What does the research say about transepidermal water loss?
Transepidermal water loss (TEWL) is the passive diffusion of water vapour through the stratum corneum, measured in g/m²/h. This page summarises what controlled trials and animal models report about interventions studied
Transepidermal water loss (TEWL) is the passive flux of water vapour diffusing from the hydrated viable epidermis through the stratum corneum and into the surrounding air. It is not sweat, and it is not insensible perspiration from the sweat glands; it is a diffusive gradient across the cornified layer, and it is reported in grams of water per square metre per hour (g/m²/h). Synonyms in the literature include insensible water loss of the skin and, less precisely, barrier water loss. TEWL is a measurement, not a compound: it has no sequence, no formula and no molecular weight. It is the standard instrumental readout for epidermal barrier function, and it is typically paired with stratum corneum hydration (SCH), erythema and surface pH when a formulation or supplement is being characterised. Because the value depends on ambient temperature, relative humidity, probe placement and acclimatisation time, absolute numbers are only comparable within a study, not across studies.
The biology the work centres on is the stratum corneum permeability barrier — the corneocyte lipid matrix, filaggrin processing and the tight-junction and lipid-processing machinery of the upper epidermis — with barrier integrity in atopic dermatitis additionally framed through Th2-mediated immune signalling.
Research Studies
Panthenol, niacinamide and dipotassium glycyrrhizate in adults with xerosis cutis
A 28-day randomised, intra-individual, split-leg trial enrolled subjects with xerosis cutis and had each participant apply a topical formulation containing panthenol, niacinamide and dipotassium glycyrrhizate twice daily to one pretibial area, leaving the contralateral leg untreated as the control [3]. Assessments covered hydration, barrier function, tolerability and subjective perception. The split-leg design is the relevant methodological point: because the untreated leg belongs to the same person, the comparison is not confounded by between-subject variation in baseline TEWL.
Hyaluronic acid, glycerol and sh-oligopeptide-1 emulgel in paediatric atopic dermatitis
A randomised, self-controlled trial in 57 children aged 2–14 applied an emulgel containing hyaluronic acid, glycerol, grape seed oil, Calendula officinalis, aloe vera and sh-oligopeptide-1 — a synthetic epidermal growth factor — twice daily for 10 days to one forearm, with the other forearm serving as control [5]. TEWL, stratum corneum hydration, erythema and pH were measured as barrier parameters. The population here is children with atopic dermatitis, and the observation window is short.
AP collagen peptide in an oxazolone-induced mouse model
This work is animal-only. AP collagen peptide, which contains collagen tripeptide, was evaluated in hairless mice with oxazolone-induced atopic-dermatitis-like skin, with skin hydration and transepidermal water loss as endpoints alongside inflammatory responses [2]. The authors note that collagen tripeptide has been reported to improve skin hydration and barrier function and that its effects under conditions of established barrier dysfunction had not been fully established. Findings in an oxazolone mouse model do not transfer directly to human skin.
Vitamin K2 (MK-7) cream in a split-face/neck trial
A clinical trial evaluated a facial and neck cream containing vitamin K2 (MK-7) in 36 female participants aged 35–60 with concerns of facial dryness, dullness, laxity and neck lines, comparing the test cream against a control cream [7]. TEWL was measured by Vapometer, hydration by Corneometer, and elasticity and firmness by Cutometer, with wrinkle severity assessed by rapid optical imaging. The design is split-face/neck, so the control is the participant's own contralateral side.
Two oral bioactive collagen peptides in women with facial wrinkles
A randomised, double-blind, parallel-group trial enrolled 68 healthy women aged 35–65 with noticeable facial wrinkles, allocated 1:1 to an active control or to avvera™; one participant in the active control group withdrew for personal reasons and was excluded, leaving 67 in the final analysis [6]. The stated objective was whether daily oral intake of a collagen peptides supplement improved age-associated skin beauty parameters. This is an oral intervention, so any barrier-related readout sits downstream of digestion and systemic distribution rather than at the skin surface.
NPQ Plus in healthy adults with skin concerns
A single-arm, open-label, prospective interventional study gave 55 participants one sachet of NPQ Plus daily for 12 weeks, with assessments at baseline and at weeks 4 and beyond [4]. NPQ Plus is a multi-component nutraceutical containing polyphenols (Oligonol®), nicotinamide mononucleotide (NMN; RevAge®), pyrroloquinoline quinone (PQQ; PureQQ®), coenzyme Q10 and a trace mineral complex (Ioniplex). The absence of a control arm is the limitation to keep in view when reading any skin-health endpoint from this study.
Mushroom extract formulation during breast radiotherapy
A trial randomised women receiving radiotherapy to the breast after breast-conserving surgery to an investigational mushroom extract-containing topical cosmetic formulation or to usual moisturising cosmetic care [8]. The product was applied to intact breast skin twice daily, starting roughly 15 days before radiotherapy, continuing through the approximately 3-week treatment period, and ending one month after radiotherapy, with application withheld in the 3–4 hours before each session. Skin condition was assessed before and during the radiotherapy course.
Vernix caseosa retention in newborns
A registered trial addresses primary prevention of atopic dermatitis — prevention before disease onset — through retention of vernix caseosa, the white, creamy substance covering newborn skin at birth that forms during the last trimester [1]. The rationale given is that genetic and environmental factors, particularly those relating to skin-barrier integrity and the skin microbiome in early life, contribute to atopic dermatitis, which affects up to one in five children worldwide. This is a prevention question in newborns, not a TEWL measurement study in adults.
Comparison of study designs and populations
| Intervention | Population / model | Design | Barrier readout |
|---|---|---|---|
| Panthenol, niacinamide, dipotassium glycyrrhizate [3] | Adults with xerosis cutis | Randomised, split-leg, untreated control, 28 days | Hydration and barrier function |
| Emulgel with HA, glycerol, sh-oligopeptide-1 [5] | Children aged 2–14 with AD | Randomised, self-controlled, 10 days | TEWL, SCH, erythema, pH |
| AP collagen peptide [2] | Hairless mice, oxazolone-induced AD-like skin | Animal model | Skin hydration and TEWL |
| Vitamin K2 (MK-7) cream [7] | Women 35–60 | Split-face/neck, control cream | TEWL (Vapometer), Corneometer, Cutometer |
| Oral collagen peptides [6] | Women 35–65 with facial wrinkles | Randomised, double-blind, parallel-group | Age-associated skin parameters |
| NPQ Plus [4] | Healthy adults with skin concerns | Single-arm, open-label, 12 weeks | Skin health, antioxidant status |
| Mushroom extract cosmetic [8] | Women receiving breast radiotherapy | Randomised, usual-care control | Skin condition during radiotherapy |
Several further clinical investigations report barrier-related endpoints without being built around TEWL as a primary question. A multicentre investigation of temporally optimised day and night antioxidant serums framed its rationale around oxidative stress, barrier dysfunction and disrupted skin biorhythms in sensitive skin [9]. A randomised controlled study examined a comprehensive topical regimen incorporating niacinamide, Pro-Xylane and panthenol after PicoWay laser, asking whether the combination delivers synergistic barrier-repair and anti-aging effects [10]. A pilot study characterised the long-term hydration, barrier-function and mechanical-property effects of a hydrogel facial mask based on poly(N-vinyl pyrrolidone) and poly(ethylene glycol) in sensitive skin [11]. A real-world longitudinal study used cross-lagged and mediation analyses to examine associations between a digital standardised skin care regimen and outcomes in co-occurring acne and rosacea [12].
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Sources
- [1] Retention of Vernix Caseosa in Newborns for Primary Prevention of Atopic Dermatitis — https://clinicaltrials.gov/study/NCT07333378
- [2] Potential Supportive Effects of AP Collagen Peptides on Skin Hydration in a Mouse Model of Oxazolone-Induced Atopic Dermatitis — https://europepmc.org/article/PMC/PMC13526892
- [3] Efficacy of a Topical Formulation on Skin Hydration and Barrier Function in Individuals With Xerosis — https://europepmc.org/article/PMC/PMC13158435
- [4] NPQ Plus Supplementation for Skin Health and Antioxidant Status — https://clinicaltrials.gov/study/NCT07703215
- [5] Update on the Research of an Emulgel for the Effective Treatment of Atopic Dermatitis: Clinical Investigation in Children — https://europepmc.org/article/PMC/PMC12652510
- [6] Clinical Effects of Two Oral Bioactive Collagen Peptides On Skin Properties and Aging Hallmarks — https://clinicaltrials.gov/study/NCT07302789
- [7] The Skin Anti-Aging Effects of Vitamin K2 (MK-7): a Clinical Split-Face/Neck Trial — https://clinicaltrials.gov/study/NCT07403942
- [8] Effect of a Mushroom Extract-Containing Topical Cosmetic Formulation During Breast Radiotherapy — https://clinicaltrials.gov/study/NCT07755553
- [9] Temporally Optimized Antioxidant Serums for Daytime Defense and Nighttime Repair — https://pubmed.ncbi.nlm.nih.gov/42728530/
- [10] Skin barrier repairing and anti-aging effects of a comprehensive topical regimen after PicoWay laser — https://europepmc.org/article/PMC/PMC13538206
- [11] Hydrogel facial mask for sensitive skin: a pilot study — https://europepmc.org/article/PMC/PMC13448365
- [12] Clinical outcomes associated with a digital standardized skin care regimen in acne-rosacea comorbidity — https://pubmed.ncbi.nlm.nih.gov/42455099/