Castanea Sativa Leaf Extract

Castanea sativa (chestnut) leaf extract is a botanical antioxidant/astringent ingredient typically used at low percentages, but it contains polyphenols/tannins that can sting or provoke dryness on compromised barriers. While not a common primary irritant in population patch testing, botanicals have meaningful variability and can trigger irritant reactions in eczema-prone or highly reactive patients, especially in leave-on products. Given the potential for barrier-tightening astringency and unpredictable plant-extract sensitivity, a mild score is the safest clinically-aligned assessment. Safety Notes: In commercial skincare, Castanea Sativa (Chestnut) Leaf Extract is most often used as a minor antioxidant/soothing botanical at very low levels (trace to ~0.1%) in leave-on toners, lotions, and cleansers, where it functions mainly as a label-claim extract within a broader botanical blend. Higher-strength consumer products (e.g., targeted anti-redness/antioxidant serums or ampouled concentrates) can reach ~1–3% when the extract is a primary featured active, with levels above this being uncommon due to solubility, color/odor, and stability/sensory constraints. There are no specific EU/FDA maximum limits for this botanical extract in cosmetics, so the observed range is driven primarily by typical supplier use-level guidance and real-world formulation practicality.