10-Hydroxystearic Acid

10-Hydroxystearic acid (10-HSA) is a mono-hydroxylated fatty acid derived from oleic acid, a naturally occurring component of plant and animal oils. It is produced through a biochemical process using enzymes and belongs to the class of skin-conditioning agents.In skincare formulations, 10-HSA functions as both a skin conditioner and protectant. It works at a cellular level to influence how skin cells communicate and support the structural proteins that keep skin firm and resilient.

10-HSA activates a cellular receptor called peroxisomal proliferator-activated receptor alpha (PPARα). This activation prompts skin fibroblasts — the cells responsible for producing collagen — to increase their output of structural proteins. By supporting collagen synthesis, it helps maintain the skin's framework and firmness.Additionally, 10-HSA appears to modulate the skin's response to sun damage by reducing markers of UV-induced cellular stress, though this effect is still being characterised in human studies.

10-HSA is typically incorporated into serums, moisturisers and targeted treatments. It can be used daily as part of a regular skincare routine. It is compatible with many other active ingredients, including retinoids, which may offer complementary benefits when used together. Apply to clean skin as directed by individual product instructions.

10-HSA is generally well-tolerated with no widely reported adverse effects at typical cosmetic concentrations. As with any skincare ingredient, patch test if you have sensitive or reactive skin.