If you've ever spent time looking up the best products for hair growth, you've probably read about castor oil. The popular product has long been referred to as a "miracle treatment" for hair, eyebrow, and eyelash growth — and right now, you can get one of Amazon's top-selling hair treatment oils, the Kate Blanc Cosmetics Organic Castor Oil, on sale for just $10 in an early Prime Day 2023 deal.

So, what exactly is castor oil? In short, it's a vegetable oil that's derived from castor beans. In a previous interview with InStyle, dermatologist Dr. Marina Peredo, MD, explained that it's "filled with omega-6, omega-9, and vitamin E, which all have nourishing and hydrating factors." And in another past interview, certified trichologist and colorist Bridgette Hill told InStyle that since castor oil is made up of fatty acids, it provides "essential proteins and nutrients to hair follicles," creating an optimal environment for new growth.

Kate Blanc Cosmetics Organic Castor Oil is a USDA-certified organic product (as evidenced by the official label on the bottle) with more than 56,000 five-star Amazon ratings. The 2-ounce bottle comes with a dropper in the top, an eyebrow spoolie, and a thin brush for easy application on your scalp, eyebrows, and eyelashes. You could also go for the 11-piece set, which is currently half-off and includes a 4-ounce bottle, plus five spoolies and five brushes — all of which you can get for just $14 while the deal is live.

Shop now: $10 (Originally $15); amazon.com

Shop now: $14 (Originally $25); amazon.com

In the reviews section, more than 5,000 shoppers shared their positive experiences with the oil. One person noticed that their "eyelashes are longer and wispy," their "eyebrows are getting thicker," and there are "tiny hairs growing" on their hairline after adding this product to their beauty routine. A second reviewer called it a "must-have for your hair growth needs."

Most shoppers like to apply the product before bed so it can soak into their skin overnight. "I use it at night, wrap my hair and in the morning my hair is soft and has a beautiful sheen," one wrote. And another user, who applied the oil to their eyebrows every night for a month, said their brows are now "so much fuller," adding that "the key is patience and consistency."

It's pretty clear that the Kate Blanc Cosmetics Organic Castor Oil has a massive following thanks to its effectiveness and low price, so if you ask us, it's worth giving it a shot. Just be sure to grab one of Amazon's most popular hair growth oil now while it's just $10.