Isostearyl Palmitate

Isostearyl palmitate is a fatty acid ester emollient used to improve slip and reduce transepidermal water loss, typically present at a few percent up to higher levels in makeup and creams. It is not an active and is generally well-tolerated with low rates of irritation or sensitization in patch testing; the main risk is occasional intolerance or comedogenicity rather than true irritant dermatitis. For severely reactive or barrier-compromised patients, I still assign a very gentle score rather than inert because any occlusive emollient can rarely sting on fissured skin or contribute to follicular irritation in susceptible individuals. Safety Notes: Isostearyl palmitate is a common emollient/ester oil used at very low levels (~0.1–1%) as a slip and sensory modifier in lotions, sunscreens, and cleansers, where it may sit mid-to-late in the INCI list. In anhydrous leave-on products (lipsticks/lip balms, makeup primers, facial oils/serums, balm cleansers), it can function as a primary emollient and routinely reaches 20–40%, with some consumer-available high-slip anhydrous sticks/balms and color cosmetics pushing to ~50–60%. There is no specific EU/FDA maximum for this ingredient; practical upper limits are driven by product format, viscosity/structure, and compatibility with waxes and other oils rather than regulation.