Tetrahexyldecyl Ascorbate

Tetrahexyldecyl ascorbate (THDC, also known as ascorbyl tetraisopalmitate) is a lipid-soluble vitamin C ester that penetrates the stratum corneum far more efficiently than water-soluble forms. Once inside the cell, esterases release active ascorbic acid. THDC is exceptionally stable, non-irritating at neutral pH, and works at low concentrations of 1–3%. It stimulates collagen production, brightens hyperpigmentation, and — unlike pure vitamin C — pairs perfectly with retinol and exfoliating acids in the same routine. Its oil solubility makes it ideal for richer serums, facial oils, and night treatments aimed at anti-aging plus brightening without sensitisation.