Isostearyl Isostearate

Isostearyl isostearate is a fatty acid ester used as an emollient/skin-conditioning agent and slip enhancer, typically included at a few percent up to ~10%+ in creams, balms, and makeup. As a large, non-volatile lipid with minimal water solubility, it has low penetration and is generally non-sensitizing with a low rate of irritant reactions in patch-testing experience. Rare intolerance can occur in highly reactive or acne-prone patients (more from occlusion than true irritation), but overall it is very gentle for sensitive skin. Safety Notes: Isostearyl isostearate is a lipophilic emollient/ester used at low levels (~0.1–1%) as a slip agent and solubilizing/emollient component in lotions, sunscreens, and cleansers (rinse-off typically staying on the lower end). In leave-on products it commonly appears around 1–10% to build cushion, reduce tack, and improve spread in creams and facial oils. The upper end (20–40%) is observed in anhydrous or high-oil systems such as cleansing oils/balms, makeup primers, and some lip products where it can function as a primary emollient/texture vehicle; it is not specifically concentration-restricted by EU/FDA beyond general cosmetic safety requirements.

Suitability