To buy: $14 (was $24); amazon.com. The serum uses two types of hyaluronic acid to firm, brighten, and visibly soften wrinkles. Other ingredients include vitamin C, glycerin, and castor oil—all of which hydrate your skin and improve elasticity. The lightweight formula quickly absorbs into the skin and doesn’t clog pores, so it’s safe to use on dry, oily, or combination skin types. L’Oréal recommends applying two to three drops to clean skin twice daily for the best results. Reviewers found it to be especially hydrating when it was massaged into damp skin. “At first, I didn’t notice a difference [after using this product] except [for] redness on my cheeks in the morning. Today as I was putting on my makeup I noticed the mirror looked airbrushed,” another customer wrote. “So I decided to do a one-week contrast, and my jaw hit the floor. I can’t believe this drugstore serum outperformed a $200 high-end product. I wish I had started using this 20 years ago!”