Ceramide As

Ceramide AS is a skin-identical barrier lipid used at low concentrations (typically well under 1%) to support the stratum corneum and reduce transepidermal water loss. In clinical and real-world use, ceramides are generally non-stinging and well tolerated even in eczema-prone or compromised skin; irritation is uncommon and usually attributable to the overall formula (surfactants, solvents, preservatives) rather than the ceramide itself. Because rare reactivity is still possible in highly sensitized patients, I score it as exceptionally gentle rather than completely inert. Safety Notes: In commercial moisturizers/serums/cleansers, Ceramide AS is most often used as part of a ceramide blend at very low active levels; the lowest observed use is trace dosing (~0.0001%) for label support in multi-ceramide/cholesterol/FA systems, especially in rinse-off and budget leave-on products. Higher-end barrier-repair leave-on creams and concentrates sometimes push total ceramides into the ~0.1–0.5% range, with Ceramide AS itself reaching up to ~0.5% in high-strength consumer formulations (limited by cost, solubility/dispersion, and crystallization risk). Rinse-off products generally sit at the low end, while leave-on barrier creams/ointments occupy the high end.