What does the S in Ceramide AS mean?

It indicates a sphingosine base, as opposed to the phytosphingosine base marked by P in ceramides such as NP, AP and EOP.

Is a sphingosine-based ceramide better than a phytosphingosine one?

No such ranking is established. Barrier evidence supports ceramide blends that approximate the skin's own lipid composition rather than any single species.

Is sphingosine used on its own in skincare?

Yes. Sphingosine and phytosphingosine are the sphingoid backbones of ceramides and are also used as standalone cosmetic ingredients, typically at low percentages.

What CAS number does Ceramide AS have?

CAS numbers vary by ceramide species, so the specific number should be confirmed against the supplier's technical data sheet for the exact material used.

Is Ceramide AS restricted anywhere?

No. Ceramides are unrestricted cosmetic ingredients under EU CosIng and FDA cosmetic guidelines.

Ceramide AS — Ingredient Guide

How it works

Ceramides are named by a shorthand code describing the two halves of the molecule: the fatty acid and the sphingoid base. In Ceramide AS the A marks an alpha-hydroxy fatty acid and the S a sphingosine base — distinguishing it from ceramides such as NP, AP and EOP, which are built on phytosphingosine. Sphingosine itself is one of the sphingoid backbones to which fatty acids attach to form complete ceramides, and it is also used on its own as a cosmetic ingredient. Whatever the species, the function is shared: with cholesterol and free fatty acids in a ratio commonly cited as roughly 3:1:1, ceramides assemble into the lamellar bilayers between corneocytes that form the skin's main barrier against transepidermal water loss and against irritants entering. Topical ceramides are believed to integrate into that matrix and replenish lipids depleted by ageing, harsh cleansing, UV damage or atopic dermatitis.

The evidence

Clinical barrier-repair studies, including trials in atopic dermatitis and photoaged skin, support ceramide-containing moisturisers for reducing transepidermal water loss and improving barrier measures. As with every ceramide species, that support attaches to blends rather than to a single molecule — reproducing the skin's native lipid organisation is generally thought to require several ceramides together.

Suitability

Suitable for all skin types, most valuable for dry, sensitive, eczema-prone, ageing or barrier-compromised skin, including skin being treated with retinoids or acids.

Concentration

Ceramide blends are typically used at around 0.5%–2% total lipid content in barrier-repair products, frequently with cholesterol and fatty acids alongside. Note that each named ceramide is a distinct molecule with its own registry number, so a single CAS cannot be assumed to cover the whole class.

Conflicts & combinations

No practical conflicts are described. Ceramides are a supportive ingredient class, compatible with virtually all actives, and are best formulated with cholesterol, free fatty acids and humectants such as glycerin.