Ceramides

Ceramide As

INCI: CERAMIDE AS

Reviewed by Rosie · Last updated 14 Aug 2026

A lipid that reinforces the skin's natural moisture barrier and maintains hydration

Best For Skin Types

All, Dry, Sensitive, Mature

Addresses

Dryness, Sensitivity, Barrier repair, Hydration

Usage Frequency

Daily

What Is Ceramide As?

Ceramide AS is a type of ceramide, a naturally occurring lipid (fat molecule) found in the outermost layer of skin called the stratum corneum. It belongs to a complex group of sphingolipids that vary in structure depending on the length and saturation of their fatty acid chains. Ceramide AS specifically refers to a ceramide with an alpha-hydroxy fatty acid component.

In skincare formulations, ceramide AS functions as a skin conditioning agent, helping to reinforce the skin's lipid matrix. This lipid matrix is essential for maintaining the barrier that prevents water loss and protects against environmental stressors. Because it mimics the skin's own ceramides, it integrates into the intercellular spaces of the stratum corneum where it supports barrier structure and function.

How It Works

The stratum corneum, your skin's outermost protective layer, is structured like a brick-and-mortar wall. Ceramides are the mortar, filling the spaces between skin cells (corneocytes) alongside cholesterol and free fatty acids. Together, these lipids form organised lamellar sheets that create an effective barrier against water loss and external irritants.

When ceramide AS is applied topically, it deposits into these intercellular spaces, reinforcing their structural integrity. This strengthens the barrier function and reduces the amount of water that evaporates from the skin. A more robust lipid matrix also helps regulate skin pH and supports the skin's natural inflammatory responses, contributing to a calmer, more resilient complexion.

Clinical Evidence & References

Research confirms that ceramides, including those with alpha-hydroxy fatty acid chains, are fundamental to skin barrier structure and function. Studies show that ceramides comprise approximately one-third of the lipid content in the stratum corneum and are essential for maintaining skin hydration and preventing water loss. Evidence supports their use in managing dry skin and conditions characterised by barrier dysfunction, such as atopic dermatitis.

Whilst ceramide AS specifically has not been extensively studied in isolation, it belongs to a well-documented class of ceramides shown to support barrier repair and hydration. The research suggests ceramides are most effective when used alongside complementary lipids (cholesterol and free fatty acids) at balanced ratios, mimicking the skin's natural lipid composition. However, more targeted studies on ceramide AS at varying concentrations would help establish optimal usage parameters.

How to Use

Ceramide AS is typically found in moisturisers, serums, and barrier repair products. Apply to clean, slightly damp skin to allow better absorption and to help seal in hydration. It works well in combination with other barrier-supporting ingredients such as cholesterol and fatty acids. For dry or compromised skin, incorporate it into your routine twice daily; those with more resilient skin may use it once daily or as needed.

Safety & Precautions

Ceramides are generally well-tolerated and rarely cause irritation, making them suitable for sensitive and reactive skin types. No significant safety concerns have been documented, though patch testing is advisable if you have a known sensitivity to ceramides or related lipids.

Frequently Asked Questions

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Part of a family

Ceramide As is a variant of Ceramide AP, the form you will most often see on an ingredients list.

Helps strengthen skin's barrier Improves hydration and suppleness

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