As someone with fine to medium hair that seems to shed a lot, I always include a biotin shampoo in my haircare routine. I've found that biotin-based shampoos help my hair look thicker and fuller after drying and speed up hair growth — plus, there are noticeably less strands in my shower drain after use. If that sounds like something you're in the market for, Amazon currently has quite a few of its most popular biotin shampoos on sale, including customer-favorite brands like Redken, R+Co, and Avalon Organics.

Shop the Best Hair Growth Shampoos on Sale at Amazon:

While biotin can be taken orally to encourage hair growth, you can also apply the vitamin topically via hair products for similar results. Dr. Debra Jaliman, a board-certified dermatologist in New York City, previously told InStyle that "biotin helps nourish the hair follicles and stimulate the growth of existing hair," adding that it also helps with the production of keratin, a protein that "strengthens hair."

Amazon's shampoo sale starts at just $7 with the Avalon Organics Therapy Thickening Shampoo, a plant-based shampoo formulated with biotin, saw palmetto, quinoa protein, and vitamin E, which all work together to strengthen and thicken hair. Thousands of shoppers said the Avalon Organics shampoo provides results quickly, with one customer even saying it "doubled" the appearance of their hair after one shower.

Shop now: $7 (Originally $11); amazon.com

Quite a few shampoo and conditioner sets are discounted too, like Redken's Extreme Length Shampoo and Conditioner for just $22 and this under-the-radar duo from Bellisso, which is currently a top best-seller in Amazon's hair regrowth shampoo and conditioner categories. The Bellisso shampoo and conditioner have over 10,000 five-star ratings from customers who said it helped their strands look fuller, shinier, and aided in less shedding. Alongside biotin, the Bellisso formula also includes hydrolyzed keratin and spirulina extract, which reduce breakage and promote hair growth, respectively.

Shop now: $22 (Originally $48); amazon.com

Shop now: $30 (Originally $35); amazon.com

Ready for some long and strong hair? Shop more biotin shampoos on sale at Amazon, here.