Ceramides

The outer layer of skin is often described as bricks and mortar. The corneocytes are the bricks, and the mortar is a lipid mixture of ceramides, fatty acids and cholesterol.

So a ceramide cream is doing something unusual in this category: it is not acting on the skin, it is supplying the material the skin is built from. When that mortar is depleted, by eczema, by over-washing, by cold weather, water leaves and irritants get in. Replacing it is a straightforward premise.

Why the results are more modest than the premise

Two practical limits, and neither is a doubt about whether ceramides matter.

They penetrate poorly. The research literature is direct that topical ceramide use is limited by poor solubility and low skin permeability. A lipid designed to sit in a barrier is not a molecule that crosses one easily, which is why formulation work in this area is mostly about delivery.

Ratio matters more than presence. The barrier is a mixture, and the proportions between ceramides, cholesterol and fatty acids appear to matter more than the amount of any one of them. A product listing a ceramide has told you one component is there and nothing about the balance.

Reading a ceramide label

The names look like part numbers because they are. Ceramide NP, AP and EOP are the common ones, and the older numbering, ceramide 3, 6-II and 1, refers to the same molecules. A product listing several is offering more of the mixture than one listing a single type.

Phytosphingosine and sphingolipids are precursors and relatives rather than ceramides.

As everywhere in cosmetics, the amount is missing. Ceramides are expensive, they appear well down the ingredient list, and below 1 percent the order carries no information, which is the point made in the guide to reading a cosmetics label.

Where they sit against the alternatives

Worth saying plainly, because the price difference is large.

Petrolatum is the most effective occlusive there is and costs almost nothing. It does not supply ceramides; it stops water leaving while the skin rebuilds its own. For a barrier that is simply dry, it is hard to beat.

Niacinamide takes the third route: it prompts the skin to make more of its own ceramides rather than supplying them.

Supplying, sealing, or stimulating. All three are legitimate and they are frequently combined, and none of them is the one that had to be expensive.

Eczema and small children

Ceramide-containing emollients are widely used for eczema-prone skin, including in children, and that use is well established rather than a marketing position.

What a label cannot do is tell you whether a specific product suits a specific child. Eczema management is clinical, prescribed emollients exist for a reason, and the general approach to reading labels for a small child is on the page for parents.