Much like rosemary oil, castor oil has long been associated with hair growth. But is the natural remedy really as legit as some people claim? Sure, it’s known to have beneficial properties (more on those ahead), but does it really have the ability to regrow thinning hair or halt hair loss in its tracks? To find out once and for all, we tapped several board-certified dermatologists for their honest input on castor oil, how it works and its effectiveness when it comes to hair growth. They also shared a few product recommendations — including the best hair oils — to consider should you choose to incorporate the highly lauded ingredient into your hair care routine.
What is castor oil?
Let’s start with the basics. According to Dr. Joshua Zeichner, a board-certified dermatologist based in New York City, castor oil is an oil derived through cold-pressing the seeds or beans of the castor plant, which is found in Africa, India and South America. “Castor oil is loaded with ricinoleic acid, a potent antioxidant that protects the skin from free radical damage that causes collagen damage and wrinkles,” explains Zeichner. “It contains fatty acids [that] naturally have emollient benefits to hydrate and soothe the skin.”
Dr. Marisa Garshick, another board-certified dermatologist based in New York City, adds that in addition to antioxidants and fatty acids, castor oil is also rich in protein and other beneficial nutrients. “As a result, it can be helpful for the skin, scalp and hair,” she says. “Castor oil provides hydration and conditions the hair since it’s rich in ricinoleic acid and fatty acids, which serve as natural emollients for the hair.”
It’s also worth noting that castor oil is unlike most other oils that are mainly composed of fats, according to Dr. Michele J. Farber, a board-certified dermatologist from Philadelphia.
Does castor oil grow hair?
There is no concrete clinical evidence to support castor oil’s ability to grow hair. So while we know it’s a nourishing oil with beneficial results as a hair and scalp treatment, more research is needed in order to determine if it can promote growth.
“Castor oil contains ricinoleic acid, a type of fatty acid, which may boost circulation in the scalp and subsequently promote healthier and stronger hair, but there is no conclusive evidence that castor oil can promote hair regrowth,” confirms Garshick. “However, anecdotally, people have noticed improvement, and since it has antimicrobial and antifungal properties and helps to strengthen the hair and nourish the scalp, it promotes a healthy environment for hair regrowth.”
Farber is on the same page. “While there is no concrete scientific evidence to support this, based on the nourishing composition of castor oil, it is reasonable that castor oil provides an environment for hair growth,” says Farber. “It is also a humectant, so hydrating the hair follicles may help prevent breakage.”
How to use castor oil for hair growth
You may opt for pure castor oil or to use a product that contains the ingredient. Either way, a commonly asked question is how long you should leave castor oil in the hair for hair growth. According to Farber, it’s best to start by using a small amount for a short period of time — around 15 to 20 minutes — in order to prevent clogging pores around the hair follicles. Garshick, however, says you can leave castor oil on for several hours or even overnight, depending on the specific formulation and what your hair and scalp can tolerate. She adds, “When using it for hair growth, it is best to use it for at least three to six months for optimal results.”
What are the disadvantages of castor oil for hair?
Castor oil is generally well tolerated across the board; however, some may have a sensitivity to it, which can result in irritation. “There have been some allergic reactions to castor oil noted, which may lead to a chance in getting allergic dermatitis,” says Garshick. “Overuse and improper hair washing of the castor oil may also lead to buildup, which may also contribute to irritation and breakouts.”
With this in mind, it’s always best practice to patch test on a small area of skin before using castor oil all over your scalp — that, and to ensure you wash your hair and scalp really well after using it.
Best castor oil for hair
If you’re looking for an affordable option that’s received countless rave reviews, this under-$10 pick from Mielle is the way to go. “The combination of rosemary, mint, castor oils and other essential oils help to boost circulation, which aids in stimulating hair follicles to help with hair growth and thickening,” explains Garshick. Of course, results will vary, but there’s something to be said for the fact that it’s garnered so much positive feedback.
Recommended by Farber, this pure cold-pressed castor oil has nearly 65,000 reviews on Amazon for a 4.5-star rating. It’s a solid pick if you’re interested in trying castor oil completely on its own. For best results, the brand recommends letting it set for at least one hour before rinsing it out.
“This cold-pressed castor oil contains humectants, vitamin E and omega fatty acids, which work together to keep the hair healthy and hydrated,” says Garshick of Briogeo’s bestselling oil. “It can be used on the hair, as well as eyebrows and eyelashes.”
Recommended by Garshick, this clinically proven hair treatment contains a hero blend of antioxidants, along with biotin and hydrating panthenol. “The formula incorporates caffeine and castor oil and works as an overnight leave-in treatment to help boost hair density,” says Garshick. With consistent use, you should notice less shedding and hair fall.
“This oil is a favorite, made with castor oil and ashwagandha, which is thought to be an antioxidant as well as an adaptogen that lowers stress hormones,” says Farber of Fable & Mane’s bestselling pre-shampoo oil. In addition, it also contains “Dashmool,” which the brand says is a cocktail of 10 roots that act as a calming remedy for the scalp.
On top of peptides, this water-light hair serum contains a powerhouse blend of antioxidants, vitamins, humectants and conditioners to help nourish the hair and support overall scalp and hair health. Garshick calls out its inclusion of castor oil and caffeine to boost circulation and support healthy hair.
Other beauty products we love
Celebrities and our editors alike swear by this product to strengthen their hair. Try using it at least 20 minutes before you shampoo your hair. Put it on damp hair, watch a TV show, make breakfast, relax, do whatever you need to do. Then shampoo and condition your hair, and oh my gosh, we promise you’ll see a difference.
This under-$50 tool is a personal favorite and Underscored's choice of best affordable hair dryer. It quickly dries and styles hair with simple settings and a big oval-shaped brush to amp up the hair's volume. Just be cautious — the One-Step gets quite hot, so you'll definitely want to use a heat protector spray.