do? If you're seeking hair growth (40% of people struggling with hair loss are women, after all), the first and most helpful thing to do is pay your dermatologist a visit. That said, experts seem to agree the oil is safe enough to cautiously experiment with at home. Start out with a patch test, keep expectations realistic and heed their advice of using a small amount during application, to ensure you don't experience any adverse reactions. It's also often recommended you don't use it more than once a week. Warm the oil in your palms before working it through the roots of your hair, and brushing it out towards the ends. Leave it in for 15-20 minutes minimum, and then shampoo it out of your hair (it likely won't come out easy, so don't get discouraged.) You can wet your hair beforehand in order to make the oil soak in more, but some people don't need that. It's really up to you.

Ed. note: If you don't like how that feels or just want something more advanced, you can try an at-home recipe, like this one from nutritionist Katie Stewart that uses castor oil; avocado, jojoba, or olive oil.

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