Hyperbaric oxygen, read through the evidence
A calm, organised place to explore what the research actually says about hyperbaric oxygen therapy — from established indications to contested frontiers — with every claim graded by evidence strength and traced to a real source.
Nine rooms, one honest thread
Each section is self-contained and cross-linked. A shared evidence-strength system runs through all of them, so the difference between an approved indication and a newspaper claim is always visible.
The Science
How pressure and oxygen act on tissue, vessels and cells — grounded in referenced mechanism work.
Enter →Reading the Evidence
The grading framework used across this site, adapted from the ECHM consensus method.
Enter →Indications & Standards
The UHMS approved list and the European (ECHM) approach to recognised uses.
Enter →Neurology & Brain
Stroke, brain injury, post-COVID and cognition — trial by trial, labelled by design.
Enter →Emerging & Contested
Recovery, longevity, autism, addiction, performance — the frontier, honestly graded.
Enter →Safety & Operations
Contraindications, side-effects and the real fire risk of oxygen-enriched chambers.
Enter →Not all "evidence" is equal
A randomised controlled trial and a newspaper feature can make the same claim — that oxygen heals the brain — but they carry very different weight. This library keeps them apart on purpose. Approved indications sit in their own room; experimental uses are marked; and where a source is a case report or press coverage, it says so plainly.
What hyperbaric oxygen is proposed to do
HBOT means breathing near-100% oxygen inside a chamber pressurised above sea level — clinically, usually about 2.0–2.8 atmospheres absolute (ATA), with maximum oxygen partial pressure kept at or below 3 ATA to limit toxicity. Under pressure, far more oxygen dissolves directly into blood plasma and reaches tissue. The mechanisms below are drawn from referenced physiology work, including a detailed review of HBOT's cellular actions in wound and combat medicine.
Plasma-dissolved oxygen
Pressurisation forces oxygen into plasma independent of red blood cells, raising tissue oxygen many times above normal — the basis for treating poorly-perfused or ischaemic tissue.
Angiogenesis & healing signals
HBOT is reported to hasten new-vessel growth and to modulate growth factors integral to wound healing (VEGF, PDGF, FGF, TGF-β), supporting its established wound-healing indications.
The "HBO paradox"
Many processes normally triggered by low oxygen (angiogenesis, collagen synthesis) are paradoxically also up-regulated by intermittent hyperoxia — a proposed basis for regenerative effects without the tissue damage of true hypoxia.
Anti-inflammatory & antimicrobial
HBOT is reported to reduce reperfusion injury by inhibiting leukocyte (β-2 integrin) adhesion, to restore bactericidal activity of immune cells, and to reduce tissue oedema.
The relevance of hyperbaric oxygen to combat medicine
How this library grades what it shows
Hyperbaric medicine's own professional bodies grade evidence formally. The European Committee for Hyperbaric Medicine (ECHM), at its 7th Consensus Conference (Lille, 2004), set out a scale that is a useful lens for everything in this library: it separates the level of evidence from the strength of a recommendation. The tags used throughout these pages map onto that thinking.
Level 1 — Strong
At least two concordant, large, double-blind, randomised controlled studies with no or only weak methodological bias.
Level 2 — Moderate
Double-blind randomised studies, but with methodological bias, small samples, or only a single study.
Level 3 — Weak
Based only on expert consensus or uncontrolled studies (historic control group, cohort study).
Level 4 — None
Case report only, or methodological/interpretation bias precluding any conclusion.
- Type 1 — Strongly recommended. Implementation considered of critical importance to patient outcome.
- Type 2 — Recommended. Considered to positively affect outcome or quality of practice.
- Type 3 — Optional. Considered a reasonable option.
Recommendations are further tagged Level A / B / C according to whether they rest on level 1, 2 or 3 evidence.
Recognised, approved indication (UHMS / ECHM).
Randomised controlled trial — but read sample size and replication.
Systematic or narrative review synthesising many studies.
Early or mixed evidence; promising but not settled.
Case report or press coverage — a story, not proof.
Where the evidence is strongest
Two professional bodies anchor the recognised uses of HBOT: the Undersea and Hyperbaric Medical Society (UHMS) in the United States, and the European Committee for Hyperbaric Medicine (ECHM). Their approved lists differ from the experimental uses elsewhere in this library — these are the indications the field itself recognises.
- Air or gas embolism
- Carbon monoxide poisoning (incl. cyanide complication)
- Clostridial myositis and myonecrosis (gas gangrene)
- Crush injury, compartment syndrome & acute traumatic ischaemias
- Decompression sickness
- Arterial insufficiencies: central retinal artery occlusion
- Arterial insufficiencies: selected problem wounds
- Severe anaemia
- Intracranial abscess
- Necrotising soft-tissue infections
- Refractory osteomyelitis
- Delayed radiation injury (soft-tissue & bony necrosis)
- Compromised grafts and flaps
- Acute thermal burn injury
- Idiopathic sudden sensorineural hearing loss
- Avascular necrosis (aseptic osteonecrosis)
ECHM & the Code of Good Practice
The ECHM consensus conferences define, for Europe, which indications are accepted and how hyperbaric centres should operate. A companion European Code of Good Practice for hyperbaric oxygen therapy sets operational and safety standards. Both are represented in your reference library.
Two bodies, similar core
UHMS and ECHM lists are not identical and are revised periodically, but they converge on the same well-evidenced core: decompression illness, gas embolism, carbon monoxide poisoning, serious infections, compromised wounds, and radiation injury. Always check each body's current edition.
The brain evidence, trial by trial
One of the most active — and most debated — frontiers for HBOT. The studies below are real and peer-reviewed; the tags mark study design. Most brain trials are relatively small and several come from the same research groups, so independent replication matters. None of these uses is currently an approved indication.
Hyperbaric oxygen induces late neuroplasticity in post-stroke patients
HBOT can improve post-concussion syndrome years after mild traumatic brain injury
Case report: treatment of mild traumatic brain injury with hyperbaric oxygen
HBOT improves neurocognitive function and symptoms of post-COVID condition
Cognitive enhancement of healthy older adults using hyperbaric oxygen
HBOT in children with post-concussion syndrome improves cognitive and behavioural function
Hyperbaric oxygen therapy as a neuromodulatory technique: a review of recent evidence
The frontier — read the tags carefully
These are the uses you'll most often see marketed. The evidence here is uneven: some is early clinical research, some is a single small study, and some is press coverage making claims well ahead of the data. Nothing on this page is an approved indication. The tags are your guide to how much weight each item can bear.
Effects of HBOT on exercise-induced muscle injury and soreness
HBOT increases telomere length and decreases immunosenescence in isolated blood cells
HBOT treated as a performance enhancer in horse racing
Study of the effect of hyperbaric oxygen therapy in Egyptian autistic children
"The big O2: oxygen is proving a revolutionary therapy for addicts"
Search the evidence directly
Every link below opens a genuine, authoritative database. Where possible the search is pre-built so you land on hyperbaric-oxygen results — always the current version, straight from the source.
PubMed
The U.S. National Library of Medicine index — over 35 million biomedical citations.
All HBOT studies ↗Cochrane Library
The gold standard for systematic reviews — the most rigorous synthesis of clinical evidence.
HBOT reviews ↗ClinicalTrials.gov
The registry of publicly and privately funded studies worldwide — see what is being tested now.
HBOT trials ↗UHMS
The Undersea and Hyperbaric Medical Society — sets US approved indications and standards.
Visit UHMS ↗Europe PMC
Free full-text access to much of the biomedical literature indexed in PubMed.
Search full text ↗WHO ICTRP
The WHO's international registry, aggregating trial registers from around the world.
Search ICTRP ↗Risks, contraindications and chamber safety
HBOT is generally well tolerated when delivered by trained staff in an accredited facility — but it is a medical intervention with real contraindications, physiological side-effects, and a genuine fire hazard from the oxygen-enriched environment. This is general educational information, not a substitute for evaluation by a physician.
- Ear and sinus barotrauma from pressure changes (most common)
- Temporary short-sightedness (myopia) that usually resolves after treatment ends
- Claustrophobia or anxiety inside the chamber
- Rarely, oxygen toxicity affecting the lungs or, affecting the CNS, seizures
- Fatigue after sessions
- Untreated pneumothorax (collapsed lung) — a key absolute contraindication
- Certain recent ear or chest surgery
- Some medications and lung conditions require specialist review
- Fever, certain implanted devices, and pregnancy may require caution
Illustrative, not exhaustive — eligibility must be assessed individually by a qualified clinician.
Flammability rises with oxygen
An oxygen-enriched atmosphere raises the flammability of materials and lowers the energy needed to ignite them. Laboratory work shows oxygen-concentration flammability thresholds vary systematically with total pressure — which is why chamber fire-prevention (eliminating ignition sources, limiting combustibles, controlling static and clothing) is treated so seriously.
Even "safe" metals need care
A commentary in aerospace/hyperbaric medicine notes that a freshly-broken titanium surface (e.g. snapped titanium eyeglass frames) in a near-100% oxygen environment — as in a monoplace chamber or oxygen hood — can, in principle, ignite. The authors recommend keeping breakable titanium items out of pure-oxygen chamber environments.
Monoplace vs multiplace
In a monoplace chamber (or with an oxygen hood) the patient is surrounded by close to 100% oxygen; in a multiplace chamber the room is pressurised with air and the patient breathes oxygen by mask or hood. Treatment is typically at about 2.0–2.8 ATA, with oxygen partial pressure capped near 3 ATA to limit toxicity. Operational standards for both types are set out in UHMS and European (ECHM) guidance in your reference library.
Beware the cure-all pitch
For its approved indications the evidence is solid; for many popular "wellness" uses it is early or contradictory. Ask a provider what accreditation they hold, what pressure and protocol they use, and what published evidence supports the specific use you're considering.
Sources cited in this library
Published papers link to their original record. Documents from your own reference library (standards, guidelines, grey literature and press) are cited in full and marked as such rather than linked to an invented URL.
- Efrati S, Fishlev G, Bechor Y, et al. Hyperbaric oxygen induces late neuroplasticity in post-stroke patients — randomized, prospective trial. PLOS ONE. 2013;8(1):e53716. DOI ↗
- Boussi-Gross R, Golan H, Fishlev G, et al. HBOT can improve post-concussion syndrome years after mild TBI — randomized prospective trial. PLOS ONE. 2013;8(11):e79995. Reg. NCT00715052. DOI ↗
- Wright JK, Zant E, Groom K, Schlegel RE, Gilliland K. Case report: treatment of mild traumatic brain injury with hyperbaric oxygen. Undersea Hyperb Med. 2009;36(6):391. PubMed ↗
- Zilberman-Itskovich S, Catalogna M, Sasson E, et al. HBOT improves neurocognitive functions and symptoms of post-COVID condition: RCT. Scientific Reports. 2022;12:11252. DOI ↗
- Hadanny A, Daniel-Kotovsky M, Suzin G, et al. Cognitive enhancement of healthy older adults using hyperbaric oxygen: RCT. Aging. 2020;12(13):13740–13761. DOI ↗
- Hadanny A, et al. HBOT in children with post-concussion syndrome improves cognitive and behavioural function: RCT. Scientific Reports. 2022. Nature ↗
- Hachmo Y, Hadanny A, Abu Hamed R, et al. HBOT increases telomere length and decreases immunosenescence in isolated blood cells: prospective trial. Aging. 2020;12(22). DOI ↗
- El-baz F, Elhossiny RM, Abdel Azeem Y, Girgis M. Study the effect of hyperbaric oxygen therapy in Egyptian autistic children: a clinical trial. Egypt J Med Hum Genet. 2014;15:155–162. DOI ↗
- Frontiers in Neurology. HBOT as a neuromodulatory technique: a review of recent evidence. 2024;15:1450134. Frontiers ↗
- Effects of HBOT on exercise-induced muscle injury and soreness: systematic review and meta-analysis. 2025. PubMed ↗
- Bennett M, et al. Hyperbaric oxygen therapy for stroke: a systematic review of the evidence. PubMed ↗
- Undersea and Hyperbaric Medical Society. Approved Indications for Hyperbaric Oxygen Therapy. uhms.org ↗
- European Committee for Hyperbaric Medicine. 7th European Consensus Conference on Hyperbaric Medicine, Lille, 3–4 December 2004 (evidence-grading framework; jury president Prof. F. Wattel). Reference library.
- European Code of Good Practice for Hyperbaric Oxygen Therapy (May 2004). Reference library.
- Wright JK. The relevance of hyperbaric oxygen to combat medicine. RTO HFM Symposium, Toronto, Oct 2000; RTO MP-062. Reference library.
- Hink J, Jansen E. Titanium in a hyperbaric oxygen environment may pose a fire risk. Aviat Space Environ Med. 2003;74(12):1301–1302. Reference library.
- Hirsch D, Williams J, Beeson H. Pressure effects on oxygen concentration flammability thresholds of materials for aerospace applications. J Testing & Evaluation. 2006. Reference library.
- UHMS Guidelines for monoplace hyperbaric chamber operations; Fundamentals of Hyperbaric Medicine. Reference library.
- Christie J. The big O2: oxygen is proving a revolutionary therapy for addicts. Scotland on Sunday, 20 July 2010. Press feature — reference library.
- Yusko D. HBOT for performance enhancement (New York racehorse racing rule). News item, 29 July 2009. Reference library.