As for its inclusion in Youth to the People Triple Peptide + Cactus Oasis Serum, hyaluronic acid comes in four different forms. Made to penetrate every layer of skin with moisture, the 4D hyaluronic acid is combined with another anti-aging favorite, peptides. Together, the ingredients should firm, moisturize, and plump up skin. As Susan Weinkle, an assistant clinical professor of dermatology at the University of South Florida, tells Real Simple, “When you hydrate the skin from outside, you make fine lines less noticeable.” That’s definitely been the experience of those who used Youth to the People’s serum, including a shopper who shared, “I’ve been using it for about three days now and definitely notice a difference. [My] skin looks like it has a healthy glow. My forehead lines aren’t as noticeable.” Another reviewer said the fine lines on their face appeared “blurred,” adding, “My skin definitely feels more plump and hydrated.” To buy: $54; youthtothepeople.com. Users of the serum should expect similar results, as Weinkle also told Real Simple that “hyaluronic acid works by drawing in moisture to give your skin a smooth, and almost plumped-out appearance, making fine lines and wrinkles less prominent.” Hyaluronic acid is generally tolerated by multiple skin types, but first-time users may want to conduct a patch test. Free of fragrance, Youth to the People’s serum can be applied twice daily to the under-eye area, as well as the face and neck. Experts previously noted to Real Simple that hyaluronic acid is best applied to wet skin post-cleansing. “It gives a mega-dose of hydration to the skin, and you feel it instantly,” another fan wrote of the serum. “From the first use, my skin was incredibly hydrated, plump, and soft to the touch.” Others reported similar results, including a shopper, who shared, “I have been using this product for a couple [of] days now and I can feel and see noticeable differences. My skin feels extremely soft and hydrated. It has even made my skin glow.” Experience the many benefits of hyaluronic acid and purchase this serum for yourself from Youth to the People now.