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

I know, I know: We're constantly bombarded with reports of miracle hair oils that promise to reinvigorate our hair, wipe out build-up for good, and generally change our hair forever. But before you write off castor oil as yet another beauty fad, consider that this ingredient has a centuries-long history that dates all the way back to ancient Egypt. Plus, it's backed by dermatologists and hair experts as an effective way of quenching dry strands and potentially stimulate healthy hair growth. Curious? We were, too. So we tapped the experts to get more intel.

What does castor oil do to hair?

If you happened to look at the molecular structure of castor oil, you'd see that it's a glycerol with a long-chain fatty acid. Why does that matter to you? Fatty acids are excellent at nourishing hair follicles, according to Atlanta-based dermatologist Tiffany L. Clay, M.D.. The outer layer of the hair shaft is covered in tessellating, scale-like structures called cuticles, and when the hair is damaged, those become flayed and flared, resulting in frizz and dullness. But hope is not lost! Clay points out that "castor oil can seal and allow the cuticle to lie flatter."

How should I apply castor oil to my hair?

To apply the oil, Clay recommends warming a small amount between your palms and smoothing it along the ends of your hair on a weekly basis. Just be sure you don't use too much. Castor oil is quite thick, so using too much can leave hair slick or greasy―some reports even suggest that the compound can lead to felting or matting. 

If you're not comfortable using pure castor oil for fear of overdoing it, there are a number of less intense options, including shampoos, conditioners, hair masks, and serums.

Our Favorite Castor Oil Hair Products

Will castor oil make your hair grow?

Yes and no. "There is some proposed benefit of castor oil with improving penetration of topicals and even hair growth," says Dhaval G. Bhanusali, M.D. a New York City-based dermatologist who specializes in hair loss. "That being said, I don't think the scientific evidence is there to make any sizable claims, particularly for stimulating new hairs."

If you think of your scalp like a garden, you'll agree that keeping a garden well-watered and fertilized will yield better tomatoes than one that's dusty and untended. So, yes, castor oil will keep your scalp hydrated and nourished, and the resulting hairs will be stronger, shinier, and healthier. But there will not be more of them, and that's an important distinction.

But the inefficacy of castor oil in stimulating new hair growth shouldn't leave you discouraged. "When it comes to hair loss, I can't stress enough how important it is to go see a board-certified dermatologist," says Bhanusali. "We now have so many new options and it's much easier to create a comprehensive plan for early hair loss than later in the game."

Our Favorite Castor Oil Shampoo and Conditioner