---
title: "Ceramides — Glossary | School of Dermatology"
url: https://schoolofdermatology.com/glossary/ceramides
description: "Learn what ceramides are, their critical role in the skin barrier, and why ceramide-containing moisturizers are essential for healthy, hydrated skin."
lang: en
---

Glossary

# Ceramides

SAIR-uh-mydz

## 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: https://schoolofdermatology.com/glossary/barrier-function
Lipid Barrier: https://schoolofdermatology.com/glossary/lipid-barrier
Stratum Corneum: https://schoolofdermatology.com/glossary/stratum-corneum
Emollient: https://schoolofdermatology.com/glossary/emollient

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