Castor oil is a popular home remedy for longer, thicker eyelashes. But does it actually work? The short answer is that there is no strong scientific evidence proving castor oil grows eyelashes. However, some people report seeing improvements. This article explains what the research shows, how castor oil might work, and what you should know before trying it.
Does Castor Oil Help Your Eyelashes Grow?
The direct answer is that no well-designed clinical studies have confirmed that castor oil makes eyelashes grow. Most of the evidence is anecdotal — people share personal success stories online, but these are not controlled tests. The idea comes from castor oil’s main ingredient, ricinoleic acid, which may have anti-inflammatory and moisturizing properties. Some small studies on scalp hair and animal models suggest a possible effect, but human eyelash research is lacking.
What Does the Research Say?
Research on castor oil for hair growth is limited. A 2015 study in the Journal of Cosmetic Dermatology found that castor oil applied to mouse skin increased hair growth compared to a placebo. But animal results do not always translate to humans. A 2019 review in International Journal of Trichology concluded there is insufficient evidence to recommend castor oil for hair growth. No large human trials have studied eyelash growth specifically.
Some research suggests ricinoleic acid may inhibit a molecule called prostaglandin D2, which is linked to hair loss in some conditions. But this mechanism has not been tested in a way that proves eyelash growth. The FDA does not approve castor oil for lash growth, and it is not classified as a drug for this use.
How Is Castor Oil Supposed to Work?
Castor oil is a a thick vegetable oil extracted from castor beans. It is rich in ricinoleic acid, a fatty acid with known anti-inflammatory and antimicrobial properties. Proponents believe that when applied to the lash line, it:
- Moisturizes the lash follicles, reducing breakage
- Improves lash thickness and shine by coating the hair shaft
- May reduce inflammation that could inhibit growth
Moisturizing can make lashes appear healthier and less brittle, but that is different from stimulating new growth. Lash length and density are largely determined by genetics and the natural hair cycle. No topical oil can change your genetic programming.
How to Use Castor Oil on Eyelashes Safely
If you choose to try castor oil, use a pure, cold-pressed, hexane-free product. Avoid any with added fragrances or ingredients that could irritate the eyes. Apply a tiny amount using a clean mascara wand or a cotton swip to the base of your upper lashes — not directly into the eye. Do this at night and wash off in the morning. Start with a patch test on your arm to check for allergic reaction.
Safety note: Castor oil is not sterile. Applying it near the eye can introduce bacteria. If you wear contact lenses, remove them before application. Discontinue use if you experience redness, swelling, itching, or blurred vision.
What Are the Risks?
Castor oil is generally considered low-risk for external use on skin, but the eye area is sensitive. Potential side effects include:
- Allergic contact dermatitis — rash, itching, swelling
- Irritation if the oil gets into the eye — causing stinging, redness, or blurred vision
- Clogged meibomian glands along the lash line, which can lead to dry eye or styes
People with known allergies to castor beans should avoid it entirely. There are no established safety data for castor oil use during pregnancy or breastfeeding specifically on eyelashes.
What Are Better Alternatives for Lash Growth?
If you want scientifically supported options, consider products with prostaglandin analogs like bimatoprost (Latisse). Latisse is FDA-approved for eyelash growth and has strong clinical evidence. It works by prolonging the lash growth cycle. Side effects can include eye redness, darkening of the iris, and skin darkening at the application site.
Other alternatives include:
- Lash serums with peptides and biotin — less evidence than Latisse but some small studies support ingredients like myristoyl pentapeptide-17.
- Eyelash extensions — immediate visual effect, but require maintenance and can damage natural lashes if not applied properly.
- Healthy diet — adequate protein, iron, and vitamins (especially biotin and vitamin E) support hair health, but will not specifically grow lashes beyond what is normal for you.
Be cautious of products that make dramatic claims without clinical data. Many lash growth products are not regulated by the FDA.
Frequently Asked Questions
Can castor oil make your eyelashes grow longer?
No clinical evidence proves castor oil lengthens eyelashes. Some users report changes, but this may be due to better conditioning rather than actual growth.
How long does it take for castor oil to work on eyelashes?
Without proven efficacy, no timeline can be given. If any effect occurs, it would typically take weeks to months, similar to the normal lash growth cycle.
Is castor oil safe for eyelashes?
Castor oil is generally safe for external use, but it can cause eye irritation or allergic reactions. Always patch-test and avoid getting oil in your eyes.
What is better than castor oil for eyelash growth?
FDA-approved treatments like bimatoprost (Latisse) have strong evidence for lash growth, unlike castor oil.
