# The efficacy of hydrogen/oxygen therapy favored the recovery of omicron SARS-CoV-2 variant infection: results of a multicenter, randomized, controlled trial.
> オミクロン株SARS-CoV-2感染回復における水素/酸素吸入の有効性：多施設無作為化対照試験


## Abstract

This multicenter randomized controlled trial enrolled 64 patients with Omicron SARS-CoV-2 infection, randomly allocated to hydrogen/oxygen mixed gas inhalation (n=32) or oxygen-only inhalation (n=32). The hydrogen/oxygen group demonstrated a shorter viral shedding duration compared with the control group. Cumulative negative conversion rates showed a progressive increase from day 3 onward in the hydrogen/oxygen group. IL-6 concentrations declined by 22.8% from baseline, and lymphocyte counts rose to 61.1% of baseline values by day 3 in the hydrogen/oxygen group. A greater proportion of patients in the hydrogen/oxygen group exhibited resolution of pulmonary lesions on imaging. These findings indicate that molecular hydrogen inhalation may support immune recovery and reduce inflammatory markers in COVID-19 patients.

### Mechanism

Inhalation of hydrogen/oxygen mixed gas was associated with reduced IL-6 levels and restored lymphocyte counts, suggesting suppression of inflammatory cytokine signaling and enhancement of immune cell recovery, which may have contributed to faster viral clearance and pulmonary lesion resolution.

## Bibliographic

- **Authors**: Shi MM, Chen Y, Wang X, Zhang YJ, Cheng T, Chen H, et al.
- **Journal**: J Clin Biochem Nutr
- **Year**: 2023
- **PMID**: [37970554](https://pubmed.ncbi.nlm.nih.gov/37970554/)
- **DOI**: [10.3164/jcbn.23-32](https://doi.org/10.3164/jcbn.23-32)
- **PMC**: [PMC10636573](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10636573/)
- **Study type**: human randomized controlled trial
- **Delivery route**: inhalation
- **Effect reported**: positive

## Delivery context

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

## Safety notes

For inhalation applications of molecular hydrogen, the lower flammability limit (LFL) deserves careful handling. The classical 4% figure applies to closed-system mixtures; the practical inhalation-environment threshold is 10%. Even pure-hydrogen output (the UFL 75% paradox) passes through the flammable range at the air–gas boundary. High-concentration (66% / 100%) inhalers are documented in the Japanese Consumer Affairs Agency accident-information database and are not recommended.

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [LFL / UFL terminology](https://h2-papers.org/en/safety-notes/lfl-ufl-explained)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 37970554. https://h2-papers.org/en/papers/37970554
> **Source**: PubMed PMID [37970554](https://pubmed.ncbi.nlm.nih.gov/37970554/)