Sunscreens with an SPF of 15 can block more than 90% of ultraviolet (UV) radiation. Even with this level of protection, some UV light still penetrates the skin and can trigger the formation of free radicals.

Free radicals are unstable molecules that can damage DNA, accelerate skin aging, impair immune function, and increase the risk of skin cancer. This process—known as oxidative stress—contributes to wrinkles, age spots, and other signs of premature aging. Antioxidants help neutralize free radicals, limiting their ability to cause cellular damage.

Research from the University of Illinois at Urbana–Champaign’s Laboratory for Fluorescence Dynamics demonstrated that ultraviolet exposure generates free radicals in the stratum corneum, the outermost layer of the skin and its first line of defense against environmental stressors. This finding is important because it shows that oxidative damage can occur even within the skin’s protective barrier.

Traditional sunscreens work primarily by blocking or absorbing ultraviolet radiation. They do not directly neutralize free radicals once they are formed. Because some UV exposure still occurs—even with proper sunscreen use—oxidative stress can continue despite UV filtering.

What More Recent Research Shows

Over the past decade, dermatology research has increasingly focused on antioxidant-enhanced photoprotection:

  • Studies published in the Journal of Investigative Dermatology, Dermatologic Therapy, and Photodermatology, Photoimmunology & Photomedicine show that topical antioxidants such as vitamins C and E, ferulic acid, niacinamide, polyphenols, and carotenoids can reduce UV-induced oxidative stress, lipid peroxidation, and inflammatory signaling in the skin.

  • Combination antioxidant formulas appear more effective than single antioxidants. Vitamin C helps regenerate oxidized vitamin E, improving overall antioxidant capacity in the skin.

  • Antioxidants have been shown to reduce markers of photoaging, support collagen integrity, and improve skin barrier function when used consistently alongside sunscreen.

  • Some evidence suggests antioxidant supplementation—both topical and dietary—may enhance the skin’s resistance to UV-induced immune suppression, a factor linked to skin cancer risk.

These findings support the concept that antioxidants address biologic damage that occurs downstream of UV exposure, rather than replacing UV filtration itself.

Important Note

Antioxidants are supportive—not a replacement for sunscreen.
They should be viewed as an adjunct to sun-safe behavior, which includes appropriate sunscreen use, protective clothing, and avoidance of excessive sun exposure. Antioxidants help mitigate oxidative damage that sunscreen alone does not fully prevent.

In this way, antioxidant support may help close an important gap in skin protection—addressing free radical injury while sunscreens focus on blocking ultraviolet radiation.