Hydroxystearyl Phytosphingosine — INCI reference

What it is

Hydroxystearyl Phytosphingosine is a ceramide-class ingredient consisting of a phytosphingosine sphingoid base coupled to a hydroxystearyl (C18 alpha-hydroxylated) acyl chain. This structure closely mimics the naturally occurring Ceramide AP subclass found in the stratum corneum, which comprises roughly 9–14% of skin ceramides and is required for permeability barrier homeostasis. In formulations, it integrates into the intercellular lipid lamellar matrix, reinforcing the organized bilayer structure that governs transepidermal water loss and resistance to external irritants. Phytosphingosine-based ceramides are also associated with upregulating barrier proteins (filaggrin, loricrin), stimulating endogenous ceramide biosynthesis, and modulating inflammatory signalling. The ingredient is used in moisturisers, barrier repair creams, and sensitive-skin treatments.

Safety & warnings

Ceramide-class ingredients including phytosphingosine derivatives are generally considered safe for topical use and non-sensitising. Pure phytosphingosine raw material carries GHS hazard statements for mild skin, eye, and respiratory irritation under handling conditions, but at typical cosmetic use concentrations these concerns are not clinically relevant. No significant comedogenicity, photosensitisation, or endocrine-disruption concerns have been identified for this class. Suitable for sensitive and compromised skin formulations.

Origin & sourcing

Produced synthetically by N-acylation of phytosphingosine — a sphingoid base originally isolated from plants and fungi, now commercially obtained via yeast fermentation — with hydroxystearic acid (an alpha-hydroxylated C18 fatty acid). The resulting molecule is biomimetic, structurally equivalent to ceramides naturally present in human skin lipid lamellae.

History

Phytosphingosine was first characterised in 1884. Interest in its N-acylated derivatives as functional ceramide replacements in cosmetics grew through the 1990s and 2000s, driven by research on barrier lipid composition. Alpha-hydroxy ceramides of the AP class were identified as a distinct and essential subclass of stratum corneum ceramides, leading to development of topical analogues including Hydroxystearyl Phytosphingosine for barrier-repair cosmetic applications.

Questions everyone asks

What is Hydroxystearyl Phytosphingosine and how does it differ from regular phytosphingosine?

Hydroxystearyl Phytosphingosine is an N-acylated derivative of phytosphingosine, where a hydroxystearic acid chain is attached to the sphingoid base. This converts the free sphingoid base into a complete ceramide analogue that integrates directly into the skin's lipid lamellae, whereas unmodified ph

How does Hydroxystearyl Phytosphingosine support the skin barrier?

It mimics the naturally occurring Ceramide AP subclass in the stratum corneum, slotting into the intercellular lamellar lipid structures that regulate transepidermal water loss. It also stimulates endogenous ceramide biosynthesis and upregulates key barrier proteins such as filaggrin.

Is Hydroxystearyl Phytosphingosine suitable for sensitive skin?

Yes. Ceramide-class ingredients including phytosphingosine derivatives are well-tolerated and are routinely used in formulations designed for sensitive, dry, or compromised skin conditions such as atopic dermatitis.

Is this ingredient natural or synthetic?

It is synthetic but biomimetic. The phytosphingosine base is derived from yeast fermentation or plant sources, while the hydroxystearyl acyl chain is produced by chemical N-acylation. The resulting molecule is structurally equivalent to ceramides naturally found in human skin.