Lipid

Lipid — a broad class of oil-soluble molecules including ceramides, fatty acids, cholesterol, and triglycerides that form the water-resistant matrix between skin cells. In skincare, lipids help seal moisture into the skin and reinforce the outer barrier that shields against irritants and water loss.

Key points

• The three dominant barrier lipids in the skin are ceramides, free fatty acids, and cholesterol.
• Skin lipids arrange into organized layers between cells, acting like mortar between the bricks of the outer skin.
• A deficiency in barrier lipids is associated with dryness, sensitivity, and conditions such as eczema.
• Cleansers and environmental stressors can strip surface lipids, which lipid-replenishing products aim to restore.

Frequently asked

Are lipids the same as oils?

Oils are one type of lipid, but the term lipid also covers structural barrier molecules like ceramides, fatty acids, and cholesterol that are not simple oils.

Why do lipids matter for dry skin?

Lipids form the matrix that holds skin cells together and limits water loss, so replenishing them can help dry, compromised skin retain moisture.

Related topics

• What Is a Humectant?
• What Is the Skin Barrier?
• The Lipid Bilayer of the Stratum Corneum

This is a foundational entry in the SYNC Skin Encyclopedia and is expanded over time. Educational information only — not medical advice.