We turned to the experts: Below, derms explain whether castor oil can help you look dolled-up and doe-eyed, and how to apply it for the best results. Though the actual clinical evidence is lacking, there is scientific weight behind the ingredient itself: Castor oil’s main compound is ricinoleic acid, a fatty acid that has antioxidant and anti-inflammatory properties. The oil also contains vitamin E, which can also help protect those hairs from environmental aggressors. And, finally, it’s both an emollient and an occlusive—meaning, it’s able to penetrate into the strands and keep moisture from seeping out. “It is super hydrating so lashes don’t become brittle and dry or break, which happens as we age,” Shamban notes. Ultimately, it’s the same conversation as castor oil for hair growth: Some swear by it; others simply don’t see the hype. That may be because “it depends on the length of the anagen (or growth) phase of your hair to begin with,” explains board-certified dermatologist Jeanine Downie, M.D. (That’s why some FDA-approved lash serums work by actually extending the growth phase of hair.) In other words, people with a naturally longer growth phase may see profound benefits from using castor oil—others, not so much. But for what it’s worth: Even if castor oil doesn’t promote lash growth, per se, its nourishing compounds can certainly keep the flutters you do have healthy and thriving. Of course, a lash serum might include a host of other healthy ingredients (such as aloe and peptides), which might give the concoction a moisturizing boost. But if you’d rather stick to straight castor oil, by all means. As for the few synthetic lash serums that are FDA-approved, those have been clinically shown to enhance lash length—unfortunately, castor oil (even when it’s infused into a serum) can’t measure up to those claims just yet. Of course, you’ll want to remove any and all makeup beforehand, so your lids don’t have any lingering product that could block the oil. Although, Shamban says you might not want to use an oil-based remover: “It may leave an oil coating on the lashes and preclude the castor oil from being applied directly on the lashes and lash line.” (Check out these other natural makeup remover options, some of which are oil-free.) Once you’re ready to apply, follow these simple steps: