Hydrogen in Medicine: A Short History of H2 as a Medical Gas
"Hydrogen in medicine" usually means something narrower than it sounds: using hydrogen gas (H₂) itself, by inhalation or dissolved in water, as a possible antioxidant and anti-inflammatory agent, rather than hydrogen's familiar role as an industrial fuel or chemical reagent. The idea is older than most people expect. Isolated reports of handling hydrogen gas in and around the body go back centuries, the first deliberate attempt to use it as a cancer treatment dates to 1975, and the paper most researchers now point to as the field's real starting point was published in 2007. Everything that has followed in human research remains small, early-stage and mostly uncontrolled.
Before the detailed timeline, a few things are worth holding onto as you read:
- Hydrogen gas was documented as early as 1520, but for roughly 450 years afterward it was handled as an inert or diagnostic gas, not studied as a treatment in its own right.
- The first deliberate attempt to use hydrogen as a therapy was a 1975 hyperbaric study in animals with cancer, which stalled mainly because the equipment it required never became practical for routine use.
- A 2007 paper proposing hydrogen as a selective antioxidant, tested in cell culture and then in a rat stroke model, is the study most later hydrogen research cites as its starting point.
- Human studies published since 2007 are still few and small; a 2013 survey of the field found only one actively registered clinical trial of molecular hydrogen as a therapy anywhere.
- None of the research below tested a specific consumer device, so a home hydrogen inhaler is accurately described by its own measured specifications, not by any outcome in this history.
Where the idea of "hydrogen medicine" actually starts
If you came across the phrase "hydrogen medicine" next to a water bottle or an inhalation machine, it is reasonable to wonder whether this is a recent marketing idea or something with real research behind it. It is both newer and older than either guess: the gas itself has been known for five centuries, but treating it as a therapy you breathe or drink is recent and still developing. This article follows the gas-and-inhalation line of that history specifically, from early physiological curiosity through a single hyperbaric cancer experiment to the 2007 paper that reopened the question, and on to the small human studies published since. A related piece on this site covers the parallel story of hydrogen-infused drinking water and its popularization in Japan; the two strands share a chemical, not a timeline, so they are told separately.
A quick reference timeline
The table below lists the landmark dates in this history, what kind of evidence each one represents, and the source so you can check the original description yourself.
| Year | What happened | Type of evidence | Source |
|---|---|---|---|
| 1520 | Paracelsus is credited with the first documented production of hydrogen gas. | Historical account | Dixon et al., 2013 |
| 1783 | Lavoisier names the gas "hydrogène," the same year Jacques Charles flies the first hydrogen balloon. | Historical account | Dixon et al., 2013 |
| 1888 | A surgical report describes insufflating hydrogen gas into body cavities to locate visceral injuries. | Historical case report | Dixon et al., 2013 |
| 1975 | Dole, Wilson and Fife propose hyperbaric hydrogen as a cancer treatment, reasoning it might scavenge hydroxyl radicals. | Animal study | Dixon et al., 2013 |
| 1994 | Kayar and colleagues find mammalian tissue does not metabolize hydrogen even under pressure, supporting its use as a diving gas. | Laboratory/physiology | Dixon et al., 2013 |
| 2001 | Gharib and colleagues report hyperbaric hydrogen reduces parasite-induced liver inflammation in mice. | Animal study | Huang, 2016 |
| 2007 | Ohsawa and colleagues report normobaric, low-concentration hydrogen protects against oxidative injury in cell culture and a rat stroke model. | Cell and animal study | Huang, 2016 |
| 2013 | A field survey finds only one molecular-hydrogen therapy trial registered anywhere, for a sports-related injury. | Field review | Dixon et al., 2013 |
| 2020 | A pilot gives inhaled hydrogen to five comatose patients just resuscitated from cardiac arrest, with no control group. | Human pilot, n=5 | Tamura et al., 2020 |
Hydrogen as a tool, long before it was a treatment
For most of its documented history, hydrogen was something researchers and physicians handled rather than prescribed. Paracelsus's production of a flammable gas by dissolving a metal in acid, in 1520, is usually cited as the earliest documented hydrogen. Lavoisier named the gas in 1783, the same year Jacques Charles used it to fly the first hydrogen balloon; both milestones belong to chemistry and aviation, not therapy. The closest either era came to a medical use was an 1888 surgical report describing hydrogen insufflated into body cavities so surgeons could locate visceral injuries before deciding whether exploratory surgery was needed.
A diagnostic tool, not yet a therapy
That 1888 use is easy to mistake for an early therapy, but the hydrogen was not treating anything; it was a marker gas that let a surgeon find a problem so a separate procedure could address it. For the better part of a century afterward, hydrogen kept this supporting role as an inert or detectable gas used for measurement, propulsion or industrial chemistry, with no serious proposal that breathing or absorbing it could itself change the course of a disease.
1975: the first deliberate attempt to use hydrogen itself as a treatment
That changed, at least as a proposal, in 1975, when Dole, Wilson and Fife suggested that hydrogen gas under high pressure might work as a cancer treatment, reasoning that it could scavenge hydroxyl radicals, a particularly reactive and damaging oxidative byproduct generated in living tissue. It was the first time the gas itself, rather than a measurement tool or an inert filler, was proposed as the active agent.
What the 1975 study actually tested
How well that hypothesis held up depends on which account you read. A later, widely cited review describes two weeks of hyperbaric exposure to 97.5% hydrogen as producing marked regression of skin tumors in the treated animals (source: Huang, 2016). The original 1975 report is terser and harder to verify independently, so it is fairer to treat this description as the reviewing authors' characterization rather than an independently reproduced, settled finding.
Why a hyperbaric chamber never became standard care
Whatever the precise outcome, the method itself explains why the approach went no further: producing an effect required sealing an animal, and eventually a patient, inside a pressurized hydrogen chamber for an extended period. That kind of equipment is expensive, specialized and carries its own handling risks, which limited any quick follow-up and kept hyperbaric hydrogen from becoming a practical treatment.
Hydrogen's other life: a breathing gas, not a drug
While the cancer hypothesis sat largely dormant, hydrogen had an active career in an unrelated field: deep-sea diving. Divers have breathed Hydreliox, a mixture of 49% hydrogen, 50% helium and 1% oxygen, specifically to prevent decompression sickness during very deep dives, with no therapeutic intent (source: Huang, 2016). The 1994 finding that mammalian tissue does not metabolize hydrogen gas even under pressure reinforced treating it as an inert breathing gas rather than a substance the body processes. Much of what is known today about safely inhaling high concentrations of hydrogen traces back to this diving work rather than to any medical trial (source: Ohta, 2011), which is part of why later hydrogen-medicine researchers could set concentration limits before testing the gas in people.
2007: the paper that restarted the field
The paper that changed the field's trajectory came from Ohsawa and colleagues in 2007. They tested a normobaric, 2% concentration of hydrogen gas, deliberately kept below the roughly 4% flammability threshold, first in cell culture and then in a rat model of focal brain ischemia-reperfusion, the injury pattern that follows a stroke and the restoration of blood flow afterward. Their central claim was mechanistic: hydrogen appeared to selectively neutralize the hydroxyl radical, one of the more destructive reactive oxygen species, while largely sparing other reactive oxygen species the body uses for ordinary cell signaling (source: Huang, 2016). For the fuller explanation of that antioxidant mechanism on its own, our explainer on what molecular hydrogen actually is covers it in more depth than a history piece can.
What the 2007 study actually showed, and what it didn't
Taken at face value, the result showed that a specific, low, non-flammable concentration of hydrogen gas reduced oxidative damage in cultured cells and in a rat stroke model, through a plausible and testable mechanism. It was not the first protective effect reported in an animal model; a smaller 2001 study by Gharib and colleagues had already found hyperbaric hydrogen reducing parasite-driven liver inflammation in mice. What set 2007 apart was the combination of a clear mechanism, a practical, non-hyperbaric delivery method, and a stroke model other researchers immediately recognized as clinically relevant. It is just as important to be precise about what the paper did not establish: it was a cell-culture and rat study, it said nothing directly about a human stroke patient, and it tested a laboratory gas protocol, not any consumer product. Every later claim about hydrogen in people builds on this starting point, not on a confirmation that existed in humans at the time.
From rats to a handful of patients: how slowly human evidence has followed
Human research has moved far more slowly than the laboratory interest that followed 2007. One of the clearer attempts to test inhaled hydrogen in people gave it to five comatose adults just resuscitated from out-of-hospital cardiac arrest, alongside the standard temperature-management care those patients already receive, with no comparison group to show what would have happened otherwise. Oxidative-stress markers fell in the four patients whose arrest had a cardiac cause, but inflammatory markers barely moved, and the researchers themselves described the effect as "indefinite because of methodological weaknesses," calling for larger, controlled trials (source: Tamura et al., 2020). A 2013 survey of the field underlines how early-stage this still is: at that point, only a single clinical trial of molecular hydrogen as a therapy was actively registered anywhere, studying a sports-related injury (source: Dixon et al., 2013).
Inhalation is also only one route researchers have studied; the broader literature includes drinking hydrogen-dissolved water, hydrogen baths, intravenous hydrogen-dissolved saline, hydrogen-saline eye drops, and attempts to raise hydrogen production by gut bacteria (source: Ohta, 2011). If you are weighing inhalation against the drinking-water approach most people encounter first, our comparison of hydrogen inhalation and drinking hydrogen water lays out what each route has actually been studied for.
What this history does, and doesn't, say about the inhaler on your counter
None of the studies traced above tested a specific consumer inhalation machine; they tested a gas, at a stated concentration, in a laboratory or in a very small group of hospitalized patients. A device like the Hydrion Zenith, whose product page states an output range of 300 to 1,800 ml/min and 99.99% hydrogen purity across both pure-H₂ and mixed H₂/O₂ modes, or the Hydrion Titan, is built and sold on specifications like these, not on having reproduced the outcome of any study in this timeline. Reading the research history helps you understand where the idea came from and how thin the human evidence base still is; it is not a substitute for checking what a particular machine's own specification sheet states, and it is not a basis for expecting any specific health outcome from using one. If you are new to inhaling hydrogen gas day to day, our beginner's guide to hydrogen inhalation therapy covers the practical side, and our buyer's guide to choosing a hydrogen inhalation machine walks through how to compare models like these on their own terms.