Ceramides and skin function.

Ceramides are lipid molecules that form the glue holding your skin's barrier together—they make up roughly one-third of your skin's outer layer (along with cholesterol and fatty acids in equal amounts). When ceramides are depleted or imbalanced, your skin barrier weakens and loses water, which is why many skin conditions show lower ceramide levels. Adding ceramides back through skincare can help restore barrier function, but the research notes that incomplete or mismatched lipid formulations won't cut it.