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Glossary 

# Ceramides

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## Definition

Ceramides are a family of waxy lipid molecules that occur naturally in the skin and make up about 50% of the lipids in the stratum corneum. They play a crucial role in maintaining the skin's barrier function by forming a protective layer that limits water loss and shields the skin from environmental damage and irritants. As we age, or when the skin is stressed, ceramide levels decline, leading to dryness, irritation, and increased sensitivity. Skincare products containing ceramides — particularly ceramide NP, AP, and EOP — help replenish the lipid barrier. They work best when combined with cholesterol and fatty acids in a ratio that mimics the skin's natural composition. Ceramide-rich moisturizers are recommended for dry skin, eczema, rosacea, and post-procedure recovery.

## Related Terms

[Barrier Function](/glossary/barrier-function)[Lipid Barrier](/glossary/lipid-barrier)[Stratum Corneum](/glossary/stratum-corneum)[Emollient](/glossary/emollient)

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