Ferulic Acid
Also known as 4-Hydroxy-3-methoxycinnamic acid, 3-(4-Hydroxy-3-methoxyphenyl)acrylic acid, Ferulic acid
“No regulator has issued a verdict on this ingredient.”
Ferulic acid (CAS 1135-24-6; C10H10O4) is a phenolic hydroxycinnamic acid antioxidant derived from plant cell walls. Topical application for up to 24 hours did not cause skin irritation in a comparative skin delivery study — transepidermal water loss, erythema, and skin pH were unaffected by ferulic acid and its derivatives (Zhang et al., Int J Pharmaceutics, PMID 20692328). A retrospective review of 33 patients who received a combination serum (15% vitamin C, 1% vitamin E, 0.5% ferulic acid) immediately after ablative CO2 laser resurfacing reported no adverse events attributable to the topical ferulic acid-containing formulation (Johnson et al., J Cosmetic Laser Therapy, PMID 35290149). Ferulic acid has not been assessed by the Cosmetic Ingredient Review (CIR) Expert Panel as of the September 2022 All Conclusions QRT — it is absent from both the 2017/2018 and 2022 QRT editions. CosIng coverage could not be directly verified due to JS-rendered SPA limitations.
Potent phenolic antioxidant: scavenges reactive oxygen species generated by UV radiation and environmental oxidative stress; the conjugated double bond and phenol ring enable efficient radical trapping
Synergistic stabilization of co-antioxidants: ferulic acid at 0.5% stabilizes L-ascorbic acid and alpha-tocopherol in combination serums, enhancing their photoprotective efficacy — the basis of the well-studied vitamin C + vitamin E + ferulic acid serum formulation pattern
Photoprotection enhancement: when combined with chemical UV filters, ferulic acid increased SPF measurements by 37% and UVA protection factor by 26% with a satisfactory safety profile in sun-exposed conditions (Peres et al., J Photochem Photobiol B, PMID 29864725)
No skin irritation observed in controlled topical delivery study at tested concentrations up to 24 hours of exposure (Zhang et al., PMID 20692328)
- · Limited solubility in water (approximately 0.78 g/L) and low solubility in oils (up to 0.2%) constrains formulation options and effective delivery
No CIR safety assessment exists as of September 2022 — ferulic acid is absent from both the 2017/2018 QRT and the September 2022 All Conclusions QRT; regulatory coverage gap limits formal safety verdict
Formulation instability: ferulic acid is pH- and temperature-sensitive; undergoes decarboxylation in unstable formulations producing 4-hydroxy-3-methoxystyrene as a degradation byproduct (Wang et al., J Cosmetic Sci, PMID 22152493); stability requires careful pH and solvent control