An often-cited estimate for the number of cells in a standard adult body. The exact number varies by body size and how cells are counted.
The research, made understandable
What changes
when oxygen
can reach further?
Start with the biology. Then explore the evidence, the limits and the questions that still remain.
Start with the big idea ↓The hidden scale inside you
Healing happens in a world
too small to see.
Your body is not one object. It is a living network of cells, capillaries, electrical signals and continuous energy use. HBOT acts within this microscopic environment by changing one important condition: oxygen availability.
A vast signalling network supported by a similar number of non-neuronal brain cells.
The approximate rate at which an adult body uses energy at rest—continuously, day and night.
Cells continually regenerate ATP to power ion balance, movement, signalling, maintenance and repair.
O2
This is the environment in which HBOT works.
HBOT does not make the body heal by magic. Under increased pressure, more oxygen dissolves into blood plasma. That can raise oxygen availability in viable, perfused tissue—the microscopic setting in which cells make energy, communicate and carry out repair.
HBOT cannot revive dead tissue or replace a blocked blood supply. Whether it can help depends on the condition, tissue viability, protocol and person.A long-established international field
From an experimental pressure chamber in 1662 to modern medical HBOT.
The commonly cited history of medical hyperbaric treatment begins in 1662, when British physician Nathaniel Henshaw described a chamber called the Domicilium. It used compressed air—not oxygen—and was very different from a modern hyperbaric oxygen chamber. Modern HBOT developed later as pressure science, oxygen physiology, diving medicine and clinical practice advanced.
Who uses hyperbaric medicine?
Used across healthcare, emergency response and specialist practice.
For selected acute conditions, complex wounds, radiation injury and difficult infections.
As an adjunct to surgery, antibiotics, vascular assessment and advanced wound management.
For decompression sickness, arterial gas embolism and selected carbon-monoxide poisonings.
For recognised indications and carefully screened emerging applications where the evidence is still developing.
What conditions are treated?
Evidence is established for some conditions and still developing for others.
International hyperbaric medicine organisations recognise uses including decompression sickness, air or gas embolism, carbon-monoxide poisoning, selected non-healing diabetic wounds, delayed radiation tissue injury, refractory osteomyelitis, compromised grafts and flaps, necrotising soft-tissue infection, severe anaemia in selected circumstances and sudden sensorineural hearing loss.
HBOT is also being researched for brain injury, persistent post-concussion symptoms, long COVID, fibromyalgia, healthy ageing and other conditions. Research interest does not mean that benefit has been proven for every person or every diagnosis.
Every day, HBOT is used around the world.
Although no single international register exists, available patient estimates suggest that well over 100,000 hyperbaric treatment sessions may be delivered globally each day across hospitals, wound-care services, specialist clinics and emergency facilities. Each session forms part of a medical field with centuries of history and an expanding international research base.
The governing idea
Support the environment in which recovery happens.
Oxygen, light and cellular redox chemistry act through different pathways. They are not interchangeable, and combining them does not guarantee a stronger result.
Our approach begins with the person: their history, medicines, objectives and measurable baseline. The protocol follows the assessment — never the other way around.
01
Pressure changes what oxygen can reach.
Hyperbaric oxygen therapy
HBOT combines increased atmospheric pressure with prescribed oxygen exposure. Under pressure, more oxygen dissolves into plasma, supporting oxygen delivery beyond what red blood cells carry alone.
Protocols are selected around the person, objective and risk profile — not a one-size-fits-all session.
02
Light becomes a biological signal.
Red-light therapy
Photobiomodulation uses measured red and near-infrared wavelengths. Cells absorb the light and may alter mitochondrial signalling, blood flow and inflammatory responses. Wavelength, dose and distance all matter.
More light is not automatically better. Treatment is delivered within a defined dose window.
03
A molecule that demands respect.
Methylene blue
Methylene blue is a prescription medicine with redox and mitochondrial effects under investigation. It is not a general wellness supplement and is not suitable for everyone.
Clinical screening is essential because of medicine interactions, G6PD deficiency and other contraindications.
Understanding HBOT
What if your body can repair—but not the conditions?
Every repair process needs energy, and making that energy requires oxygen. After injury, inflammation, infection, radiation damage or poor circulation, oxygen may not reach living tissue as effectively.
The tissue may need more oxygen to repair itself at the very time oxygen delivery is reduced.
Why pressure changes the picture
More oxygen can travel in the liquid part of blood.
Normally, most oxygen rides on haemoglobin inside red blood cells. In a hyperbaric chamber, you breathe high-concentration oxygen while the surrounding pressure is safely increased. That pressure allows much more oxygen to dissolve directly into plasma—the liquid around your blood cells.
This creates a stronger oxygen gradient, which may help oxygen move further from working capillaries into nearby living tissue.
NormallyMost oxygen rides on red cells
pressure + oxygen ↓
During HBOTExtra oxygen dissolves in plasma
red blood cell dissolved oxygen
What it can—and cannot—do
HBOT supports living tissue. It does not revive dead tissue.
- Mitochondrial energy production
- Collagen formation
- Immune defence
- Wound-repair processes
- Oxygen-threatened but viable tissue
- Blood flow through a completely blocked artery
- Removal of dead tissue
- Surgery when surgery is needed
- Antibiotics for a bacterial infection
- Appropriate specialist care
Before
Swelling increases the distance
HBOT →
During HBOT
Less fluid + more dissolved oxygen
The oxygen–swelling paradox
Less swelling. Greater oxygen availability.
High oxygen levels can temporarily constrict certain blood vessels, which may reduce fluid leakage and swelling. Normally, less blood flow would mean less oxygen.
During HBOT, however, plasma carries substantially more dissolved oxygen. Tissue oxygen can therefore rise even while some vessels constrict. As swelling falls, oxygen may also have a shorter distance to travel from capillaries to cells.
+1,430%measured skin tissue oxygen pressure in seven healthy volunteers during the study’s HBOT exposure, despite mild vasoconstriction.Read the human study ↗One session versus a course
One treatment delivers oxygen. A course may signal adaptation.
The oxygen increase during a session is temporary. With properly selected repeated exposures, research suggests HBOT may also influence inflammatory signalling, antioxidant defences, nitric-oxide activity, vascular growth factors and the development of small blood vessels in selected tissue.
One session
Temporary rise in tissue oxygen
Selected course
2× after one exposure8× over 20 treatmentsCirculating CD34-positive cells in a human study using 2.0 ATA oxygen for two hours. These cells support repair biology; they do not guarantee healing.Read the study ↗Repeated controlled signals → possible adaptation
+
An addition, not a replacement
HBOT does not replace good medical care.
HBOT does not perform the repair for your body. Its potential value is helping create a better-oxygenated biological environment in which repair may become more possible.
Whether it is appropriate depends on the condition, viable tissue, blood supply, pressure, oxygen dose and number of sessions. Evidence is strong for some recognised conditions and still developing for others.
Is HBOT appropriate for you?
The next step is not to assume.
It is to assess.
The useful question is whether impaired oxygen delivery may be part of your problem—and whether HBOT is a reasonable addition to your existing care.
Book an assessment →HBOT & the injured brain
How HBOT may help an injured brain.
Your brain is small but energy-hungry. Although it is only about 2% of body weight, it uses roughly 20% of the body’s oxygen at rest. That oxygen helps brain cells make ATP—the energy used to communicate, maintain electrical balance and support repair.
2%of body weight
but uses
20%of resting oxygen
After concussion or TBI
The brain can face an “energy crisis”.
A concussion is a mild traumatic brain injury. The brain may be shaken, stretched or twisted inside the skull. The original event can last seconds, yet start a much longer chain of problems.
Demand ↑More energy is neededto reset cell membranes, ion pumps and chemical signalling
ATPenergy gap
Supply ↓Energy may be harder to makewhen inflammation and disturbed blood flow limit delivery
Brain tissue is shaken, stretched or twisted.
Membranes, tiny vessels, nerve connections and signalling can be affected.
Sodium, potassium and calcium shift; mitochondria work harder.
Headache, poor concentration, dizziness, sleep problems, light sensitivity, anxiety or fatigue.
Most people recover with appropriate rest followed by a gradual return to activity. Persistent symptoms deserve medical assessment and a structured rehabilitation plan.
What happens during a stroke?
Some tissue is lost quickly. Nearby tissue may still be alive.
An ischaemic stroke happens when a clot blocks blood flow. A haemorrhagic stroke happens when a vessel ruptures and bleeding damages surrounding brain.
In a severe ischaemic stroke, tissue at the centre may die quickly. Around it can be injured tissue receiving too little oxygen that may still be viable. This region is called the penumbra.
working tissue
penumbra
at risk, may still be alive
at risk, may still be alive
core
severely damaged
severely damaged
HBOT cannot revive dead tissue or reopen a blocked artery. Its proposed target is viable, perfused tissue—not the dead core.
!
Suspected stroke? Call 111 immediately.
Face drooping, arm weakness or speech difficulty means emergency care now. HBOT must never delay an ambulance, brain imaging, clot-dissolving medicine or thrombectomy.
How could HBOT help?
More dissolved oxygen may support viable—but stressed—brain tissue.
Pressure allows extra oxygen to dissolve in plasma, creating a stronger gradient from blood into living, perfused tissue. These are proposed support pathways, not promises of brain regeneration.
Cellular energy
When oxygen delivery is limiting, mitochondria may struggle to make ATP. More available oxygen may support membranes, ion pumps and communication.
Inflammation control
Controlled exposures may influence inflammatory signalling and antioxidant defences—helping the body move from prolonged injury response towards repair.
Swelling + oxygen
Temporary vessel constriction may reduce leakage and swelling while oxygen-rich plasma helps tissue oxygen remain elevated.
Neuroplasticity
Repeated sessions may influence growth factors, vascular signalling and metabolism—conditions that could support rehabilitation and new connections.
Repair signalling
A course may stimulate signals linked with new small blood vessels and certain progenitor cells. This does not guarantee tissue regrowth.
Brain perfusion · what the scans show
More oxygen can reach active brain networks—not simply “flood the brain”.
Perfusion means blood delivery through tissue. During HBOT, pressure greatly increases the oxygen carried in plasma. Across a course of treatment, some human studies have also measured changes in regional cerebral blood flow.
The important word is regional: imaging has shown changes in selected networks rather than a uniform increase across every part of every brain.
01Oxygen under pressuremore oxygen dissolves in plasma
→02Viable brain tissueoxygen follows blood flow and diffusion gradients
→03Mitochondrial ATPenergy for ion pumps, signalling and maintenance
→04Network functionpossible support for cognition, regulation and movement
Making the imaging easier to see
What a before-and-after brain scan can look like.
These original scan-style illustrations simplify patterns reported in the linked human studies. They are not copied patient scans, diagnostic images or a promise that every brain will change in this way.
Before course
Lower regional signal
course of HBOT→
After course
Higher signal in selected frontal, motor-planning and parietal areas
lower relative signalmoderatehigher relative signal
How to read it: the brighter areas do not mean the whole brain received uniformly more blood. They show where the imaging analysis detected a relative regional change.
Before course
Fewer or weaker measured connections
course of HBOT→
After course
Changed connectivity across selected regulation networks
How to read it: functional connectivity does not photograph thoughts. It measures whether activity in different regions changes together over time. A changed pattern may support a neuroplasticity interpretation when clinical measures improve alongside it.
Frontal and parietal networks
These regions help us focus, hold information in mind, change strategy, plan and process information. In a randomised trial of healthy older adults, increased blood flow in selected frontal, supplementary motor and parietal regions occurred alongside improvements in attention, processing speed and global cognition.
focusworking memoryplanningprocessing speed
Connected regulation networks
Mood is not located in one “mood centre”. It emerges from communication between frontal control regions, the limbic system, insula, cingulate and other networks. Improving oxygen availability may support the energy demands of viable cells in these systems, while HBOT trials in PTSD have reported symptom and connectivity changes.
That does not establish HBOT as a general treatment for depression or anxiety, or prove that extra perfusion caused a mood change.
Motor-planning networks
Supplementary motor and related frontal regions help initiate, organise and sequence movement. Better-supported viable tissue may contribute to coordination, reaction, rehabilitation and task performance—particularly when combined with appropriate neurological or physical rehabilitation.
movement planningreactioncoordinationtask control
2020 · randomised controlled trial · 63 healthy adults over 64Regional cerebral blood-flow changes accompanied gains in attention, processing speed and global cognition.Read the healthy-ageing study ↗2013 · randomised crossover trial · persistent post-concussion symptomsSPECT activity changes were reported in conjunction with improvements in cognitive function and quality of life.Read the post-concussion study ↗2024 · randomised sham-controlled trial · combat-associated PTSDSymptom improvement was accompanied by measurable changes in brain-network connectivity.Read the PTSD trial ↗
Positive randomised trials
Clinical trials have reported meaningful improvements.
These randomised controlled trials reported improvements following HBOT in people with persistent symptoms after mild traumatic brain injury or other non-stroke brain injury. Each study used a defined protocol and measured outcomes before and after treatment.
This is a focused selection of positive RCTs—not a claim that every trial has been positive or that every patient will respond. Results still depend on the injury, timing, treatment protocol and individual.
2025 · double-blind, sham-controlled RCT47 analysed · 40 sessions
HBOT produced a greater improvement than sham in the overall symptom score. Improvements were also reported in smell, anxiety, sleep difficulties and balance-related complaints.
Persistent symptoms after non-stroke brain injuryRead the trial ↗2020 · randomised crossover RCT50 completed primary testing · 40 sessionsCompared with a no-treatment period, HBOT was associated with improvements in post-concussion symptoms, memory, cognitive function, anxiety, depression, sleep and quality of life.
Persistent post-concussion symptoms after mild TBIRead the trial ↗2013 · prospective randomised crossover RCT56 participants · 40 sessions at 1.5 ATACognitive function and quality of life improved after HBOT, while no significant improvement occurred during the control period. SPECT imaging changes were reported alongside the cognitive improvements.
Persistent post-concussion symptoms 1–5 years after mild TBIRead the trial ↗2023 literature review · traumatic brain injury
Not every brain injury is the same—and neither is the evidence.
Hadanny, Maroon and Efrati reviewed human clinical research published from 1969 to April 2023. Their key move was to separate TBI by severity and by time since injury.
That matters because emergency treatment after a severe injury asks a different question from rehabilitation months or years after a concussion.
1969
4 research databasesCochrane Library · PubMed · Google Scholar · Web of Science
April 202301 · Acute or subacuteHigh-level evidence
Moderate–severe TBI
9randomised controlled trials1meta-analysis2prospective studies
Mortality was significantly reduced in studies that measured it. Functional outcomes among survivors were mixed.
02 · ChronicLow–moderate evidence
Severe TBI
2uncontrolled prospective studies2cohort studies8case reports
The available studies suggested improvement, but the evidence was less certain because stronger controlled trials were limited.
03 · ChronicHigh-level evidence
Mild TBI + persistent symptoms
7randomised controlled trials6prospective studies
The review reported evidence of improvement in cognitive function, symptoms and quality of life in selected patients.
The review’s practical message
Selection should come before treatment.
For chronic post-concussion symptoms, the authors did not recommend treating everyone based on symptoms alone. They proposed identifying selected patients with evidence of metabolically dysfunctional but potentially viable brain regions.
Persistent symptomsafter appropriate recovery time
→Cognitive testingobjective baseline measures
→Functional imaginglook for metabolic dysfunction
→Selected patientindividual clinical decision
Why this review is useful
It brings acute and chronic TBI research into one framework, distinguishes mild from severe injury and makes patient selection central rather than assuming one protocol suits everyone.
How to read it carefully
This is a literature review—not a new RCT or meta-analysis. Included studies used different pressures, oxygen doses, timing and controls. Its recommendations are the authors’ clinical interpretation, not a universally adopted standard of care.
2021 narrative review · cognition & mechanisms
How might repeated oxygen exposures influence the brain?
Gottfried, Schottlender and Ashery brought together clinical, animal and laboratory research on HBOT, brain function and cognition.
The paper is best understood as a map of possible pathways. It explains how findings may connect; it does not test one group of patients in a new clinical trial.
Study typeNarrative review≠randomised controlled trial
01Repeated HBOTalternating high oxygen and return to normal oxygen
→02Cell signalsHIF-1α · Nrf2 · SIRT1 and other pathways
→03Support processesenergy · blood vessels · inflammation · cell protection
→04Possible outcomeschanges in blood flow, metabolism and cognitive performance
Mitochondria & ATP
The review describes mitochondria as a likely central target because they use oxygen to make ATP. Much of the detailed evidence about ATP, apoptosis and mitochondrial transfer came from animal or cell models.
Angiogenesis & perfusion
Repeated exposure may activate signals linked with new small blood vessels and improved cerebral blood flow. Human studies reviewed reported associations between perfusion changes and cognitive gains.
Inflammation, antioxidants & plasticity
The review links HBOT with antioxidant defences, inflammatory signalling and pathways involved in cell survival and neuroplasticity. The strength of evidence varies by pathway and study model.
What kind of evidence is inside?
Several evidence levels—different questions.
Human studiescognition, symptoms, blood flow and metabolismAnimal modelsbrain injury, Alzheimer-like disease and vascular dementiaCell researchmolecular pathways and proposed mechanisms
What the review supports
There are biologically plausible ways HBOT could influence brain energy, circulation, inflammation and plasticity, alongside encouraging clinical signals in selected populations.
What it does not prove
A narrative review cannot establish that HBOT prevents dementia, reverses neuron loss or improves cognition for everyone. Protocols and patient groups differed, and many mechanistic findings were preclinical.
PTSD · post-hoc analysis of RCT data
Could recovery continue after the chamber course ends?
Danan and colleagues reanalysed results from a randomised, sham-controlled trial involving male veterans with long-standing, treatment-resistant combat-related PTSD.
The question was unusual and important: was there a level of early improvement beyond which recovery appeared more likely to continue?
Study typePost-hoc threshold analysisusing data froma sham-controlled RCT
56male veterans completed the RCT
→60HBOT or sham sessions
→CAPS-5clinician-rated PTSD symptoms
→3 monthsfollow-up after treatment
The central finding
A 35% improvement marked a possible turning point.
Participants who had improved by at least 35% on the CAPS-5 scale at the end of treatment showed continued improvement at the three-month follow-up. Those below this data-derived threshold were more likely to lose some of their earlier gains.
This does not mean 35% is a universal biological switch. It is a pattern detected retrospectively in this particular dataset and needs prospective validation.
0%35%possible thresholdgreater improvement
Which symptoms carried the signal?
Intrusion showed the strongest relationship. Avoidance helped predict what happened next.
The strongest reported correlation between symptom-cluster change and total CAPS change at follow-up.
Change at treatment completion was the best predictor of subsequent improvement in the analysis.
The active protocol
A full, tightly defined medical course.
60 sessions5× per week2 ATA pressure90 min 100% oxygen5 min air break every 20 minutes
What this adds
The study suggests that the size of improvement at treatment completion—not the starting CAPS-5 score—may help identify who is more likely to sustain or extend gains after a full HBOT course.
How to read it carefully
This was a retrospective, data-driven analysis rather than a new prospectively designed threshold trial. The sample was small, all participants were male combat veterans, follow-up was three months, and the 35% cut-off has not yet been independently validated.
Danan et al. · Brain and Behavior · 2025Threshold effect for sustained symptom improvementRead the analysis ↗Doenyas-Barak et al. · 2024The original randomised, sham-controlled PTSD trialRead the RCT ↗
PTSD needs specialist care. HBOT remains an investigational adjunct for PTSD and should not replace trauma-focused psychological treatment, medication when indicated, or urgent mental-health support.
Post-COVID condition · human clinical studies
What has HBOT research found in people with long COVID?
Post-COVID condition can involve brain fog, fatigue, sleep disturbance, mood symptoms, pain and exercise intolerance months after the original infection.
A connected group of studies tested whether a defined HBOT course could influence symptoms, cognitive performance, brain imaging and selected cardiac measures.
01 · strongest designDouble-blind, sham-controlled RCTshort-term cognition, symptoms and brain imaging
→02 · secondary analysisCardiac ultrasound measuresfull sample and reduced-strain subgroup
→03 · durability signalOne-year observational follow-uptreated participants only; no long-term control
Study 1 · randomised controlled trial
Forty sessions produced measurable changes beyond sham.
Seventy-three adults with post-COVID symptoms lasting at least three months were randomised to HBOT or a sham chamber exposure. Outcomes were reassessed one to three weeks after the final session.
37 HBOTvs36 sham
cognitionenergysleepmoodpain
Symptoms and imaging moved together
The findings were not limited to questionnaires.
The RCT also reported changes in regional brain perfusion and microstructure on MRI. The affected regions were involved in attention, executive function, movement, sensory processing and emotional regulation.
Plain-English interpretation: clinical improvements occurred alongside measurable brain changes—but the study cannot prove that every symptom was caused by a single brain mechanism.
The protocol tested
This evidence belongs to a specific dose.
40 sessions5× each week2 ATA pressure90 min oxygen exposure5 min air break every 20 minutes
Study 2 · cardiac RCT analysis
A possible signal in people with reduced cardiac strain.
Sixty participants had usable cardiac imaging. Across the full analysis, the between-group mixed-model result was not significant. In the 29-person subgroup with reduced global longitudinal strain at baseline, improvement favoured HBOT (group-by-time p = 0.041).
This subgroup result is encouraging, but it was post-hoc and needs confirmation in a prospectively selected cardiac population.Read the cardiac study ↗Study 3 · longitudinal follow-upMany reported gains were still present about one year later.
Thirty-one treated participants were reassessed an average of 486 days after their final HBOT session. Improvements in quality of life, sleep, psychiatric symptoms and pain remained similar in magnitude across many domains.
There was no untreated or sham comparison at long-term follow-up, so durability is suggested—not proven against natural recovery.Read the follow-up study ↗What this body of research supports
A 40-session HBOT protocol produced short-term improvements over sham in several cognitive and symptom measures, accompanied by brain-imaging changes. Follow-up data suggest that some improvements may persist.
What remains uncertain
The trials were relatively small and came from one research programme. Long COVID is biologically diverse, long-term controlled evidence is absent, and the cardiac benefit was limited to a post-hoc subgroup. Larger independent multicentre trials are needed.
Long COVID needs individual assessment. HBOT remains an investigational adjunct and should not replace medical evaluation for cardiac, respiratory, neurological or clotting problems, nor established symptom-directed rehabilitation.
Erectile dysfunction · human clinical evidence
Could better oxygen delivery support erectile function?
An erection depends on healthy blood vessels, nerves, hormones and psychological wellbeing. HBOT may be most relevant when reduced blood flow is part of the problem—but the same symptom can have very different causes.
That makes diagnosis more important than the treatment label.
The main positive study
A promising signal—but not yet proof.
In a 2018 prospective study, 30 men with longstanding erectile dysfunction completed 40 HBOT sessions. Erectile-function scores improved and most participants reported better erections.
40 sessions2 ATA pressure90 min per session30 completers
The proposed idea
Support the living tissue and its small blood vessels.
HBOT greatly increases oxygen dissolved in plasma. Repeated exposures may influence signals involved in new small-vessel growth and improve tissue perfusion. In the 2018 study, penile MRI findings were consistent with increased blood flow—but only seven men had this scan, so this remains a hypothesis-generating result.
Prospective cohort · 50 men
Scores rose from 15.74 to 19.50.
A 2018 study reported improvement across erectile-function questionnaire domains after HBOT. The men received HBOT for various medical conditions, and there was no sham or untreated control.
Read the Sahin study ↗Pre/post cohort · 43 menFunction improved; testosterone did not.
IIEF erectile-function scores increased from 20.6 to 25.4. Total and free testosterone did not change significantly, suggesting the reported effect was not a testosterone boost.
Read the Sen study ↗A different cause, a different result
The placebo-controlled prostate-surgery trial was negative.
In a randomised, double-blind trial of 109 men after nerve-sparing radical prostatectomy, HBOT did not improve erectile recovery compared with placebo at 18 months. Post-surgical nerve injury is not the same as chronic vascular erectile dysfunction, but this result shows HBOT cannot be assumed to help every form of ED.
What the research suggests
Small uncontrolled human studies provide an encouraging early signal for selected men, particularly where vascular function may be relevant.
What it does not establish
There is not yet a positive sham-controlled RCT proving HBOT treats chronic vascular ED. Durability, ideal patient selection and the added value beyond standard care remain uncertain.
Erectile dysfunction deserves a proper medical assessment. It can be an early sign of cardiovascular disease or diabetes. HBOT is investigational for ED and should not replace cardiovascular risk assessment, medicine review, diabetes care, hormonal testing when indicated, established treatments such as PDE5 inhibitors, or advice from a GP or urologist.
Fibromyalgia & ME/CFS · emerging clinical evidence
When pain, fatigue and brain signalling stay turned up.
Fibromyalgia and ME/CFS can overlap, but they are not the same illness. Fibromyalgia is dominated by widespread pain and altered pain processing. ME/CFS is defined by a marked loss of function and post-exertional malaise—a delayed worsening after physical or mental effort.
The nervous system’s “volume” may be too high.
Touch or pressure that should feel ordinary can be processed as painful. Poor sleep, fatigue and brain fog often travel with it.
Sharedpain
fatigue
sleep
brain fog
fatigue
sleep
brain fog
Activity can carry a delayed biological cost.
Post-exertional malaise may appear hours later and last days or longer. “Pushing through” can make symptoms worse.
Fibromyalgia · 2026 randomised crossover trial
HBOT plus standard care outperformed standard care alone.
Fifty-six women were randomised to early or delayed HBOT. During the first eight weeks, the group receiving HBOT alongside education, exercise and medicines improved more than the group receiving standard care alone.
56 randomised2.3 ATA pressure90 min per session32–40 sessions
Mota Neto et al. · BMJ Open · 2026Read the HOTFy randomised trialOpen study ↗
What to keep in perspective
This was a single-centre, open-label study: participants knew when they were receiving HBOT, 44 of 56 completed, and one author reported a financial interest in a hyperbaric centre. Some benefits reduced after treatment stopped, so durability remains uncertain.
Fibromyalgia · wider evidence
Several trials point in the same direction—but the studies are still small.
2015 · randomised crossover trial60 women
After 40 sessions at 2 ATA, symptoms, quality of life and pain-related brain activity improved; no improvement occurred during the no-treatment control period.
Read the study ↗2024 · randomised active comparison48 analysedFor a specific subgroup with childhood-trauma-related fibromyalgia, 60 HBOT sessions produced greater improvement in fibromyalgia impact than pregabalin or duloxetine.
Read the study ↗2023 · meta-analysis4 RCTs · 163 participantsPooled results favoured HBOT for fibromyalgia impact and tender-point count, but not for the pooled pain outcome. Side effects were more frequent with HBOT, though serious events were not reported.
Read the review ↗ME/CFS · 2026 prospective cohort
Encouraging changes—now needing a controlled trial.
Thirty people with moderate-to-severe post-infectious ME/CFS completed 40 HBOT sessions. Physical function, fatigue, pain, processing speed, exercise capacity and grip strength improved from baseline. Functional MRI also showed thalamic connectivity moving towards the pattern seen in healthy controls.
Important: the healthy group was used for brain-imaging comparison—not as an untreated clinical control. Without a sham or no-treatment group, the study cannot separate HBOT from natural change, expectation, repeated testing or other care.
The ME/CFS protocol tested
Flexible pacing mattered.
40 sessions2 ATA pressure90 min oxygen5 min air breaks every 20 minutes8–16 weeks to finish
PEM
Kim et al. · Journal of Translational Medicine · 2026HBOT improves clinical symptoms and functional capacity and modulates thalamic connectivity in ME/CFSRead the full study ↗ME/CFS is not ordinary tiredness.
Participants often needed days off between sessions to prevent symptom worsening. The study excluded people too unwell to leave home, so its findings should not be extended to severe or very severe ME/CFS. Treatment plans must respect the person’s energy envelope; HBOT should never be paired with forced exercise or “push through” advice.
The balanced conclusion
Fibromyalgia now has several positive small randomised trials, including an encouraging 2026 crossover study. ME/CFS has a promising contemporary cohort, but no convincing sham-controlled evidence yet. Neither condition is currently a universally accepted indication for HBOT.
Clinical care still comes first
Assessment should exclude other causes of pain or fatigue and review sleep, medicines, anaemia, thyroid function, autoimmune disease and mental health where appropriate. HBOT should be considered only as a screened adjunct to individualised medical care.
Healthy ageing · randomised controlled trial
Can HBOT help an older brain work more efficiently?
In 2020, researchers studied healthy, independently living adults over 64—people without dementia, mild cognitive impairment or a previous brain disorder.
After three months, the HBOT group improved more than the no-treatment control group in global cognition, with the clearest changes in attention and information-processing speed.
63healthy adults randomised
→3 monthsHBOT or no-treatment control
→1–2 weeks latercognition and brain perfusion reassessed
What changed?
The largest improvements were in skills used every day.
The study reported a significant group-by-time improvement in global cognitive function. The clearest gains were in staying focused, handling information quickly and switching efficiently between tasks.
Overall cognitive performance improved significantly compared with control.
The ability to maintain and direct attention showed one of the clearest changes.
Participants processed and responded to information more quickly after HBOT.
Frontal regionsMotor-planning regionsParietal region
The result was not only a test score
Brain scans also detected increased regional blood flow.
Perfusion MRI showed increased cerebral blood flow in selected frontal, supplementary motor and parietal regions. These regions contribute to attention, planning, task switching, working memory and processing information.
In plain English: the cognitive improvements occurred alongside measurable changes in blood delivery to brain areas involved in those same abilities.
The protocol used
This was a substantial treatment course—not a few occasional sessions.
60 sessions5× each week2 ATA pressure90 min oxygen by mask5 min air break every 20 minutes
What the study supports
A defined HBOT course was associated with improved cognition and regional brain perfusion in this selected group of healthy older adults.
What it does not prove
It does not show that HBOT prevents or treats dementia. The study was small, used a no-treatment rather than sham control, participants knew their group, and long-term durability was not established.
Healthy ageing · human research
Can HBOT reverse ageing?
Not in the way that phrase is usually understood. Ageing is not one switch that can be turned backwards. It is a collection of changes affecting cells, blood vessels, immunity, repair systems, organs and function.
Human studies suggest a specific HBOT course can influence some ageing-related markers. They do not show that a person’s whole biological age has been reversed.
A change at one level does not automatically prove the next. A longer telomere in one blood-cell type is scientifically interesting, but it is not the same as a younger heart, a prevented dementia or extra years of life.
Study 1 · telomeres and immune-cell senescence
Blood-cell markers moved in a younger-looking direction.
Thirty healthy adults aged 64 or older completed 60 HBOT sessions. Researchers measured telomere length in several types of immune cells and the proportion of senescent T cells.
Telomeres increased by more than 20% in several immune-cell populations. Senescent T-helper cells decreased by about 37%, while senescent cytotoxic T cells decreased by about 11%.
30 completers60 sessions2 ATA pressure90 min oxygen exposure
Before
more senescent T cells
→shorter measured ends
more senescent T cells
After course
fewer senescent T cells
longer measured ends
fewer senescent T cells
Why this is not proof of age reversal
Hachmo et al. · Aging · 2020HBOT increases telomere length and decreases immunosenescence in isolated blood cellsRead the full study ↗The study had no untreated or sham comparison group. Telomere analysis included 26 people and senescent-cell analysis included 20. Measurements were taken from selected circulating immune cells—not every tissue—and follow-up was only one to two weeks after the final session. We do not know whether the changes lasted or improved long-term health.
Surface
collagenelastic fibressmall vessels
Study 2 · skin biopsies
Researchers saw structural changes inside ageing skin.
Thirteen healthy men, averaging 68 years old, provided repeated skin biopsies after a three-month control period and again after HBOT. Following treatment, collagen density, elastic-fibre length and blood-vessel number increased, while fibre fragmentation and tissue senescent cells decreased.
What this means: HBOT was associated with measurable microscopic tissue changes. The study did not test whether people looked younger, healed faster or maintained these changes over time.
What has actually been studied in humans?
A small map—not a complete picture.
The encouraging interpretation
Repeated, intermittent hyperoxia may trigger adaptive signalling involving blood-vessel growth, mitochondrial responses, inflammation and cellular repair. Small human studies show changes in brain function, immune-cell markers and skin tissue.
The scientifically careful interpretation
These findings are early, come largely from one centre and use a substantial 60-session protocol. Biomarker changes are not validated proof of whole-body rejuvenation, lower disease risk or longer life.
Healthy ageing still begins with the foundations. Exercise, sleep, blood-pressure control, not smoking, balanced nutrition, social connection and appropriate medical screening have much stronger evidence for protecting healthspan. HBOT should be viewed as an investigational adjunct—not a replacement for them.
The balanced explanation
HBOT is an adjunct—not a cure.
Brain injury can disturb oxygen delivery, inflammation, electrical balance and mitochondrial energy production. HBOT temporarily increases plasma-dissolved oxygen and may support viable but stressed tissue. Repeated treatments may also influence inflammation, vascular signalling and neuroplasticity.
Some trials report improvement, particularly for persistent post-concussion symptoms, while others do not. HBOT does not replace emergency stroke care, neurological assessment or rehabilitation.
Discuss an assessment →Cancer, metabolism & radiation recovery
Two different questions need two different answers.
Research into HBOT as part of a metabolic approach to cancer is early and largely preclinical. Using HBOT to help selected late radiation tissue injuries is a separate, recognised clinical application. Neither should interrupt or replace cancer treatment.
Thomas Seyfried’s research framework
Can cancer’s altered metabolism be targeted?
Seyfried proposes that impaired mitochondrial energy metabolism is central to cancer and describes a “press–pulse” strategy: sustained metabolic pressure, such as reduced glucose availability, combined with treatment pulses aimed at additional tumour vulnerabilities.
HBOT enters this theory because low-oxygen regions can support tumour adaptation and treatment resistance. Increasing oxygen may alter that environment—but a plausible mechanism is not proof of benefit in people.
What the frequently cited experiment found
Ketogenic diet plus HBOT prolonged survival in mice.
In a 2013 metastatic-cancer mouse model, the ketogenic diet slowed tumour growth. HBOT alone did not influence cancer progression, while the combined diet-and-HBOT group had slower measured tumour growth and longer mean survival than controls.
Important boundary
This was an animal experiment—not a human clinical trial. It does not establish HBOT, a ketogenic diet, or their combination as an effective cancer treatment in patients.
Read the mouse study ↗Read Seyfried’s press–pulse paper ↗HBOT is not a substitute for oncology care.
Anyone with active cancer should discuss HBOT with their oncologist and hyperbaric physician. Timing matters—particularly around chemotherapy, radiotherapy, surgery and medicines that may affect oxygen safety or wound healing.
A recognised clinical use
How HBOT may help tissue damaged by radiation.
Radiotherapy is designed to damage cancer cells, but months or years later some nearby normal tissue can become poorly supplied by small blood vessels. The tissue may be low in oxygen, fibrotic and less able to heal after minor injury or surgery.
Repeated HBOT sessions temporarily raise tissue oxygen and may stimulate signals involved in new small-vessel growth, collagen turnover and wound repair. The aim is to improve the condition of living irradiated tissue—not to treat the original cancer.
- Radiation cystitis affecting the bladder
- Radiation proctitis affecting the bowel
- Soft-tissue radionecrosis
- Osteoradionecrosis, particularly of the jaw
- Selected non-healing surgical wounds in irradiated tissue
A 2023 Cochrane review found that HBOT may improve outcomes in selected late radiation injuries, while certainty and benefit vary by tissue and outcome. It is not appropriate for every post-radiation symptom, and specialist diagnosis remains essential.
The plain-English takeaway: HBOT for cancer metabolism is experimental; HBOT for carefully diagnosed delayed radiation tissue injury is established specialist practice. They are not the same claim.
Read the evidence
Promising science.
Precise language.
Research findings depend on the condition, protocol and population studied. These papers illustrate active research; they do not establish that every person will benefit.
HBOT · Human studyCognitive enhancement of healthy older adults using hyperbaric oxygenHadanny et al., 2020Read ↗Red light · Human studyLight stimulation of mitochondria reduces blood glucose levelsPowner et al., 2024Read ↗PBM · Clinical studyPhotobiomodulation and mitochondrial stimulation in human tissueModena et al., 2023Read ↗
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Safety is the treatment foundation
Advanced therapies need disciplined boundaries.
01Screen firstHistory, medicines, contraindications and intended outcome are reviewed.
02Measure the dosePressure, oxygen, wavelength, intensity and timing are treatment variables.
03Review the responseProgress and tolerance are reassessed as the evidence changes.
Wellington · New Zealand
Begin with a conversation,
not a conclusion.
Tell us what you are trying to understand or improve. We’ll explain what may fit, what may not, and what needs clinical oversight.
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