Electrolytically generated hydrogen warm water cleanses the keratin-plug-clogged hair-pores and promotes the capillary blood-streams, more markedly than normal warm water does.
Tanaka Y, Saitoh Y, Miwa N. · 2018.
What kind of evidence is this?
Human
Small uncontrolled within-person physiological study
Skin, wound and aging research
Other forms
Exploratory positive surrogate signal.
Short-term physiological and cosmetic surrogate outcomes.
Methods at a glance
Healthy adult volunteers using hydrogen-rich warm water.
Small volunteer sample; outcome-specific participant counts are reported in the article.
Acute hand immersion and a seven-day bathing assessment.
Hand immersion or bathing in electrolytically generated hydrogen-rich warm water.
H₂ dissolved in warm bath water.
Water was maintained around 40°C; dissolved-H₂ conditions were measured under the article protocol.
Not applicable.
No oxygen was co-delivered.
Normal warm water and pre-exposure measurements.
Outcomes and reported result
Fingertip capillary flow, skin moisture and microscopy of keratin plugs.
The article reports higher capillary-flow, skin-moisture and pore-cleansing measures after hydrogen warm water than normal warm water at selected observations.
The full article was checked for methods, intervention details, outcomes, positive and null findings, funding and conflicts. This record does not imply medical efficacy.
A reported association, difference or mechanism is not automatically a clinical benefit. Null findings, outcome type, study design and precision all matter.
Cautions and applicability
Small uncontrolled or incompletely randomized study with cosmetic surrogates and possible temperature or electrolysis-property confounding.
Healthy volunteers under the reported bathing conditions only.
ROBINS-I — preliminary
Serious concerns
Small sample, unclear allocation/blinding and multiple image-derived surrogate outcomes create serious concerns.
Selection and allocation checked · Confounding and co-interventions remain possible · Missing observations checked where reported · Outcome measurement varies by endpoint · Selective reporting cannot be excluded
No single-study GRADE certainty rating is assigned. Certainty is assessed by important outcome across a complete eligible evidence set, not by attaching a final grade to one source.
Sources and record status
PMID: 29770191 · DOI: 10.4103/2045-9912.229598
A free full article is available through PubMed Central.
Official PubMed Central full article and PubMed bibliographic record; source identity, methods, intervention, results, funding and conflicts checked 10 August 2026.
2026-08-10