Study participants who massaged a peel composed of 8% vitamin C and 2% retinol onto clean, dry skin on their faces and necks for a 4 to 6-hour stretch once every three weeks saw sebum levels increase by as much as 65% after just 9 weeks. MORE: 6 Ways Your Hair Changes After 40 The dynamic duo works as a team, say the researchers: Retinol binds to protein receptors in your skin to rev lipid production in the skin, while vitamin C enhances collagen production and makes retinol, a typically unstable ingredient, last longer than it can alone. MORE: 9 Things That Could Make You Start Menopause Early Try the combo yourself by smoothing on InstaNatural Age Defying & Skin Clearing Serum ($22, instanatural.com), which contains 2.5% retinol and 20% vitamin C twice a day if you have oily skin, and once in the evening if you have sensitive skin, says Karen Hammerman, MD, a cosmetic dermatologist at Vanguard Dermatology in New York City. These potent ingredients can cause dryness or irritation, so daily use of a moisturizer and SPF 50 is a must (retinol makes your skin more susceptible to sun damage), and you may want to do once daily applications until your skin gets used to it, Hammerman adds.
