Molecular Hydrogen for Outpatients with COVID-19 (Hydro-COVID): A Phase 3 Randomised, Triple-Blinded, Pragmatic, Placebo-Controlled, Multicentre Trial
Gaboreau Y et al. · J Clin Med. 2024;13(15):4308.
Study at a glance
Human
Outpatients with mild-to-moderate laboratory-confirmed acute COVID-19 and at least one risk factor
One H₂-producing tablet in 250 mL water twice daily; 500 mL/day · The main article identifies Drink HRW tablets but does not report a verified delivered H₂ concentration or total H₂ dose.
21 days; primary outcome at day 14 and safety follow-up at day 30
HRW did not reduce clinical worsening: 46.1% versus 43.5%; hazard ratio 1.09, 90% CI 0.90–1.31. Adverse events were similar: 27.0% versus 26.2%.
This large trial reported a clear null primary result. Drink HRW supplied part of the study funding; authors declared no trial-related conflicts. Acute COVID-19 is distinct from Long COVID.
What kind of evidence is this?
Human
Phase 3 randomized triple-blind placebo-controlled multicenter trial
Respiratory health
H₂-rich water
Information not yet classified
Some editorial classification fields are still pending. The source-reported outcomes and result are shown below; Hydrogenology does not infer a positive or negative signal from prose automatically.
Methods
Outpatients with mild-to-moderate laboratory-confirmed acute COVID-19 and at least one risk factor
700 randomized; 675 included in day-30 follow-up
21 days; primary outcome at day 14 and safety follow-up at day 30
One H₂-producing tablet in 250 mL water twice daily; 500 mL/day
H₂ dissolved in water — H₂ only, not Brown’s gas.
The main article identifies Drink HRW tablets but does not report a verified delivered H₂ concentration or total H₂ dose.
Matched effervescent placebo tablets in the same water volume, alongside usual care
Outcomes and reported result
Clinical worsening, oxygen use, hospitalization, death, symptom resolution, persistent symptoms and adverse events
HRW did not reduce clinical worsening: 46.1% versus 43.5%; hazard ratio 1.09, 90% CI 0.90–1.31. Adverse events were similar: 27.0% versus 26.2%.
Methods, primary and safety results, registration, funding and conflict statement checked in the free full text.
A reported association, difference or mechanism is not automatically a clinical benefit.
Limitations and applicability
This large trial reported a clear null primary result. Drink HRW supplied part of the study funding; authors declared no trial-related conflicts. Acute COVID-19 is distinct from Long COVID.
At-risk outpatients with acute mild-to-moderate COVID-19 under the trial conditions.
No single-study GRADE certainty rating is assigned. Read how records and evidence assessments are prepared.
Sources and record status
PMID: 39124575 · DOI: 10.3390/jcm13154308
Open-access article.
Free full text on PMC and publisher page; identifiers cross-checked in PubMed.
10 August 2026
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