Shoppers Call This Growth Serum 'a Must' for Stronger, Thicker Hair — and It's 36% Off Ahead of Prime Day

After the thrill of fun packaging wears off, there's not much excitement in waiting for your latest hair-care find to yield results. That being said, sometimes the formulas that take weeks, or even months, to work their magic end up being the most worth-it purchases — especially when it comes to regrowing your mane. Thinning scalps and shedding strands can be tricky to overcome, but committing to a routine can make all the difference, especially when it includes a product shoppers swear by.

Take the Hairfinity Botanical Hair Oil, for instance: With thousands of perfect ratings on Amazon, this serum restores fragile, damaged hair to its former strength and promotes new growth from the scalp. Jojoba, coconut, and olive oils moisturize, dry, flaking, dandruff-prone skin, creating a healthy environment for hair to grow and thrive, while vitamin E prevents breakage by fighting free radicals. Meanwhile, rosemary oil nourishes breakage-prone strands with antioxidants and even blocks DHT, a hormone that weakens and stops hair follicles from growing. Another key ingredient is collagen, an integral element of hair structure. While the protein hasn't been comprehensively studied for its strand-strengthening benefits, a number of people (including Jennifer Aniston and Kourtney Kardashian) swear by its benefits.

Buy It: Hairfinity Nourishing Botanical Oil, $26 (was $41), amazon.com

"After using this oil [for] a month my hair started to grow back in," wrote one reviewer, who gave the serum a try after noticing balding patches on their scalp. "This is a must-have if you are losing hair or desire to make your hair thicker, stronger, and healthy," they added. Another shopper who used the growth treatment three times a week for one year recorded 10 added inches to their length, dubbing the product "amazing" for its speedy results. "I promise you, it really worked for me," raved a third user who saw "so much new growth" after just three weeks of use. (BTW: One Shape editor swears by this Vegamour treatment for thicker hair.)

A final pro? This serum is currently 36 percent off ahead of Amazon Prime Day. While this "magic in a bottle" normally goes for $41, you can score it today for just $26 with this early deal.