Does castor oil work for your eyelashes and skin?

Castor oil for eyelid inflammation (blepharitis) has the strongest clinical backing of all its applications. In a small randomised trial with 26 participants, applying the oil to the eyelid margins twice a day for four weeks produced clear improvements: fewer eyelash crusts, less thickening of the eyelid margin, and less eyelash loss. No side effects were reported. It is a small study, so the finding needs confirmation, but it was designed as a controlled trial.

For dark circles under the eyes there is preliminary evidence. A study in 22 patients found that applying a cream twice a day for two months reduced darkness, pigmentation, and wrinkles. However, there was no placebo group, so it is impossible to know how much of the effect would have occurred without the oil. The researchers themselves state that larger, controlled studies are needed.

Castor oil is also mentioned as a possible option for dry eyes caused by meibomian gland dysfunction. This is based on a review article, however, not on the researchers' own trial participants. The idea is plausible because the oil may slow moisture loss, but solid clinical evidence is still lacking.

Two other mentions are less relevant for everyday users. In nail fungus treatment, castor oil is only an excipient in a formula that contains actual antifungal agents; the contribution of the oil itself cannot be isolated. Stories on social media about castor oil combined with nutritional yeast for hair and nails are personal accounts from internet users, not clinical research. No conclusions can be drawn from them.

The popular use of castor oil for eyelash growth (thicker, longer) is not supported by any of the controlled studies. The only eyelash-related outcome in the available research concerns reduced shedding in blepharitis, not growth in healthy eyelashes. Do not expect miracles on that front.