Castor Isostearate Succinate

Castor Isostearate Succinate is a castor-oil–derived ester used mainly as an emollient/surfactant in rinse-off and leave-on products, typically at low-to-moderate concentrations. As a high–molecular weight, non-volatile lipid derivative, it is generally well-tolerated and not a common cause of irritant dermatitis in patch testing, though very reactive or barrier-impaired eczema patients can occasionally sting or flare with any surfactant-like ester. Given the low inherent reactivity but nonzero risk in compromised skin, a very gentle score is most appropriate. Safety Notes: In commercial skincare and cosmetics, Castor Isostearate Succinate is typically used as an emollient/texture modifier and pigment-wetting/binder component, appearing at low levels (~0.1–1%) in creams/lotions and color cosmetic-type hybrid skincare where it fine-tunes slip and payoff. Higher levels (5–15%) are observed in anhydrous balms, stick products, cleansing balms, and some oil-based makeup removers where it contributes significant structuring, glide, and solubilization/wetting of oils and waxes. Use levels are generally higher in leave-on anhydrous systems than in rinse-off emulsions, and are constrained mainly by desired viscosity/sensory rather than specific regulatory maximums.