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Molecular Hydrogen: A Promising Adjunctive Strategy for the Treatment of the COVID-19.

COVID-19に対する分子状水素の補助的アプローチ：炎症制御と治療標的の検討

review inhalation not assessed

Abstract

COVID-19, caused by SARS-CoV-2, is characterized by an exaggerated inflammatory response in which cytokine storms drive disease severity. This review examines the pathophysiological mechanisms underlying COVID-19 and surveys existing evidence showing that molecular hydrogen suppresses excessive inflammatory cells and mediators across a range of critical illnesses. In China, inhalation of a hydrogen-oxygen mixed gas was investigated as an adjunctive intervention for COVID-19 patients and was subsequently incorporated into national clinical guidelines. The review further evaluates the biological plausibility of hydrogen as an adjunct for COVID-19, identifying potential mechanistic targets including oxidative stress, inflammatory signaling, and immune dysregulation, and discusses the feasibility of hydrogen-based strategies in this context.

Mechanism

Molecular hydrogen is proposed to selectively scavenge reactive oxygen species and suppress excessive pro-inflammatory cytokines, thereby attenuating the cytokine storm central to COVID-19 pathophysiology.

Bibliographic

Authors
Li Y, Wang Z, Lian N, Wang Y, Zheng W, Xie K
Journal
Front Med (Lausanne)
Year
2021
PMID
34746162
DOI
10.3389/fmed.2021.671215
PMC
PMC8569706

Tags

Disease:COVID-19 (25) Delivery:inhalation delivery (196) Mechanism:hydroxyl radical scavenging (352) immune modulation (180) anti-inflammatory (743) oxidative stress (899) reactive oxygen species (774)

Delivery context

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

→ Evidence by delivery route

Safety notes

In air, molecular hydrogen is reported to be combustible across approximately **4% (LFL, lower flammability limit) to 75% (UFL, upper flammability limit)**. Among high-concentration hydrogen inhalers, 66% output sits inside this range, and even pure-hydrogen (100%) output forms a 4–75% concentration-gradient layer at the device–air boundary (the UFL 75% paradox). Engineering principle would therefore call for operation below LFL (the classical 4%); that figure, however, was measured under closed, pre-mixed, static conditions. For the open, dynamic inhalation environment, the empirical value reported in the literature is **10%**, which is the figure referenced in practice as the operating ceiling. The 66% / 100% output devices are recorded in the Japanese Consumer Affairs Agency accident-information database, and from these considerations are not recommended.

See also:

Other papers on the same disease / condition