What is skin hydration?

Skin hydration is the water content of the skin, most often operationalised in research as the water content of the stratum corneum and the epidermis, together with the barrier function that governs water movement through it. It is not a single molecule or a single receptor target; it is a physiological state, and the literature measures it with instruments rather than with a formal chemical identifier. The most common instrumental endpoints are corneometry (electrical capacitance of the skin surface, reported in arbitrary units), transepidermal water loss (TEWL, reported in g/m²/h), and, in some protocols, elasticity and barrier-function measurements taken alongside them [2][6]. Because hydration is a state rather than a substance, the research literature is organised around interventions — dietary peptides, topical emollients, injectable fillers and boosters, and device-assisted procedures — and around the models in which each was tested.

The mechanistic work in this area centres on the epidermal barrier and the dermal extracellular matrix: corneocyte water-binding within the stratum corneum, lipid-mediated barrier integrity, and the collagen and hyaluronan network of the dermis that retains water and supports mechanical properties [4][11].

Research Studies

Ergothioneine and oxidative-stress and skin-hydration endpoints in healthy adults

A randomised, double-blind, placebo-controlled trial is evaluating a branded ergothioneine ingredient in healthy adults aged 40 to 65 years. Participants receive either the ingredient or a matching placebo once daily for 12 weeks. The primary objective is the effect on biomarkers associated with oxidative stress and healthy aging; secondary objectives include skin elasticity, skin hydration, inflammatory biomarkers and overall safety [1]. This is a registered protocol; the hydration finding is a secondary endpoint rather than a completed result.

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

In hairless mice with oxazolone-induced atopic dermatitis-like skin, a collagen tripeptide-containing preparation (AP collagen peptide) was evaluated for effects on skin hydration and inflammatory responses. Skin hydration and transepidermal water loss were among the measured outcomes in a model characterised by impaired barrier function and Th2-mediated immune responses [2]. This is an animal model; the findings are not human data.

Fish collagen hydrolysates and wound healing in a patent review

A patent review of fish collagen hydrolysates in wound healing reports that collagen peptides derived from collagen hydrolysis have attracted interest as bioactive materials in advanced dressings, and that fish collagen has gained prominence relative to traditional sources on the basis of its profile [3]. The review is a patent-landscape document; it summarises claimed and disclosed applications rather than reporting a controlled hydration trial.

Oral collagen supplementation and skin, hair, nail and wound-healing outcomes in humans

A narrative review of human evidence on oral collagen supplementation reports that collagen is a key structural protein of skin, contributing to mechanical strength, elasticity and hydration, and that collagen peptides have drawn interest as a nutritional strategy. The same review states that the evidence for effectiveness across skin, hair, nail and wound-healing outcomes is heterogeneous [4]. The review's own framing is that the human evidence base is mixed, not uniform.

L-carnosine-containing hyaluronate injection and facial skin hydration and brightness

A randomised, controlled, evaluator-blinded trial examined an L-carnosine-containing hyaluronate injection for facial skin hydration and brightness [5]. The evidence block for this record supplies the trial design and the stated endpoints; it does not supply numerical outcomes.

Panthenol, niacinamide and dipotassium glycyrrhizate formulation in xerosis

In a 28-day randomised, intra-individual, split-leg, untreated-controlled trial, subjects with xerosis cutis applied a topical formulation containing panthenol, niacinamide and dipotassium glycyrrhizate twice daily to one pretibial area, with the contralateral leg left untreated as control. Xerosis cutis is characterised by impaired epidermal barrier function, increased transepidermal water loss and reduced hydration. The trial assessed efficacy, tolerability and subjective perception of hydration and barrier function [6]. The split-leg design means each participant served as their own control.

Ariessence Pure PDGF+ after ablative laser, compared with an emollient control

A multi-centre post-market cosmetic evaluation is studying a viscous leave-on topical solution applied to the full face after an ablative laser procedure, compared with an emollient control. The product is described as intended for use following non-medical cosmetic procedures to enhance comfort and maintain skin hydration; the study evaluates procedure tolerability and appearance of the skin [7]. This is a post-market cosmetic evaluation, not a mechanistic study.

Cellbooster Shape in healthy subjects with facial signs of skin aging

A post-market clinical investigation is evaluating a CE-marked hyaluronic-acid-based superficial epidermis/dermis injection filler and skinbooster consisting of non-crosslinked HA with L-carnitine and vitamin C, designed for reducing local puffiness by improving microcirculation and hydration. Healthy subjects with facial signs of skin aging receive a three-session treatment with follow-up over 70 days after the initial injection session, with several objective skin measurements taken [8].

Comparison of study designs and hydration-relevant endpoints

Supporting formulation and materials work

Several records in this evidence set address formulation behaviour rather than a hydration endpoint in a defined population. A study of hydroxyethyl cellulose as a functional polymer additive reports the development of a structurally stable skin-brightening moisturising cream using niacinamide as the active ingredient, with physicochemical properties and performance systematically characterised [9]. A pilot study of a hydrogel facial mask based on poly(N-vinyl pyrrolidone) and poly(ethylene glycol) investigated safety, tolerability and functional performance, including hydration and barrier function, in sensitive skin over long-term use [10]. A spectroscopic and molecular-interaction analysis of pentapeptide-18 frames skin aging around progressive breakdown of the dermal extracellular matrix, with reduced collagen and elastin synthesis and wrinkle formation from repetitive facial muscle movement [11]. A retrospective study reports clinical outcomes of intense pulsed light combined with non-crosslinked sodium hyaluronate, tranexamic acid and vitamin C mesotherapy for facial photoaging, in a context where single-modality treatments rarely address pigmentary, vascular and dermal matrix changes concurrently [12]. These are supporting references; none is a controlled hydration trial in a general population.

If you are reading this for personal health reasons

The materials described on this page are supplied for laboratory research use only, and we do not provide dosing information or medical guidance of any kind. Nothing here is a recommendation to use any compound, formulation or procedure on yourself. If you are considering a compound or treatment for your own health or skin, speak to a licensed clinician.

Sources

• [1] NVTIA® Ergothioneine for Healthy Aging and Skin Health — https://clinicaltrials.gov/study/NCT07750002
• [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] Fish Collagen Hydrolysates in Wound Healing: A Patent Review — https://europepmc.org/article/PMC/PMC13482881
• [4] Dietary Collagen Supplementation as a Strategy for Skin Health: A Narrative Review of Clinical Effects on Skin, Hair, Nails, and Wound Healing — https://europepmc.org/article/PMC/PMC13364118
• [5] Efficacy and Safety of L‐Carnosine‐Containing Hyaluronate Injection for Facial Skin Hydration and Brightness: A Randomized, Controlled, Evaluator‐Blinded Trial — https://europepmc.org/article/PMC/PMC13323873
• [6] Efficacy of a Topical Formulation on Skin Hydration and Barrier Function in Individuals With Xerosis: A 28-Day Randomized, Split-Leg, Untreated-Controlled Trial — https://europepmc.org/article/PMC/PMC13158435
• [7] Post-market Cosmetic Evaluation of Ariessence™ Pure PDGF+ Following Ablative Laser — https://clinicaltrials.gov/study/NCT07718347
• [8] Effectiveness and Safety of Cellbooster Shape in Healthy Subjects — https://clinicaltrials.gov/study/NCT07636512
• [9] Intermolecular network reorganization induced by hydroxyethyl cellulose enables structurally stable niacinamide-based soft matter systems — https://pubmed.ncbi.nlm.nih.gov/42595163/
• [10] Hydrogel facial mask for sensitive skin: A pilot study of long-term effects on hydration, barrier function and mechanical properties — https://europepmc.org/article/PMC/PMC13448365
• [11] Pentapeptide-18 as an anti-aging candidate: Spectroscopic characterization and molecular interaction analysis — https://pubmed.ncbi.nlm.nih.gov/41722287/
• [12] Clinical outcomes of intense pulsed light combined with non-crosslinked sodium hyaluronate, tranexamic acid, and vitamin C mesotherapy for facial photoaging: a retrospective study — https://pubmed.ncbi.nlm.nih.gov/41489066/