Does castor oil really help with hair growth? The answer may surprise you

Anyone who's experienced hair thinning or shedding strands has likely considered adding castor oil to their beauty regimen. After all, it's relatively inexpensive and easy to get your hands on. If you believe people on the internet, it's also a no-fail way to get thicker, stronger strands. "My hair has gotten stronger and [has grown] inches," one shopper said of a popular castor oil sold on Amazon. Another shopper added, "I put this product on my scalp before I go to sleep, and I wake up with thicker, more full hair!"

It's tempting to believe the hype about castor oil, but it's worth digging a little deeper first. Is this humble product as powerful as people suggest? Can it really regrow hair when applied topically — and if so, how quickly? Below, dermatologists weigh in on just how effective castor oil is when it comes to hair growth.

There is no scientific evidence that castor oil promotes hair growth or hair thickness.

Every dermatologist we surveyed said the same thing: There is no scientific proof that castor oil grows hair. "Most of the evidence regarding the effectiveness of castor oil on hair growth has been anecdotal," says Dr. Michele Green, a cosmetic dermatologist in New York City. "There is no definitive evidence that castor oil stimulates hair growth in areas such as the scalp or eyebrows."

"Castor oil won't increase the number of hair follicles or the diameter of existing hair strands," adds Dr. T.N. Rekha Singh, a dermatologist based in India.

Castor oil does have hair care benefits.

While there is no direct link between castor oil and hair growth, dermatologists say it has other benefits. "Castor oil contains ingredients such as ricinoleic acid and fatty acids that have a moisturizing and nourishing effect on the hair," says Dr. Lori Ramirez, a Utah-based dermatologist.

According to Green, castor oil also has inflammatory properties that can help improve circulation and stimulate hair follicles. That means more nutrients and oxygen can reach your hair follicles, so your hair is less prone to breakage.

Too much castor oil can be a bad thing.

Whatever you do, don't douse your hair in castor oil. "Castor oil is a very thick and sticky substance," Ramirez says. She cautions that using too much can have the opposite effect of your desired results. "There has been matting or felting of the hair when over-using castor oil. This is a condition in which the hair becomes irreversibly tangled and needs to be cut," Ramirez explains.

Not all castor oil is the same.

As castor oil has grown in popularity, it's become more accessible. You can buy a bottle for less than $10, but it's important to note that not all castor oil is created equal. "When shopping for castor oil, it's crucial to look for 100% pure, organic and cold-pressed castor oil," says Dr. Anna Chacon, a dermatologist in Miami. "This ensures that you're getting a high-quality product without any additives or chemicals."

Another thing to look for? Castor oil that's free of hexane, a chemical solvent used to extract the oil from castor seeds. "The hexane extraction process can remove some beneficial properties," Singh explains.

Looking for effective ways to grow your hair? Check out our top hair growth products for women.

The reviews quoted above reflect the most recent versions at the time of publication.