# Molecular hydrogen as a preventive and therapeutic medical gas: initiation, development and potential of hydrogen medicine.
> 水素ガスの医療応用：水素医学の発端・発展・将来展望に関するレビュー


## Abstract

Molecular hydrogen (H2), long regarded as biologically inert, was shown to react with potent oxidants such as hydroxyl radicals within cells, fundamentally revising that assumption. H2 diffuses rapidly into tissues and cells while remaining mild enough to leave normal redox signaling intact, suggesting a low adverse-effect profile. Multiple administration routes have been investigated, including gas inhalation, oral intake of hydrogen-dissolved water, intravenous or intraperitoneal hydrogen-rich saline, hydrogen baths, and ocular instillation. Accumulated evidence indicates that H2 reduces oxidative stress both through direct scavenging of strong oxidants and through modulation of gene expression, resulting in anti-inflammatory, anti-apoptotic, and energy-metabolism-enhancing effects. Beyond extensive animal model data, numerous clinical investigations have been conducted or are ongoing across a wide range of conditions, positioning H2 as a candidate with broad applicability and a favorable safety profile.

### Mechanism

H2 directly scavenges potent oxidants including hydroxyl radicals and indirectly modulates gene expression to exert anti-inflammatory, anti-apoptotic, and energy-metabolism-enhancing effects without disrupting physiological redox signaling.

## Bibliographic

- **Authors**: Ohta S
- **Journal**: Pharmacol Ther
- **Year**: 2014
- **PMID**: [24769081](https://pubmed.ncbi.nlm.nih.gov/24769081/)
- **DOI**: [10.1016/j.pharmthera.2014.04.006](https://doi.org/10.1016/j.pharmthera.2014.04.006)
- **Study type**: review
- **Delivery route**: mixed routes
- **Effect reported**: not assessed

## Delivery context

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident database and are not recommended).

## Safety notes

This study combines multiple delivery routes. As a general principle, the most efficient route for routine hydrogen intake is inhalation. Inhalation carries explosion risk (empirical LFL of 10%; high-concentration devices are documented in the Consumer Affairs Agency accident 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)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 24769081. https://h2-papers.org/en/papers/24769081
> **Source**: PubMed PMID [24769081](https://pubmed.ncbi.nlm.nih.gov/24769081/)