Triisostearin

Triisostearin is a lipid-based emollient/thickener used in makeup and creams (often a few percent up to higher levels in color cosmetics) that is generally well tolerated and not a common irritant in standard patch-testing experience. While it is not a biologically active ingredient and has low inherent reactivity, its heavy, occlusive nature can occasionally contribute to discomfort or comedone-like flares in some reactive or eczema-prone users, so I score it as very gentle rather than inert. Safety Notes: Triisostearin is used as an emollient/structuring lipid and pigment-wetting agent, and in many leave-on creams/lotions it appears at low, functional levels (~0.05–1%) to improve slip, cushion, and stability. In color cosmetics and anhydrous balm/stick formats (lipsticks, lip balms, cream foundations, cleansing balms), it is often a primary oil-phase component and can reach ~10–25%, with some consumer-available high-occlusion sticks/balms and pigment-rich products observed up to ~30–35%. It is uncommon in rinse-off products except at low levels (typically <2–5%) due to cost and limited benefit versus other lipids.