We've investigated the hair-growing prowess of castor oil, and what we discovered was that hair and skin experts praise the oil for its mixture of proteins, vitamins, fatty acids, and antioxidants to nourish hair follicles and potentially prevent pollutants from inhibiting growth. But castor oil's benefits seemed to end there.
Taking that into account, one would assume that castor oil also wouldn't improve eyelash growth. But in the name of doing our due beauty diligence, we asked hair and skincare experts Dominic Burg and Dr. Rahi for their thoughts.
Meet the Expert
The Benefits of Castor Oil
"Castor oil has been used in beauty and skincare for its skin health benefits from reducing redness, inflammation, antimicrobial benefits (great for acne-prone skin) and boosting hydration," says Rahi. "When it comes to hair and lash health, there is no scientific evidence pointing to castor oil enhancing the length or growth of lashes. That being said, there are some benefits to offer moisture and conditioning benefits, which can aid with preventing lash breakage."
"While there is no solid clinical scientific evidence that this is the case, there may be some science behind the claims," adds Burg. "Castor oil contains ricinoleic acid as its main component, which is thought to work through stimulating the receptor of a special molecule called prostaglandin E2 (PGE2), which has diverse effects on the body including dilation of the blood vessels, uterine contractions, and bowel activity." So how does this affect your lashes? Says Burg, "The theory is that PGE2 also has a role in hair growth by stimulating hair follicles to enter the growth phase. There is some evidence for this in hair cells grown in laboratories, but no real evidence in clinical studies on people."
How to Use Castor Oil on Lashes
If you want to give castor oil a try to see if it will strengthen and grow your lashes, you have two options—an eyelash serum formulated with castor oil or just the oil by itself. Either way, Rahi suggests you perform a patch test by applying the product to an unseen area of your skin "to ensure you do not have any reactions or irritations from using the oil." Next, dip a cotton swab into the oil and apply to clean, dry lashes. You can do this as often as once daily and if you're using straight up castor oil, we suggest adding the ritual to your nightly routine (and rising off in the morning) so you're not walking around with thick oil on your eyes all day.
"Make sure you start by using a small amount to prevent dripping into the eye," says Rahi.
Finding success with lash-growth ingredients and products is null without having healthy lashes, to begin with. As it turns out, certain beauty habits are actually often preventing us from having the lengthy flutters we crave. "Large, heavy false eyelashes and stick-ons can cause traction damage to the eyelash follicles and eventually, can lead to follicle stress and death," says Burg. "Heavy eyeliner left on for very long periods may also impact eyelash follicle health, so it's important to ensure you cleanse as part of your nightly eye care routine." The same goes for mascara—sleeping in it might cause breakage and possible infection, so be diligent to remove every last stitch before your head hits the pillow.
Is Castor Oil Safe For Eyelashes?
"Castor oil is a safe natural [lash treatment], but it comes down to being careful when applying the oil and staying clear from getting the oil in the eye, which can cause irritation," says Rahi. "Look for pure, organic castor oil without any additives. To be extra cautious, always consult your dermatologist before using any new products especially those that are applied so close to your eye."
However, general practitioner Dr. Nicole Swiner says castor oil may be safe only for some pregnant women. "It's best of she is in her last trimester, as it can cause abdominal or uterine cramping or contractions," she explains. "Loose stool or diarrhea and nausea are also common side effects."
If you've recently had a lash lift, brow and lash expert Geneva Stockdale says to avoid water for 24 hours and product for 48. "After the instructed time I personally recommend applying oil to the lashes after a lash lift, castor is phenomenal as it helps with hair growth and integrity," she says. And if you want your lash tints to last as long as possible, castor oil might be best avoided, "There is a chance that the oils will breakdown the pigment in dye faster, however lash health is my priority," says Stockdale. As far as lash extensions, castor oil is a great way to nourish and hydrate the lashes after they're removed, according to Stockdale.
What about other ingredients you might want to try? "There have been some really promising research surrounding a protein called FGF5 and eyelash growth," says Burg. As a key regulator of hair growth inhibiting the protein could help grow longer hair and lashes. A 2021 study found that suppressing FGF5 and FGF18 (another hair-regulating protein) promoted hair growth in mice. Similarly in 2014, a study conducted on individuals with excessively long eyelashes found that they had deficiencies or mutations in FGF5.
The Final Takeaway
So, castor oil might not be the miracle answer to getting the long lashes of your dreams. But some proven benefits could improve the appearance. Since castor oil is safe to use on lashes, there's no harm in trying it out as long as you perform a patch test and take care not to get it in your eyes. As always, ask your dermatologist if you have any questions.
Frontiers in Pharmacology. "Suppression of FGF5 and FGF18 Expression by Cholesterol-Modifed siRNAs Promotes Hair Growth in Mice." 07 July, 2021.
Higgins CA, Petukhova L, Harel S, et al. FGF5 is a crucial regulator of hair length in humans. Proc Natl Acad Sci U S A. 2014;111(29):10648-10653. doi:10.1073/pnas.1402862111