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Ceramides

Also known as: ceramide, ceramide NP, physiological lipids, 3:1:1 ratio

Ceramides are a diverse family of sphingolipids that, with cholesterol and free fatty acids, organise the stratum-corneum permeability barrier. In skincare, 'ceramide' names an ingredient, not a guaranteed finished-product effect: performance depends on species, companion lipids, concentration, vehicle and tested population.

Evidence status

Moderate

The structural role of ceramides in human stratum corneum is well established. Finished-product evidence is formulation- and population-specific, commonly short term, and frequently produced by parties with a commercial interest in the result. No universal ceramide percentage or lipid ratio has been clinically validated.

What ceramides are#

Ceramides are a structurally diverse family of sphingolipids — not one interchangeable molecule. They differ by chain length, by headgroup, and by which of the several ceramide classes they belong to.[1, 2]

That matters more than it sounds. “Contains ceramides” describes a category, in the same way “contains protein” does. It does not tell you which ones, or whether they resemble what is missing from a particular client’s skin.

The native lipid matrix#

In the stratum corneum, ceramides sit alongside cholesterol and free fatty acids in an organised extracellular lipid matrix — the mortar between the corneocyte bricks.[1, 3]

That matrix is often described as roughly 50% ceramides, 25% cholesterol and 10–15% free fatty acids by mass.[1]

Note that carefully, because it is the source of a common slip. Composition by mass is a different quantity from the molar ratios used in formulation. The two get quoted interchangeably and they are not the same number.

Chain length matters too, and in a clinically relevant direction: in non-lesional forearm skin from adults with atopic eczema, shorter ceramide profiles correlated with altered lipid organisation and reduced barrier function.[3]

Where the 3:1:1 ratio comes from#

If you have been taught anything about ceramides in a product context, it is probably that they need to be present in a ceramide-dominant 3:1:1 molar ratio with cholesterol and free fatty acids.

That figure comes from a single optimisation experiment, and that experiment was an acute barrier-disruption model in hairless mice.[4]

And the paper is messier than the slogan. It started from equimolar mixtures of ceramides, cholesterol and fatty acids, which allowed normal recovery, and found that repair accelerated as the ratio of anyof those lipids was increased up to three-fold. Ceramide did not uniquely occupy the “3” position — cholesterol-dominant and fatty-acid-dominant mixtures worked too. Its only human note is that “similar preliminary results were obtained in damaged human skin”.

So the three-component, ceramide-dominant 3:1:1 rule is later product shorthand rather than a verbatim research result. This page said the experiment “identified” that ratio until August 2026, which gave the folklore a cleaner origin than it has — the same error we criticise elsewhere, made while debunking.

We went looking for a human clinical validation establishing the ratio as a requirement for a finished product to work. We did not find one.[no source found]

The interest behind it

One more thing belongs next to that finding. Three of the four authors of that paper — Elias, Feingold and Thornfeldt — are named inventors on the EpiCeram patent, the ceramide-dominant 3:1:1 prescription product marketed on that ratio.

That does not make the science wrong. Plenty of good science is done by people who then commercialise it. But a ratio that became an industry standard, traced to one mouse experiment, authored by the people who patented the product embodying it, is a chain worth seeing in full — particularly when it is repeated to practitioners as settled physiology.

What the clinical evidence shows#

Here is the part the category does not advertise.

In a three-week trial of 39 childrenwith mild-to-moderate atopic dermatitis — randomised 1:1:1, so thirteen per arm — no statistically significant efficacy difference was detected at any time point between an over-the-counter petrolatum ointment, the 3:1:1 ceramide-dominant prescription cream and a glycyrrhetinic-acid cream. The petrolatum was at least 47 times more cost-effective.[5, 6]

Say that precisely, because we did not.This page said petrolatum “matched” the ceramide product. Failing to detect a difference between thirteen children and thirteen children is not proof that two products perform the same — the trial was not designed as an equivalence or non-inferiority study, and its own authors say the sample was not sufficient to establish superiority either. Cochrane’s reanalysis of the itch outcome makes the imprecision visible: MD 4.51 mm, 95% CI −16.54 to 25.56, p=0.67. That interval is wide enough to contain a meaningful advantage in either direction. It happens to favour petrolatum numerically.

The defensible reading is not “petrolatum is as good”. It is that a small trial found no detectable difference, at a fraction of the cost — which is still an uncomfortable result for a category sold on its lipid ratio.

There is positive formulation evidence too. In 58 adults with dry, eczema-prone skin, a specific ceramide-containing cream improved selected 28-day measures against a comparator.[8]That trial was funded by the company that owns the brand tested — which does not invalidate it, and does mean it is not independent.

The structural problem with all of it: a ceramide-containing cream is also an occlusive, a humectant and a vehicle. A result from the finished formula cannot be assigned to the ceramides in it.[5, 6, 7, 8]i

None of this means ceramide products do not work. It means the evidence supports particular formulations rather than the ingredient, and that a well-made simple emollient is a legitimate comparator rather than an inferior one.

What a label can and cannot tell you#

In Great Britain and Northern Ireland alike, ingredients present at 1% or more are listed in descending order of weight — and ingredients below 1% may be listed in any order after them. That exception is doing most of the work here, because ceramides are exactly the kind of ingredient likely to sit under the line.[10, 11]

So an ingredient list can confirm that a declared ceramide is present. It usually cannot tell you its percentage, its rank among the other sub-1% ingredients, or a lipid ratio. This page previously said the list showed “roughly where they sit in the formula”, which is only true above 1%.

So a product cannot be assessed as “3:1:1” from its INCI list, and we found no validated consumer-facing ceramide percentage or threshold that predicts whether a finished product will work.[no source found]

If a brand claims a specific ratio, that is a claim they must be able to substantiate on request — not something you or your client can verify from the packaging.

The niacinamide connection#

Niacinamide is routinely described as increasing ceramide synthesis, which is why the two are so often formulated together.

The headline number comes from cultured human keratinocytes — a 4.1 to 5.5-fold rise in ceramide synthesis after six days, in work authored at a cosmetics manufacturer.[9]

The same paper also has a human arm, and this page erased it until August 2026. Topical application in dry skin increased stratum-corneum ceramides and free fatty acids and reduced TEWL. What the accessible abstract does not give is how many people, on what body site, in what formulation, or by how much — so it is an incompletely reported human signal rather than nothing at all.

Both halves matter. The mechanism is real and the human direction is there. What is not established is that applying niacinamide to a client’s face raises their stratum-corneum ceramide content by a clinically meaningful amount.

In professional practice#

  • Recommend formulations, not ingredients. The evidence attaches to specific products, and always has.
  • Don’t dismiss a simple emollient. In the one head-to-head trial, petrolatum matched the ceramide-dominant product at a fraction of the cost. For a client on a budget that is a real and defensible option.
  • Treat the 3:1:1 ratio as an origin story, not a standard. It came from a mouse model and has never been validated in humans as a requirement.
  • A TEWL improvement is not proof. It does not identify a ceramide deficiency, nor show that ceramides caused the change.[3, 7, 8]i
  • Ask who funded the study when a brand cites one. Most of this literature is commercially connected.

What remains uncertain#

  • Whether topical ceramides incorporate into the human stratum-corneum lipid lamellae, or simply sit on top as occlusion.
  • Whether any lipid ratio outperforms another in human skin.
  • Whether ceramide-containing products beat well-formulated non-ceramide emollients when the comparator is chosen fairly.
  • Whether matching ceramide species to a specific deficiency would work better than a generic mixture.

Common misconceptions#

“Products need a 3:1:1 ceramide ratio.”

That ratio comes from an acute barrier-disruption model in mice, and no human trial has validated it as a requirement.[4]

“Ceramide creams beat basic moisturisers.”

In the head-to-head trial, no significant difference was detected between an over-the-counter petrolatum moisturiser and the prescription ceramide product — in thirteen children per arm, which is too few to call that a match — and the petrolatum cost dramatically less.[5, 6]

“I can tell the ceramide content from the label.”

An INCI list gives descending order, not percentages or ratios.[10, 11]

“All ceramides are the same.”

They are a diverse family, and chain length correlates with barrier function in eczema-prone skin.[3]

“Niacinamide boosts your ceramides.”

In cultured keratinocytes. That is a rationale, not a demonstrated effect on a client’s stratum corneum.[9]

Frequently asked questions#

Are ceramide moisturisers worth the money?

Specific formulations have real evidence. But the honest answer is that a well-made simple emollient matched a ceramide-dominant prescription product in the one head-to-head trial, so cost is a legitimate factor rather than a compromise.[5, 6]

Does the ratio on the box mean anything?

You cannot verify it from the label, and the ratio itself has never been validated in humans.[no source found]

How much ceramide does a product need?

No validated threshold exists that predicts clinical efficacy across finished products.[no source found]

If a client’s TEWL improves, did the ceramides work?

Not established. TEWL does not identify a ceramide deficiency, and the vehicle, occlusion and humectants in the same product could account for the change.[3, 7, 8]i

Why is so much of this research industry-linked?

Because cosmetic ingredients rarely attract independent funding — and in this case the authors of the foundational ratio paper are named inventors on the patent for the product built to it. We flag the interest on each source rather than picking which ones to disclose.[4]

References#

Each source is graded by evidence tier. Tier 4 material (manufacturer documents, expert consensus, practitioner experience) is useful for protocol and context, and is never presented as equivalent to independent clinical evidence.

  1. van Smeden J, Janssens M, Gooris GS, Bouwstra JA. The important role of stratum corneum lipids for the cutaneous barrier function. Biochimica et Biophysica Acta. 2014;1841(3):295–313.Tier 4Supports: Ceramide diversity, the organised extracellular lipid matrix, and the approximate mass composition of the native matrix.
  2. Masukawa Y, Narita H, Shimizu E, et al. Characterization of overall ceramide species in human stratum corneum. Journal of Lipid Research. 2008;49(7):1466–1476.Tier 3Supports: Analytical characterisation showing ceramides are a structurally diverse family rather than one interchangeable molecule.
  3. Janssens M, van Smeden J, Gooris GS, et al. Increase in short-chain ceramides correlates with an altered lipid organization and decreased barrier function in atopic eczema patients. Journal of Lipid Research. 2012;53(12):2755–2766.Tier 3Supports: In non-lesional ventral-forearm stratum corneum from adults with atopic eczema, shorter ceramide chain profiles correlated with altered lipid organisation and reduced barrier function.Funding / interest: Supported by COST and STW; instrumentation involvement from River Diagnostics.
  4. Man MQ, Feingold KR, Thornfeldt CR, Elias PM. Optimization of physiological lipid mixtures for barrier repair. Journal of Investigative Dermatology. 1996;106(5):1096–1101.Animal studyTier 3Supports: MOUSE MODEL (hairless mice) of acute barrier disruption. READ THE ABSTRACT CAREFULLY, because the folklore has a cleaner origin story than the paper supports. It began from EQUIMOLAR mixtures of ceramides, cholesterol and fatty acids, which 'allow normal recovery'; further acceleration occurred 'as the ratio of ANY of these ingredients is increased up to 3-fold'. Ceramide did not uniquely occupy the '3' position — increasing cholesterol or fatty acid worked too. It also reports that glycosyl ceramides and sphingomyelin could substitute for ceramides, while phospholipids and cholesterol esters could not substitute for theirs. On humans it says only that 'similar preliminary results were obtained in damaged human skin' — a preliminary finding, not a finished-product clinical validation. The familiar three-component ceramide-dominant 3:1:1 label is later product shorthand, not a verbatim research result.Funding / interest: PubMed lists NIH/NIAMS grant AR19098. More materially: three of the four authors — Elias, Feingold and Thornfeldt — are named inventors on the EpiCeram patent, the ceramide-dominant 3:1:1 product this entry goes on to evaluate.
  5. van Zuuren EJ, Fedorowicz Z, Christensen R, Lavrijsen APM, Arents BWM. Emollients and moisturisers for eczema. Cochrane Database of Systematic Reviews. 2017;(2):CD012119.Tier 1Supports: The comparative moisturiser evidence base, including a Cochrane-computed itch estimate of MD 4.51 mm numerically FAVOURING petrolatum over the ceramide-dominant product.
  6. Miller DW, Koch SB, Yentzer BA, et al. An over-the-counter moisturizer is as clinically effective as, and more cost-effective than, prescription barrier creams in the treatment of children with mild-to-moderate atopic dermatitis. Journal of Drugs in Dermatology. 2011;10(5):531–537.Tier 2Supports: Three-week trial in 39 children aged 2–17 with mild-to-moderate atopic dermatitis, randomised 1:1:1 — THIRTEEN PER ARM — to a glycyrrhetinic-acid cream, a ceramide-dominant cream (EpiCeram, a 3:1:1 molar mixture) or an over-the-counter petrolatum ointment, applied three times daily. 'No statistically significant difference for any efficacy assessment was found between the three groups at each time point.' The petrolatum ointment was 'at least 47 times more cost-effective'. THE AUTHORS' OWN LIMITATION: 'The relatively small sample size of 39 subjects was not sufficient to establish OTC-Pet as superior treatment.' This was not designed as an equivalence or non-inferiority trial, so failing to detect a difference in 13 people per arm is not evidence that the products matched.
  7. Koppes SA, Charles F, Lammers LA, Frings-Dresen MH, Kezic S, Rustemeyer T. Efficacy of a cream containing ceramides and magnesium in the treatment of mild to moderate atopic dermatitis. Acta Dermato-Venereologica. 2016;96(7):948–953.Tier 2Supports: A specific ceramide-and-magnesium formulation in mild-to-moderate atopic dermatitis.Funding / interest: Funded by Omega Pharma.
  8. Andrew PV, Williams SF, Brown K, et al. Topical supplementation with physiological lipids rebalances skin barrier function. 2025.Tier 2Supports: 58 adults with dry, eczema-prone skin and a self-reported eczema history; a specific CeraVe cream improved selected 28-day measures against Cetraben.Funding / interest: Funded by L'Oréal, which owns CeraVe.
  9. Tanno O, Ota Y, Kitamura N, Katsube T, Inoue S. Nicotinamide increases biosynthesis of ceramides as well as other stratum corneum lipids. British Journal of Dermatology. 2000;143(3):524–531.In vitroTier 3Supports: TWO evidence layers, and this entry previously reported only the first. (1) Cultured normal human keratinocytes: nicotinamide increased ceramide synthesis 4.1–5.5-fold after six days, with glucosylceramide, sphingomyelin, free fatty acid and cholesterol synthesis also raised. (2) An IN-VIVO topical arm in dry skin, in which stratum-corneum ceramides and free fatty acids increased and TEWL decreased. The accessible abstract omits the human denominator, body site, formulation and effect sizes — so it supports an incompletely reported human signal, not a quantified facial claim, and certainly not the statement that no human stratum-corneum effect has been demonstrated.Funding / interest: Authored at Kanebo Ltd, a cosmetics manufacturer.
  10. Office for Product Safety and Standards. Regulation 1223/2009 and the Cosmetic Products Enforcement Regulations 2013: Great Britain. Updated 29 June 2026.Tier 1Supports: Cosmetic ingredient labelling requirements (GB, paragraph 99): an INCI list confirms declared ingredients in descending order but does not disclose exact percentages or lipid ratios.
  11. Office for Product Safety and Standards. Regulation 1223/2009 and the Cosmetic Products Enforcement Regulations 2013: Northern Ireland. Updated 29 June 2026.Tier 1Supports: The equivalent Northern Ireland labelling requirement (paragraph 95), in identical wording to the GB provision.