Ceramide NP, AP, EOP: decoding the ceramide names on a label

Turn over a moisturizer and you might see ceramide NP, ceramide AP and ceramide EOP lined up in the ingredient list, like a secret code. It is a code, but a simple one. Once you know what the letters stand for, you can read those names in a few seconds, and you’ll also know what the research can and can’t tell you about them.

First, what a ceramide is made of

Ceramides are fats (lipids) that sit between the flattened dead cells of your skin’s outermost layer, the stratum corneum. Together with cholesterol and free fatty acids, they form the “mortar” that keeps water in and irritants out. Ceramides make up nearly half of that mortar by weight.

Every ceramide is built from two pieces joined together:

• a sphingoid base, a long chain that acts as the backbone
• a fatty acid, a second long chain attached to it

Change either piece, or the length of its chain, and you get a different ceramide. Scientists have identified 23 classes of ceramide in human skin, made up of well over a thousand slightly different molecules. The class names simply say which kind of fatty acid is paired with which kind of base.

How to read the letters

The name has two parts. The first letter or letters describe the fatty acid. The last letter describes the base.

The fatty acid (first letters)

• N stands for non-hydroxy: a plain fatty acid chain.
• A stands for alpha-hydroxy: the fatty acid carries an extra hydroxyl group (an oxygen-hydrogen pair) near its start, which changes how the molecule links to its neighbours.
• EO stands for esterified omega-hydroxy: a very long fatty acid with a second fatty acid, linoleic acid, hooked onto its far end.

The base (last letter)

• S is sphingosine.
• P is phytosphingosine, a version common in plants and yeast as well as in skin.
• G on a label refers to sphinganine, which researchers usually write as dS (dihydrosphingosine).
• H is 6-hydroxysphingosine, a base found in skin but less common on labels.

So ceramide NP is a plain fatty acid on a phytosphingosine base. Ceramide AP is an alpha-hydroxy fatty acid on phytosphingosine. Ceramide EOP is the long, esterified type on phytosphingosine, and ceramide EOS is the same type on sphingosine.

Where did “ceramide 1, 2, 3” go?

If you’ve been reading labels for a while, you may remember numbered names. Those were the older ingredient names under INCI, the international system that standardizes names on cosmetic labels. The numbers were retired and replaced with the letter system, which describes the actual chemistry.

An expert safety review by the Cosmetic Ingredient Review panel set out the switch:

• Ceramide 1 became ceramide EOP
• Ceramide 2 was split into ceramide NS (sphingosine-based) and ceramide NG (sphinganine-based)
• Ceramide 3 became ceramide NP
• Ceramides 4 and 5 both became ceramide AS
• Ceramide 6 II became ceramide AP

Old and new names refer to the same ingredients, and for a while products could carry either one, so older packaging may still show the numbers.

You may also spot ceramide-like names that don’t start with “ceramide” at all, such as hydroxypalmitoyl sphinganine or caproyl sphingosine. They’re close chemical relatives of ceramides, and the same safety review assessed them alongside the ceramides. Some other products use pseudo-ceramides, synthetic molecules designed to behave like ceramides without matching their exact structure.

Which of these are actually in your skin?

All the classes you’ll commonly see on labels (NP, AP, NS, AS, EOP and EOS) have natural counterparts in the human stratum corneum. The safety review noted that the cosmetic versions are defined with the same three-dimensional shape as the ceramides found in skin.

The EO ceramides deserve a special mention. Researchers call them acylceramides. Their chain is extraordinarily long, about 70 carbon atoms counting the linoleic acid on the end, and they make up roughly a tenth of the ceramides in skin. In lab models of skin lipids, they’re needed to form a particular layered arrangement, called the long periodicity phase, that’s characteristic of a healthy barrier. When they run low, as seen in atopic dermatitis (the most common form of eczema), psoriasis and some inherited scaling conditions, that arrangement is weakened and the barrier leaks more.

A 2025 review of eczema skin found lower total ceramides, fewer NP, NH, EOS, EOH and EOP ceramides, and a shift toward shorter chains. That’s one reason ceramide names show up so often on products aimed at dry, eczema-prone skin.

What the evidence says about each type

This is where the label runs ahead of the science.

A 2021 review searched for controlled trials of ceramide-containing formulations and kept 12 good-quality studies, mostly in eczema and very dry skin. Ceramide products did as well as or better than the comparison products in every one. But the authors pointed out that it often wasn’t clearly described which ceramides were used, and the formulas, durations and comparison products all differed. They called for research on the efficacy of the different types, because no trial has isolated the effect of one ceramide type on real people’s skin.

Lab work adds a few clues but no verdict. In one model of skin lipids, ceramide EOP was a weaker barrier builder than ceramide EOS and needed a much higher concentration to form the long periodicity phase. That’s a membrane experiment in a lab, not a study of anyone’s skin, so it doesn’t tell you which product to buy.

Two more things are worth knowing:

• Amounts are usually small. In a 2013–2014 industry survey reported by the safety review, the highest concentration of the main ceramides in leave-on skin care was 0.2%.
• Ceramides work as a team. They need cholesterol and free fatty acids in roughly balanced amounts to form proper layers, so a formula’s overall design matters more than one star ingredient.

Are they safe?

The 2015 safety review concluded that the ceramides it examined are safe as used in cosmetics. Human patch tests showed no skin irritation with ceramide NP or ceramide AP, and animal tests of ceramide NP and several others found no allergic sensitization. The manufacturing information the panel received showed these ingredients are made synthetically, some are plant-based, and ingredients from cattle brain or spinal cord aren’t permitted in cosmetics.

If a ceramide product stings or makes you itchy, the culprit is more often something else in the formula, such as fragrance. If irritation doesn’t settle after you stop the product, check in with your pharmacist or doctor. A fragrance-free moisturizer is a sensible place to start if your skin reacts easily.

The letters on a ceramide name are just a recipe: fatty acid first, base last. NP, AP, NS, AS, EOP and EOS all mirror classes your skin makes itself, and the old numbers mean the same ingredients. What the label can’t tell you is whether one type beats another, because that hasn’t been tested yet. Look for a well-built, fragrance-free moisturizer you’ll actually use every day, and let the alphabet be a bonus, not the reason you buy.