The One Skincare Product You Shouldn't Mix With Vitamin C

Vitamin C is not only the ultimate immune booster; it also has several anti-aging benefits for the skin (via CNN). Vitamin C is an antioxidant, which means that it can shield skin cells from free radicals resulting from UV exposure. Dr. Noelani González, who is the director of cosmetic dermatology at Mount Sinai West, told Today, "Free radicals are unstable molecules that can cause damage to our cells."

Vitamin C also helps with skin discoloration and hyperpigmentation by suppressing the skin's melanin production. In turn, darker spots lighten and your skin looks more luminous. Dermatologist Dr. Patricia Wexler told CNN, "Vitamin C promotes collagen production, which has the potential to thicken the dermis, diminish fine lines, and is essential for firm, youthful skin." Wexler added, "Vitamin C helps to repair damage from sun exposure and collagen loss by encouraging healthy cell turnover and regeneration."

It's a skincare active that is recommended for everyone to use. Dermatologist Dr. Anne Chapas told CNN, "It's great for all skin types and ages." It works well with several ingredients, but there's one active that should absolutely not be combined with vitamin C, and that is retinol (via InStyle). According to Huffington Post, retinol can leave your skin especially sensitive to sunlight. Since vitamin C is an antioxidant that protects your skin from sun-related damage, it's recommended to use vitamin C during the day and retinol at night.

Dermatologist Dr. Y. Claire Chang told Huffington Post, "Vitamin C and retinol work optimally in different pH environments and thus should typical not be combined." She added, "Vitamin C products are formulated to be at a low pH of less than 3.5, while retinol works best at a pH of 5.5-6."

Wexler recommended vitamin B and hyaluronic acid to be used alongside vitamin C, but also advised against mixing vitamin C with niacinamide, citing incompatible pH levels (via CNN). According to CNN, vitamin C's benefits are boosted when combined with other antioxidants. Chapas said, "This works best with vitamin E and ferulic acid." She added, "Together, they have optimal absorption benefits when it comes to anti-aging, skin brightening, and protection against free radical damage."

Chang told Huffington Post that you should also avoid combining benzoyl peroxide and vitamin C because benzoyl peroxide can oxidize, or break down vitamin C. Chang added, "Vitamin C and hydroxy acid products could potentially be used together, as they both work in acidic environments." But she cautioned against it, saying, "because both are made in acidic formulations, the combination can be more irritating for the skin." 

So what is vitamin C's best friend and hype man? Sunscreen. The two work together to fight sun damage like Batman and Robin. Dermatologist Dr. Shari Marchbein told InStyle, "Vitamin C serums should always be layered under sunscreen because they complement one another and will protect skin against UV damage."