Ceramides
Ceramides — evidence, uses & status

Class: small_molecule
Synonyms: ceramide NP
ceramide AP
ceramide EOP
ceramide 3
ceramide 6-II
ceramide 1
phytosphingosine
sphingolipids
INCI: Ceramide NP
INCI: Ceramide AP
INCI: Ceramide EOP
Function tags: skin appearance (cosmetic)
barrier support
hydration
soothing (appearance of dryness)
Overall evidence grade: A
WADA prohibited: no
Last updated: 2026-07-08

In brief: Ceramides are the lipid molecules that make up roughly half of the skin's barrier by mass. Topical ceramide-dominant formulations have strong, well-replicated evidence for reducing transepidermal water loss and improving hydration — but with one crucial caveat: they work as barrier lipids only when combined with cholesterol and free fatty acids in balanced ratios (roughly 3:1:1). Ceramides alone in a poor vehicle underperform, and an incorrect lipid ratio can even temporarily disrupt the barrier. Properly formulated, they are a cornerstone barrier-repair ingredient, exceptionally gentle, and pregnancy-friendly.

## Identity

Ceramides are a family of **sphingolipids** — waxy lipid molecules made of a sphingosine (or phytosphingosine) backbone linked to a fatty acid. They are one of the three main lipid classes of the skin's outermost layer (the stratum corneum), alongside cholesterol and free fatty acids, and constitute approximately **50% of the barrier's lipid mass**. The stratum corneum contains 12+ distinct ceramide species, classified by molecular structure. The ones most used in skincare:

- **Ceramide NP** (formerly Ceramide 3) — the most abundant, the primary structural barrier lipid.
- **Ceramide AP** (Ceramide 6-II) — aids penetration; associated with anti-inflammatory activity.
- **Ceramide EOP** (Ceramide 1) — an unusual ester-linked omega-hydroxy ceramide critical for organising the lamellar (layered) structure of the barrier; notably depleted in eczema.

## Development & history

- Identified as key stratum corneum lipids through skin-barrier research from the 1980s onward, as the "brick and mortar" model of the stratum corneum (corneocyte "bricks" in a lipid "mortar") became established.
- Recognition that ceramide *depletion* drives dryness and barrier dysfunction (documented in atopic dermatitis and aged skin) motivated their use in barrier-repair cosmetics.
- Synthetic "skin-identical" ceramides and pseudo-ceramides were developed to allow stable cosmetic formulation.
- Now a cornerstone of the "barrier repair" category — the dominant skincare trend of the mid-2020s as the earlier "more actives" culture gave way to gentler, barrier-first routines.

## Mechanism (as proposed)

The stratum corneum works as a permeability barrier because its lipids form organised **lamellar (multi-layer) sheets** between the skin cells, sealing water in and irritants out. Ceramides are the dominant structural component of those sheets. When ceramide content drops — through age, harsh products, over-exfoliation, or conditions like eczema — the lamellar structure is disrupted, transepidermal water loss rises, and skin becomes dry and reactive.

Topically applied ceramides can integrate into this lipid matrix and, in ceramide-deficient skin, help restore its organisation and reduce water loss. The single most important formulation principle: **ceramides do not act alone.** A healthy barrier is roughly 50% ceramides, 25% cholesterol, and 15% free fatty acids by lipid mass (commonly formulated near a 3:1:1 ceramide:cholesterol:fatty-acid ratio). Studies show that applying lipids in a physiologically balanced ratio restores the barrier, whereas an incorrect ratio can *delay* recovery or temporarily worsen it. This is why ceramide efficacy is a formulation property, not just an ingredient-presence property — the reason two products both listing "ceramides" can perform very differently.

Niacinamide is worth noting as a complementary partner: it boosts the skin's own synthesis of ceramides and fatty acids, so the two are frequently and sensibly combined.

Evidence grades by outcome:
outcome: Barrier repair / TEWL reduction (ceramide-dominant formula)
grade: A
base: Multiple RCTs and controlled trials; multicenter study n=312 (4-week ceramide-enriched regimen, SCORAD −61.2%); 2019 qualitative review of 12 clinical studies; 2024-2025 controlled trials showing structurally skin-identical ceramide NP/AP/EOP formulations reduce transepidermal water loss and raise stratum corneum lipid content
effect: Measurable reduction in transepidermal water loss and improved skin hydration, typically within 1–2 weeks of consistent twice-daily use
caveat: Efficacy depends heavily on formulation — ceramides work as barrier lipids only when combined with cholesterol and free fatty acids in balanced ratios (see mechanism). Isolated ceramides in a poor vehicle underperform.
outcome: Adjunct in atopic dermatitis / eczema-prone dry skin (appearance & comfort)
grade: A
base: Multiple interventional studies in mild-to-moderate atopic dermatitis; ceramide-dominant formulations achieve ~45–60% clinical success (IGA clear/almost clear) in 3–8 week studies; physiological-lipid formulations (MVE+GL) outperform simple emollients in barrier integrity
effect: Reduced dryness, itch, and roughness; improved barrier integrity as an adjunct to (not replacement for) medical treatment
caveat: Atopic dermatitis is a medical condition — ceramide cosmetics are barrier-supportive adjuncts, not treatments. Persistent or severe cases need a dermatologist.
outcome: Aged / menopausal skin barrier (hydration & smoothness appearance)
grade: B
base: Clinical research in elderly individuals showing high-concentration ceramide formulations improve hydration and barrier function; consistent with the age-related decline in endogenous ceramide content
effect: Improved skin hydration and the appearance of smoother skin
caveat: Fewer large trials specific to aged skin than to atopic dermatitis; effect is barrier/hydration-mediated, not collagen-building
outcome: Oral ceramide supplementation (skin hydration)
grade: C
base: Small open-label studies (e.g. rice-derived ceramide supplementation n=50) suggesting hydration benefit; evidence far thinner than for topical
effect: Possible modest hydration improvement
caveat: Oral use is outside cosmetic scope and much less established than topical. Not relevant to Vallydia's sellable topical products.

Legal status:
region: INT
status: Lawful cosmetic ingredient
note: Topical ceramides (ceramide NP, ceramide AP, ceramide EOP, and related sphingolipids and pseudo-ceramides) are lawful cosmetic ingredients globally, including EU (Regulation (EC) 1223/2009). CosIng-listed by species. No concentration ceiling. Naturally present in human skin; widely used at 0.05–2% depending on species and formulation. Not a restricted or controlled substance in any major market.

Cosmetic claims:
allowed: supports the appearance of a healthy, resilient-looking skin barrier
helps skin look and feel hydrated and comfortable
for the appearance of smoother, less-flaky skin
helps reduce the look of dryness and tightness
replenishes skin's feel of moisture
forbidden: repairs the skin barrier
treats eczema
treats atopic dermatitis
heals damaged skin
restores the lipid barrier
reduces inflammation
anti-inflammatory
cures dryness

Note: Ceramides are lawful cosmetic ingredients worldwide and among the best-tolerated of all skincare actives (naturally present in skin, no documented pregnancy concerns). Vallydia uses them in barrier-support formulations designed with the cholesterol and fatty-acid partners that the evidence shows are necessary for function. Reference science below includes medical (atopic dermatitis) studies for mechanism context; only cosmetic appearance/comfort use is relevant to the sellable product.

Sources:
Elias PM, Wakefield JS. Mechanisms of abnormal lamellar body secretion and the dysfunctional skin barrier in patients with atopic dermatitis. J Allergy Clin Immunol. 2014.
Meckfessel MH, Brandt S. The structure, function, and importance of ceramides in skin and their use as therapeutic agents in skin-care products. J Am Acad Dermatol. 2014; 71(1):177-84.
Draelos ZD. The effect of ceramide-containing skin care products on eczema resolution duration. Cutis. 2008.
Spada F, Barnes TM, Greive KA. Skin hydration is significantly increased by a cream formulated to mimic the skin's own natural moisturizing systems. Clin Cosmet Investig Dermatol. 2018.
Qualitative review of 12 clinical studies on ceramide-containing formulations in barrier repair (2019).
Multicenter study (n=312) — ceramide-enriched regimen; SCORAD reduction reference cited above.