Cholesterol

Cholesterol is one of the three key lipid classes of the stratum corneum — alongside ceramides and free fatty acids — and an often-overlooked hero of barrier repair. It stabilises the lamellar lipid matrix, contributes to membrane fluidity, and is required for proper assembly of the barrier sheets. Aged and atopic skin shows a skewed cholesterol-to-ceramide ratio, and topical correction with balanced lipid mixtures measurably improves barrier recovery. At 1–2% in creams it softens, smooths, and reduces irritation. It is not the "bad" cholesterol of blood tests — topical cholesterol is inert, skin-identical, and safe. Best used within complete barrier formulations rather than solo.