Although, both of these ingredients do their best work under certain conditions: You want to apply a vitamin C serum on clean, dry skin so it can penetrate the skin cells, but you want to apply hyaluronic acid on a damp face so it can pull water into the skin. Vitamin C is also a vital part of the collagen synthesis process, helping collagen cross-link and support skin firmness. But it doesn’t just stimulate collagen production; it stabilizes the collagen2 you have, leading to overall wrinkle reduction. “Vitamin C is a key cofactor in the synthesis of collagen and elastin, [which helps] give your skin that plump and youthful appearance,” says Keira Barr, M.D., dual board-certified dermatologist.* You don’t need to be as precious with hyaluronic acid. Yes, applying on damp skin will make it easier for the humectant to pull in water, but it can also draw in that moisture from the surrounding environment, too. Let’s not forget: Hyaluronic acid can hold up to 1,000 times its weight in water, and you don’t necessarily have to provide that water yourself. “That way, you don’t need to worry that HA needs to go directly onto damp skin,” says board-certified dermatologist Ife J. Rodney, M.D., FAAD, founding director of Eternal Dermatology + Aesthetics. So you can apply your vitamin C first, let it dry completely, then apply your hyaluronic acid. Just remember to top everything off with a moisturizer—you still want to seal in the HA to lock in the hydration. Or, if you do want to apply your HA on damp skin to maximize its benefits, board-certified dermatologist Ava Shamban, M.D., founder of SkinFive and The Box by Dr. Ava, still recommends applying your vitamin C serum and letting it dry completely. “The highly reactive nature and low pH of vitamin C in serum form will usually allow it to penetrate the cleansed, dry skin quickly,” she says. After it dries, apply a water-based hydrating toner or essence (here are our favorites), then pat your hyaluronic acid serum onto the freshly misted skin. Again, follow up with a moisturizer to lock in the hydration. That said, you can always use vitamin C in the morning and HA in the evening. “In the evening, you’ll have even more benefits, since you won’t be layering it with vitamin C,” says Rodney. Of course, you can also take standalone hyaluronic acid and vitamin C supplements, but it’s pretty common to see them together in collagen formulas.
