Journal September 26, 2026 6 min read

How is Transepidermal Water Loss Measured?

Transepidermal water loss (TEWL) is quantified in vivo using non-invasive evaporimetry, most commonly open-chamber or closed-chamber devices. This page describes the measurement principles and how TEWL is applied as an e

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What is transepidermal water loss?

Transepidermal water loss (TEWL) is the passive diffusion of water vapour from the dermis through the stratum corneum to the external environment. It is expressed as a rate of mass flux per unit area, typically in grams per square metre per hour (g/m²/h). TEWL is not a compound but a physiological parameter used to assess skin barrier integrity. In research settings, it is measured with evaporimeters, also called TEWL meters, which quantify the water vapour gradient above the skin surface.

The measurement centres on the skin barrier function of the stratum corneum, particularly the extracellular lipid matrix and corneocyte envelope, which regulate water flux. Disruption of this barrier increases TEWL, making it a standard endpoint in studies of xerosis, atopic dermatitis, and topical formulations.

Research Studies

AP collagen peptides and skin hydration in a mouse model of oxazolone-induced atopic dermatitis

In a study using hairless mice with oxazolone-induced atopic dermatitis-like lesions, researchers evaluated AP collagen peptide (APCP), which contains collagen tripeptide (CTP), for effects on skin hydration and inflammatory responses. Skin hydration and transepidermal water loss were among the parameters assessed. The model is animal-only; findings do not directly translate to human use [2].

Topical formulation and barrier function in individuals with xerosis

A 28-day randomized, split-leg, untreated-controlled trial tested a topical formulation containing panthenol, niacinamide, and dipotassium glycyrrhizate in subjects with xerosis cutis. The study measured TEWL alongside skin hydration and tolerability. One pretibial area received the test emollient twice daily; the contralateral leg served as an untreated control. Assessments were performed at baseline and at subsequent time points [3].

Emulgel and TEWL in paediatric atopic dermatitis

In a randomized, self-controlled trial, 57 children aged 2–14 with atopic dermatitis applied an emulgel containing hyaluronic acid, glycerol, grape seed oil, Calendula officinalis, aloe vera, and sh-oligopeptide-1 to one forearm twice daily for 10 days; the other forearm served as control. Skin barrier parameters including TEWL, stratum corneum hydration, erythema, and pH were measured [5].

Vitamin K2 cream and TEWL 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. The study assessed whether the test cream improved skin hydration (Corneometer), reduced TEWL (Vapometer), and enhanced elasticity and firmness (Cutometer) compared to a control cream. Wrinkle severity was also assessed via optical imaging [7].

NPQ Plus supplementation and skin health in healthy adults

A single-arm, open-label study involving 55 participants evaluated NPQ Plus, a multi-component nutraceutical containing polyphenols (Oligonol®), nicotinamide mononucleotide (NMN; RevAge®), pyrroloquinoline quinone (PQQ; PureQQ®), coenzyme Q10, and a trace mineral complex. Subjects consumed one sachet daily for 12 weeks. Assessments at baseline and Weeks 4, 8, and 12 included skin health parameters, though TEWL was not specified in the available summary [4].

Oral collagen peptides and skin properties in women with facial wrinkles

A randomized, double-blind, parallel-group trial enrolled 68 healthy women aged 35–65 with visible facial wrinkles. Participants received either an active control or avvera™ for daily oral intake. The study evaluated age-associated skin beauty parameters. TEWL was not listed among the primary outcomes in the summary [6].

Mushroom extract formulation during breast radiotherapy

A study assessed a mushroom extract-containing topical cosmetic formulation in women receiving radiotherapy to the breast after breast-conserving surgery. Participants were randomized to the investigational formulation or usual moisturizing care, applied twice daily from approximately 15 days before radiotherapy through 1 month after. Skin condition was assessed, but TEWL was not specified as an endpoint in the available description [8].

Vernix caseosa retention and atopic dermatitis prevention

A clinical trial is investigating whether retention of vernix caseosa—the white, creamy substance covering newborn skin at birth—can prevent atopic dermatitis. The study focuses on skin-barrier integrity and the skin microbiome in early life. TEWL is not mentioned as a measured outcome in the summary [1].

Reference-only studies

Several additional investigations have employed TEWL or related barrier assessments. A multicenter study evaluated temporally optimized antioxidant serums for daytime defense and nighttime repair in sensitive skin [9]. A randomized controlled trial examined a comprehensive topical regimen incorporating niacinamide, Pro-Xylane, and panthenol after PicoWay laser, assessing skin barrier repair and anti-aging effects [10]. A pilot study investigated long-term effects of a hydrogel facial mask on hydration, barrier function, and mechanical properties in sensitive skin [11]. A real-world longitudinal study explored clinical outcomes of a digital standardized skin care regimen in acne-rosacea comorbidity [12]. These reports support the broader context of TEWL measurement but are not the focus of this page.

How is TEWL measured?

TEWL is measured using evaporimetry, which quantifies the water vapour flux from the skin surface. The two main device types are open-chamber and closed-chamber systems. Open-chamber devices maintain a continuous airflow over the skin and measure the vapour gradient; closed-chamber devices seal a small volume against the skin and measure the rate of humidity increase. Both provide TEWL in g/m²/h. Measurements are typically taken under controlled environmental conditions (temperature and relative humidity) and after acclimatization. Common instruments include the Tewameter® and Vapometer®. The table below compares key features.

Feature	Open-chamber	Closed-chamber
Principle	Measures vapour gradient in open air	Measures humidity increase in sealed volume
Typical devices	Tewameter®	Vapometer®
Units	g/m²/h	g/m²/h
Considerations	Affected by ambient airflow	Less affected by ambient airflow

In research, TEWL is often combined with corneometry (for stratum corneum hydration) and other biophysical measurements to assess barrier function. The studies cited above illustrate its application in both human clinical trials and animal models.

If you are reading this for personal health reasons

The materials and information on this page are provided for laboratory research purposes only. We do not provide dosing, medical guidance, or treatment advice. Anyone considering a compound or measurement for themselves should consult a licensed clinician.