Antioxidants in sunscreen: what the evidence shows, and what it doesn’t
Vitamin E, vitamin C and ferulic acid are often added to sunscreens. Human evidence that they add visible benefit is limited. Here is what is known and how CSL formulation scientists use them.
By CSL Formulation team · Evidence checked by CSL scientists
At a glance
- What it is
- Ingredients such as vitamin E (tocopherol), vitamin C and ferulic acid added to sun care to mop up free radicals
- Main benefits
- May reduce some UV-induced skin damage markers; help protect the formula itself from oxidation
- Levels tested in trials
- 15% vitamin C, 1% vitamin E and 0.5% ferulic acid in a serum (not a sunscreen); levels in sunscreens rarely tested
- Time to results
- 4 days of pre-treatment in the key human study; no long-term sunscreen trials
- Watch for
- Overstated claims, stability of vitamin C, and no SPF contribution
01What is it?
Antioxidants are ingredients that neutralise free radicals, the unstable molecules UV and visible light create in skin. Sunscreens often include vitamin E, vitamin C derivatives, ferulic acid or plant extracts. They do not filter UV and add nothing to SPF.
02What it does
UV filters stop most, but not all, UV reaching the skin. The idea is that antioxidants deal with the free radicals that still form. Human studies show a vitamin C, E and ferulic acid serum can reduce UV redness and DNA damage markers, but there is little evidence that adding antioxidants to a sunscreen gives a visible difference.
03The evidence
Studies below were checked against the publisher, DOI or journal record on 26 Sep 2026. We list design and size so you can judge the strength of each result.
| Study | Design | Who and how long | What it found |
|---|---|---|---|
| Murray et al. 2008, Journal of the American Academy of Dermatology (Elsevier) Source | Vehicle-controlled human study | Volunteers, 4 days of 15% vitamin C, 1% vitamin E and 0.5% ferulic acid serum, then solar-simulated UV | Less redness, fewer sunburn cells and fewer thymine dimers than vehicle. This was a serum, not a sunscreen. |
| Fonseca et al. 2025, Journal of Cosmetic Dermatology (Wiley) Source | Open-label clinical study plus lab tests, no control group | 34 women aged about 46, 28 days (collagen at 84 days); sunscreen (static SPF 32.9) with encapsulated antioxidants | Hydration up to +30%, with most users reporting firmer skin; in skin samples, UV free radicals fell 37%. Weak evidence: no comparison sunscreen. |
| Pasuch Gluzezak et al. 2024, Frontiers in Physiology (Frontiers) Source | Laboratory study (cells and reconstructed skin), no human data | Avobenzone–resveratrol hybrid filter | Cut UVA-induced free radicals by 30.7% in reconstructed skin. Shows the concept only. |
| Peñín et al. 2026, Advanced Healthcare Materials (Wiley) Source | Laboratory chemistry study, no human data | Eight new filter molecules in test sunscreens | Two molecules scavenged 73% and 53% of free radicals in a test tube, versus about 1% for avobenzone and octinoxate. |
| Hughes et al. 2013, Annals of Internal Medicine (ACP) Source | Randomised controlled trial (oral, not topical) | 903 adults, 4.5 years; 30 mg beta-carotene daily by mouth | Oral antioxidant supplement had no overall effect on skin ageing, unlike daily sunscreen. |
Antioxidants are a sensible supporting addition to sunscreen, but the human evidence for a visible extra benefit is limited. Keep claims modest and tied to testing, for example “with antioxidants” or “helps defend skin against free radicals” if the finished product has been tested for it. Never suggest they replace or boost SPF.
04How CSL formulation scientists use it
- Use vitamin E (tocopherol or tocopheryl acetate) at low levels to protect oils and filters from oxidation; this is its most reliable job in sunscreen.
- Choose stable vitamin C derivatives in sunscreens; pure L-ascorbic acid needs a low pH that does not suit most filter systems.
- Check antioxidants do not destabilise UV filters or change colour, and confirm SPF and UVA results after adding them.
- Support any “free radical” claim with a test on the finished product, not on the ingredient alone.
05Regulatory and claims
Common antioxidants such as tocopherol, ascorbic acid derivatives and ferulic acid are widely used cosmetic ingredients and are not UV filters. In the US, sunscreens are OTC drugs, so antioxidant claims must not imply extra sun protection beyond the tested SPF and broad-spectrum result. CSL regulatory specialists confirm each ingredient’s status in each target market and keep claims cosmetic.
06Questions brands ask
Do antioxidants make a sunscreen stronger?
No. They do not raise SPF. They may deal with some free radicals that form despite filters, but visible extra benefit has not been shown in controlled trials.
Is it worth adding vitamin C and E to a sunscreen?
As a supporting feature, yes, if they stay stable and do not upset the filters. Keep claims modest.
Can an antioxidant serum be used under sunscreen?
Yes. A vitamin C, E and ferulic acid serum reduced UV damage markers in a human study, and layering it under sunscreen is a common routine.
07References
- Murray JC, Burch JA, Streilein RD, Iannacchione MA, Hall RP, Pinnell SR. A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid provides protection for human skin against damage caused by ultraviolet irradiation. J Am Acad Dermatol. 2008;59(3):418–425. Link
- Fonseca AP, Ribon R, Cascais L, et al. Benefits of a multifunctional sunscreen formulation containing nanoencapsulated antioxidants in the skin protection against UV radiation and blue light: clinical and preclinical studies. J Cosmet Dermatol. 2025;24(6):e70282. Link
- Pasuch Gluzezak AJ, Dos Santos JL, Maria-Engler SS, Gaspar LR. Evaluation of the photoprotective and antioxidant potential of an avobenzone derivative. Front Physiol. 2024;15:1347414. Link
- Peñín B, Losantos R, Funes-Ardoiz I, Sampedro D. Integrated visible light and oxidant protection through multifunctional sunscreens. Adv Healthc Mater. 2026;15(28):e71125. Link
- Hughes MCB, Williams GM, Baker P, Green AC. Sunscreen and prevention of skin aging: a randomized trial. Ann Intern Med. 2013;158(11):781–790. Link
Used in: Sun protection
Update log
- Evidence reviewed and page published by CSL scientists
This page summarises published research for brands and formulators. It is general information, not medical advice, and results in studies depend on the full formula tested.
