Silybum Marianum Fruit Extract

Silybum Marianum (milk thistle) fruit extract is primarily an antioxidant/soothing botanical used at low concentrations (commonly well under 1%) and is generally well tolerated in leave-on products. However, as a complex plant extract it can still trigger irritation or allergic contact dermatitis in a small subset of highly reactive or eczema-prone patients, especially when formulations contain multiple botanicals. Given that nonzero sensitization potential exists but routine irritancy is uncommon, a gentle score is appropriate. Safety Notes: In commercial skincare, Silybum Marianum (milk thistle) fruit extract is most often used as a minor botanical antioxidant/soothing support ingredient at very low levels (around 0.0005–0.1%) in leave-on creams/serums and rinse-off cleansers, reflecting typical supplier-use levels and INCI list placement. Higher-strength consumer-available products (botanical-focused serums, ampoules, masks) can reach ~1–5% extract, especially when the extract is the headline active or part of a standardized botanical complex; above this is uncommon due to solubility, sensory, and stability constraints rather than regulation. No specific FDA/EU cosmetic concentration limit is set for this extract, so the practical upper end is driven by formulation feasibility and market practice.