Castanea Sativa Seed Extract

Castanea Sativa (chestnut) seed extract is primarily used as an antioxidant/soothing plant extract, typically included at low concentrations (often <1–2%) in leave-on skincare. While not a strong “active” like acids or retinoids, botanical extracts can still trigger stinging or allergic contact dermatitis in a small subset of highly reactive or eczema-prone patients due to naturally occurring polyphenols/proteins and variable raw-material composition. Given its generally good tolerability but non-zero sensitization potential in compromised skin, it fits best as a gentle ingredient with minimal but real risk. Safety Notes: In mass-market leave-on products (creams/serums/toners), Castanea Sativa (Chestnut) Seed Extract is most often used as a minor botanical active or part of a multi-extract blend, commonly appearing at very low levels around 0.0005–0.05% as supplied/active (especially when the INCI represents a dilute glycerin/propylene glycol extract). Higher-strength consumer products marketed for antioxidant/firming/anti-glycation benefits and some mask/ampoule-style formulations can reach ~1–5% of the extract material, with practical upper limits driven by solubility, color/odor, and formula stability rather than specific regulatory caps (no specific EU/FDA concentration limit observed for this INCI).