Ferulic Acid

Ferulic acid is a hydroxycinnamic acid common in plant cell walls. In skincare it is valued less as a solo brightener and more as a stabiliser and booster for ascorbic acidAscorbic acidStrongAscorbic Acid · Vitamin C (L-ascorbic acid)The active form of vitamin C; well-evidenced for photoageing at 10–20 % and low pH, but unstable.Open in the Index → (and vitamin E) antioxidant serums[1].

What it does

It scavenges reactive oxygen species and, at ~0.5% with 15% L-ascorbic acid and 1% α-tocopherol, stabilises the solution and approximately doubled photoprotection of skin in the landmark Lin et al. model — reducing erythema and UV-induced injury markers versus C+E alone[1]. A follow-on human study of a C/E/ferulic solution likewise showed significant protection against UV-induced damage[2].

The evidence

Photoprotection synergy is moderate-to-strong for the specific C+E+ferulic combination under controlled irradiation; broad anti-ageing or brightening claims for ferulic monotherapy are more limited/emerging. It is not a UV filter and does not replace zinc oxideZinc oxideStrongZinc Oxide · Inorganic UV filterBroad-spectrum mineral filter with the best tolerance profile; permitted to 25 % almost everywhere.Open in the Index →, titanium dioxideTitanium dioxideStrongTitanium Dioxide · Inorganic UV filterStrong UVB and short-UVA mineral filter; extensively reviewed for nano safety.Open in the Index → or organic sunscreen actives such as avobenzoneAvobenzoneStrongButyl Methoxydibenzoylmethane · Organic UVA filterThe main UVA1 organic filter in US sunscreens; photounstable unless paired with stabilisers.Open in the Index →.

How to use it

Look for it in low-pH vitamin C serums (often beside ascorbic acidAscorbic acidStrongAscorbic Acid · Vitamin C (L-ascorbic acid)The active form of vitamin C; well-evidenced for photoageing at 10–20 % and low pH, but unstable.Open in the Index → or sodium ascorbyl phosphateSodium ascorbyl phosphateModerateSodium Ascorbyl Phosphate · Vitamin C phosphate saltStable vitamin C derivative with surprisingly decent acne data; weaker than L-ascorbic for photoageing.Open in the Index →). Typical cosmetic use is well under 1%. Layer under sunscreen in the morning; it complements rather than substitutes SPF.