What are skin lipids? Ceramides, cholesterol, and fatty acids explained

Key Takeaways

• Skin lipids are the fats that fill the spaces in the skin’s outermost layer, and they help support the moisture barrier.

• A 2022 review in Molecules puts the mix at roughly 40% to 50% Ceramides, 25% cholesterol, and 10% to 15% free fatty acids by weight. Counted by molecule, the three are present in roughly equal amounts.

• Harsh soaps can strip these lipids, which may leave skin feeling tight and looking visibly drier.

What skin lipids are and where they sit

The outermost layer of skin is called the stratum corneum. Researchers often picture it as a brick wall. Tough, flattened, protein-rich units are the bricks, and a lipid-rich matrix fills the gaps between them as the mortar. A 2022 review of soaps and syndets in Molecules uses exactly that “bricks and mortar” picture.

That mortar is made by the skin itself. When people talk about skin lipids and the moisture barrier, they usually mean three fats in it: Ceramides, cholesterol, and free fatty acids.

How the three lipids divide up the mix

The Molecules review reports that the lipid matrix “predominantly contains ceramides (40–50%), cholesterol (25%) and free fatty acids (10–15%).” Those figures are by weight. A 2024 review in the Journal of Lipid Research gives a similar split “by weight” and describes the same mix as “a 1:1:1 M ratio,” meaning roughly equal numbers of molecules of each. Ceramides are the largest share by weight, not by count.

Cleveland Clinic dermatologist Amy Kassouf describes Ceramides as “the grout that keeps the building blocks of the skin together.” Cholesterol and free fatty acids sit alongside them in the same layers.

What strips lipids from skin

Harsh cleansing can strip these lipids. The Molecules review explains that harsh soaps can disrupt the lipid layers by “extracting endogenous cholesterol, fatty acids and ceramides.” It links repeated use of harsh soaps to visible dryness, roughness, and a tight feeling after washing.

Water temperature plays a part too. Another Cleveland Clinic dermatologist, Melissa Piliang, says hot water “washes away all those healthy natural oils.”

The routine side of all this, from choosing a cleanser to how long recovery can take, is covered in a guide to caring for a stressed moisture barrier. And if you’re not sure whether your skin is short on oil or on water, the difference between dry and dehydrated skin is a useful next read.

Frequently Asked Questions

Are the Ceramides in skin care the same as the ones in skin?

Not exactly. Cleveland Clinic explains that natural Ceramides are found in the skin of humans and other animals, while synthetic Ceramides are made in a lab and are the type commonly used in skin care products.

What are Ceramides usually paired with in a moisturizer?

Cleveland Clinic names three partners: emollients, which form a film on skin; humectants, which draw water in; and occlusives, which help hold moisture in.

When is the best time to apply a moisturizer with Ceramides?

Dr. Kassouf’s advice is to apply moisturizer within three minutes of showering or washing your face, while skin is still damp.