4 Things to Stop Doing Once You Turn 35

What you used to do: Subject your skin to a barrage of harsh, drying acne products (hello, salicylic acid scrubs!). It made sense then, because in your 20s, your skin was pretty oily and hard to dry out, says Jessica Wu, MD, a board-certified dermatologist and a clinical assistant professor of dermatology at University of Southern California's Keck School of Medicine.

Why that's a bad idea now: The acne you're dealing with in your 30s is likely different than the whiteheads that popped up in your 20s. "It's starting from deeper within the skin, and more due to inflammation than oil," says Wu. Plus, skin tends to become drier and more sensitive with age, so using those products will leave you flaky and irritated.

What to do instead: Swap your acne arsenal for gentler but still effective products with ingredients like sulfur, Wu's top choice for handling 30-something acne. Keep in mind that you may need to change to more moisturizing versions of your other products as well, say Ranella Hirsch, MD, a board-certified dermatologist in Boston. For example, "I often give women in their 20s a vitamin C gel, but a gel formula can be too drying by the mid-30s," says Hirsch. "A vitamin C serum will be more hydrating. You're getting the same effects from the active ingredients—you're just changing the vehicle they take to get into your skin."