Ceramides are lipids, not actives. They don’t do anything to the skin in the conventional sense – they are the skin. Ceramides make up roughly 50% of the intercellular lipid matrix of the stratum corneum, the outermost layer. Along with cholesterol (25%) and free fatty acids (15%), they form a lamellar bilayer structure that functions as the skin’s primary physical barrier against water loss and environmental entry.
When ceramide levels are depleted – through ageing, over-exfoliation, harsh surfactants, or conditions like eczema – the lamellar structure becomes disordered. Gaps appear. Water escapes (transepidermal water loss rises), irritants penetrate more easily, and inflammatory responses become more frequent. This isn’t sensitive skin – it’s compromised barrier.
Topical ceramides work by replenishing the depleted lipid pool. The skin can incorporate exogenous ceramides into the intercellular matrix, though the process is less efficient than endogenous production. A complete formulation targets all three key components – ceramides, cholesterol, and free fatty acids – in a ratio that approximates the skin’s natural proportions. Single-ceramide products are less effective than multi-ceramide systems.
Three ceramides appear most frequently in effective formulations: ceramide NP (ceramide 3), ceramide AP (ceramide 6-II), and ceramide EOP (ceramide 1). Studies using a three-ceramide combination showed significantly better barrier repair than individual ceramides used separately.
Niacinamide increases endogenous ceramide synthesis, making it a useful pairing. Retinol does the same over time. Neither replaces a dedicated ceramide formulation for actively compromised barrier – but both support long-term barrier resilience.