Castor oil isn't a new ingredient by any means: It dates back to the time of Cleopatra, queen of the Nile. But due to the beauty industry's new-ish fixation on natural and clean approaches to ingredients, it's made a regal reappearance — mainly in hair growth products. Instead of settling upset stomachs and sealing in night creams, some are using castor oil for eyelash growth, rather than serums.
The oil is a fatty acid that contains anti-inflammatory, antimicrobial, and moisturizing properties. Dr. Dominic Burg, Ph.D, chief scientist, hair biologist and microbiologist at évolis, says that castor oil contains ricinoleic acid as its main component. This acid “is thought to work by stimulating the receptor of a special molecule called prostaglandin E2 (PGE2),” Dr. Burg tells TZR.
But how does castor oil aid in hair growth — especially in eyelashes? While there's no conclusive evidence, there's a ton of anecdotal proof. “The theory is that PGE2 has a role in hair growth by stimulating hair follicles to enter the growth phase,” Dr. Burg explains. There is some evidence for this in hair cells grown in laboratories, but no real evidence in clinical studies on people, he notes. “So by stimulating the receptor for PGE2, castor oil may have a similar effect.”
With little scientific evidence to back up the claims, it’s hard to say that it affects hair growth definitively. But, it is beneficial to eyelashes because it contains both Omega-6 and Omega-9 which are essential fatty acids that can condition and strengthen eyelashes,” trichologist Bobby A. Spence says. Conditioned lashes stay hydrated which keeps them from shedding as much and also gives the appearance of fuller and thicker lashes — which can make you think that your lashes are growing.
Cosmetic chemist Ginger King also agrees that castor oil is for conditioning, not growth. She tells TZR that she doesn't see any scientific evidence for castor oil growing the lashes and notes that "there is no real efficacy, just moisturizing benefits only."
If you're still opting to test castor oil on your lashes, aim to place it at the base of the lash on the outside of the lash line, Dr. Burg says. If the oil accidentally gets into the eye, you may experience a little irritation, but this should pass quickly, he notes.
While there's still no real answer to settle the debate if castor oil will make your eyelashes grow, ahead, shop natural oils to help condition your lashes.