Hydrogen Gas Inhalation Safety Tested in Acute Stroke Patients
A basic study on molecular hydrogen (H2) inhalation in acute cerebral ischemia patients for safety check with physiological parameters and measurement of blood H2 level
Research hubs: Brain & Nervous System · Cardiovascular System
- Evidence type
- Case report or series · Human study
- Authors
- Hirohisa Ono, Yoji Nishijima, Naoto Adachi, Masaki Sakamoto, Yohei Kudo, Kumi Kaneko, Atsunori Nakao, Takashi Imaoka
- Journal
- Medical Gas Research
- Year
- 2012
- PMID
- 22916706
- Study Type
- Human
- Participants
- 13
- Delivery
- Gas
- Dose
- 3-4% H2 gas inhalation for 30 minutes
- H₂ concentration
- 3-4% H2 gas
- Duration
- 1 day or less
- Conflicts of interest
- None declared
- Outcome
- Positive
- Peer Reviewed
- Yes
- Cited by
- 111 (OpenAlex, as of November 2026)
- Country
- Japan
TL;DR
Inhaling hydrogen gas appears to be a safe treatment that reaches effective levels in the blood for patients with brain ischemia, similar to successful animal studies, but the method of delivery needs to be more consistent.
Key Finding
Inhaling 3-4% hydrogen gas for 30 minutes safely delivered therapeutically relevant hydrogen levels to the blood in acute stroke patients without adverse effects on vital signs.
Summary
Researchers tested whether inhaling hydrogen gas (a colorless, odorless gas) is safe for stroke patients and whether it successfully delivers hydrogen into the bloodstream. They measured hydrogen levels in the blood of 13 patients before, during, and after breathing 3-4% hydrogen gas for 30 minutes, while monitoring heart rate, blood pressure, and other vital signs. The study found that hydrogen reached therapeutic levels in the blood (matching levels shown to be beneficial in animal studies) without causing any adverse effects on vital signs, though the amount of hydrogen absorbed varied between patients.
Practical Takeaway
This early-stage human safety study suggests hydrogen inhalation may be a feasible delivery method for stroke patients, but it is a very small study (13 patients) focused only on safety and blood hydrogen levels—not on whether hydrogen actually improves stroke outcomes. The researchers noted that standardizing the inhalation technique is needed to ensure consistent hydrogen delivery between patients. More research is required before any health benefits can be claimed.
Abstract (excerpt)
Background: In animal experiments, use of molecular hydrogen ( H2) has been regarded as quite safe and effective, showing benefits in multiple pathological conditions such as ischemia-reperfusion injury of the brain, heart, kidney and transplanted tissues, traumatic and surgical injury of the brain…