Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate

Pentaerythrityl Tetra-Di-T-Butyl Hydroxyhydrocinnamate is a high–molecular weight antioxidant/stabilizer used at very low levels (typically well under 1%) to prevent oil oxidation in formulas, with low skin penetration. Available safety and patch-test experience generally supports a low irritation profile, though rare contact reactions are possible with hindered phenolic antioxidants in highly reactive individuals. Given sensitive-skin risk management, it fits best as very gentle rather than inert. Safety Notes: This ingredient is a high-performance oil-phase antioxidant (often used to protect fragrance, oils, UV filters, and unsaturated emollients) and is typically dosed very low in mass-market leave-on and rinse-off products (commonly ~0.01–0.1%), with some formulas listing it around the 0.005% level when used as a secondary stabilizer alongside tocopherol/BHT. High-strength consumer-available products (especially anhydrous balms, facial oils, sunscreens, and long-wear color cosmetics where oxidative stability is critical) can use it up to about 0.5% as a primary antioxidant package component; higher levels are uncommon due to cost and diminishing returns rather than regulatory caps.