TL;DR: A 2026 systematic review of 11 randomised controlled trials (480 participants) found that hyperbaric oxygen therapy (HBOT) consistently reduced pain intensity and improved quality of life in fibromyalgia patients. A 2023 meta-analysis reported a large effect on pain (SMD = -1.56). Canadian researchers at Toronto General Hospital confirmed feasibility and sustained benefits at three months. While promising, the evidence remains limited by small sample sizes and protocol variability, and larger trials are needed before routine clinical adoption.
What Is Fibromyalgia and Why Is HBOT Being Studied as a Treatment?
Hyperbaric oxygen therapy (HBOT) is a medical treatment that delivers 100% oxygen at pressures above normal atmospheric levels inside a pressurised chamber. Fibromyalgia is a chronic pain syndrome characterised by widespread musculoskeletal pain, fatigue, sleep disturbances, and cognitive impairment often called “fibro fog.” It affects an estimated 2-4% of the global population, with higher prevalence in women, and remains one of the most challenging conditions in modern rheumatology. Current pharmacological treatments – including pregabalin, duloxetine, and milnacipran – offer only partial symptom relief for most patients, and many individuals continue to experience significant disability despite multi-modal therapy.
HBOT typically uses pressures between 1.5 and 2.4 atmospheres absolute (ATA) and sessions lasting 60 to 90 minutes. Originally developed for decompression sickness and carbon monoxide poisoning, HBOT has attracted growing research interest as a neuromodulatory intervention for central sensitisation disorders like fibromyalgia. The proposed mechanism centres on HBOT’s ability to reduce neuroinflammation, promote neuroplasticity, and correct abnormal brain activity patterns in pain-processing regions. According to a 2024 review in Frontiers in Neurology, HBOT influences multiple cellular pathways including mitochondrial biogenesis, neurogenesis via Wnt-3 and VEGF/ERK signalling, synaptogenesis through elevated GAP43 expression, and anti-inflammatory responses through reduced TNF-alpha and IL-6 (Bin-Alamer et al., 2024).
This research summary, compiled by Canada Hyperbarics, examines the most current systematic reviews and randomised controlled trials evaluating HBOT for fibromyalgia, with particular attention to the landmark 2026 systematic review published in the Journal of Pain Research.
What Does the 2026 Systematic Review Show About HBOT for Fibromyalgia?
The most comprehensive evidence synthesis to date was published in March 2026 by Leys and colleagues at the University Hospital Antwerp. This PRISMA-guided systematic review examined 11 randomised controlled trials encompassing 480 participants with chronic pain syndromes, of which eight trials specifically evaluated fibromyalgia (Leys et al., 2026).
Key findings from the 2026 review include:
- Consistent within-group improvements in pain intensity, physical functioning, and quality of life across fibromyalgia trials
- Some studies demonstrated between-group superiority of HBOT over control interventions, though results were not uniform
- HBOT was generally well tolerated, with mostly mild adverse events (ear barotrauma, transient myopia)
- Methodological limitations were noted across trials, primarily due to subjective outcome measures and difficulty blinding participants to pressurised oxygen exposure
- Protocol heterogeneity (varying pressures, session counts, and durations) limits direct comparison between studies
The review authors concluded that “HBOT shows potential as an adjunctive intervention for selected chronic pain syndromes, particularly fibromyalgia,” while emphasising that “larger, standardised trials with extended follow-up are needed before routine clinical implementation can be recommended.”
How Strong Is the Meta-Analytic Evidence for Pain Reduction?
A dedicated meta-analysis published in BMJ Open by Chen and colleagues at West China Hospital provides the most granular quantitative evidence. This systematic review included nine clinical trials with 288 fibromyalgia patients and pooled data using random-effects models (Chen et al., 2023).
The meta-analysis reported a standardised mean difference of -1.56 (95% CI: -2.18 to -0.93, p < 0.001) for pain outcomes, representing a large treatment effect. Beyond pain reduction, the review found that HBOT improved tender point counts, fatigue severity, multidimensional functioning, patient global assessment, and sleep disturbance.
Adverse events occurred in 44 of 185 patients (23.8%), with 12 patients (6.5%) withdrawing due to adverse reactions. Importantly, no serious adverse events or complications were observed. The authors noted that pressures below 2.0 ATA may reduce adverse event rates, a finding with implications for protocol optimisation.
How Does HBOT Compare to Standard Medications for Fibromyalgia?
Two head-to-head randomised controlled trials from the Sagol Centre for Hyperbaric Medicine in Israel directly compared HBOT to FDA-approved medications (pregabalin and duloxetine), providing particularly valuable evidence.
In the first trial, Ablin and colleagues randomised fibromyalgia patients with a history of traumatic brain injury to either 60 sessions of HBOT (100% oxygen at 2 ATA, 90 minutes) or standard pharmacotherapy. HBOT produced a significant pain intensity reduction with a large effect size (Cohen’s d = -0.95) compared to medications. Brain SPECT imaging revealed increased activity in the left frontal and right temporal cortex, regions associated with executive function and emotional processing (Ablin et al., 2023).
The second trial by Boussi-Gross and colleagues focused on fibromyalgia patients with a history of childhood sexual abuse. Results showed an even larger treatment effect favouring HBOT over medications (Cohen’s d = -1.27), with SPECT imaging demonstrating increased activity in prefrontal and temporal brain areas. The authors attributed the improvements to HBOT’s neuroplasticity effects, suggesting that the therapy may address underlying neurological mechanisms rather than simply masking symptoms (Boussi-Gross et al., 2024).
What Has Canadian Research Contributed to HBOT for Fibromyalgia?
A noteworthy Canadian contribution comes from Toronto General Hospital’s Hyperbaric Medicine Unit. Curtis and colleagues conducted a feasibility study with 18 fibromyalgia patients randomised to either immediate HBOT or a 12-week delayed-treatment comparator. The protocol delivered 100% oxygen at 2.0 ATA, five days per week for eight weeks (Curtis et al., 2021).
The study confirmed that HBOT is feasible and safe for fibromyalgia patients in a Canadian clinical setting. Key outcomes included improved global functioning, reduced anxiety and depression symptoms, and improved sleep quality. Critically, these benefits were sustained at three-month follow-up, suggesting durable therapeutic effects rather than temporary relief. Adverse events included mild ear barotrauma in three patients and transient myopia in four patients, consistent with the known safety profile of HBOT.
For researchers interested in the broader evidence base for HBOT across conditions, the Canada Hyperbarics research library catalogues over 11,000 studies with AI-generated summaries and citation tools.
What Are the Proposed Mechanisms Linking HBOT to Fibromyalgia Improvement?
A 2025 narrative review by Pencalet, synthesising over 90 publications, identified several mechanistic pathways through which HBOT may benefit fibromyalgia patients (Pencalet, 2025):
- Central sensitisation reversal: HBOT may reduce hyperexcitability of pain-processing neurons in the spinal cord and brain, addressing the core pathophysiology of fibromyalgia
- Neuroplasticity and brain remodelling: SPECT imaging from multiple trials shows HBOT increases activity in prefrontal and temporal regions, suggesting structural and functional brain changes
- Anti-inflammatory effects: HBOT reduces pro-inflammatory cytokines (TNF-alpha, IL-6) and modulates immune responses, potentially addressing the neuroinflammation implicated in fibromyalgia
- Improved tissue oxygenation: Evidence suggests that reduced oxygen availability contributes to structural degeneration in fibromyalgia patients’ muscles, which HBOT may correct
- Mitochondrial function enhancement: HBOT promotes mitochondrial biogenesis and ATP production, potentially improving cellular energy metabolism in affected tissues
How Do the Key HBOT Fibromyalgia Trials Compare?
| Study | Year | Design | N | Protocol | Primary Finding |
|---|---|---|---|---|---|
| Leys et al. | 2026 | Systematic Review (11 RCTs) | 480 | Various | Consistent pain and function improvements; protocol heterogeneity limits conclusions |
| Chen et al. | 2023 | Meta-Analysis (9 studies) | 288 | Various | Large pain effect (SMD = -1.56); no serious adverse events |
| Boussi-Gross et al. | 2024 | RCT (HBOT vs meds) | 48 | 60 sessions, 2 ATA, 90 min | HBOT superior to medications (d = -1.27); brain activity changes on SPECT |
| Ablin et al. | 2023 | RCT (HBOT vs meds) | 48 | 60 sessions, 2 ATA, 90 min | Significant pain reduction (d = -0.95); improved quality of life |
| Curtis et al. | 2021 | Feasibility RCT | 18 | 40 sessions, 2.0 ATA | Feasible and safe in Canadian setting; benefits sustained at 3 months |
| Pencalet | 2025 | Narrative Review (90+ papers) | N/A | Various | Supports HBOT as promising adjunct; more research needed for dose-response |
What Are the Current Limitations and Research Gaps?
Despite encouraging results, several critical gaps remain in the HBOT-fibromyalgia evidence base:
- Small sample sizes: Individual trials range from 17 to 71 participants, limiting statistical power and generalisability
- Blinding challenges: Pressurised oxygen environments are difficult to mask from participants, introducing potential placebo effects
- Protocol variability: Pressures range from 1.5 to 2.4 ATA, sessions from 40 to 60, and treatment durations from 8 to 12 weeks, making optimal dosing unclear
- Limited long-term follow-up: Only the Canadian trial (Curtis et al.) reported three-month follow-up; longer-term durability remains unknown
- Geographic concentration: Most RCTs originate from a single research group in Israel, requiring independent replication
- Cost-effectiveness data absent: No published cost-effectiveness analyses exist for HBOT in fibromyalgia, a critical gap for health system decision-makers
- Regulatory status: Fibromyalgia is not among the 14 Health Canada-recognised conditions for HBOT, meaning treatment would typically not be covered by provincial health plans
For information on which conditions are currently covered by provincial health insurance, visit the Canada Hyperbarics coverage guide.
Frequently Asked Questions About HBOT and Fibromyalgia
Is HBOT an approved treatment for fibromyalgia in Canada?
Fibromyalgia is not currently among the 14 Health Canada-recognised conditions for HBOT. Some private clinics in Canada may offer HBOT for fibromyalgia on an off-label or investigational basis, but treatment costs would typically be out-of-pocket. Patients interested in exploring this option should consult the directory of hospitals and regulated facilities on Canada Hyperbarics.
How many HBOT sessions are typically used in fibromyalgia research?
Most clinical trials used protocols of 40 to 60 sessions delivered five days per week over 8 to 12 weeks. The Israeli RCTs used 60 sessions at 2 ATA for 90 minutes each, while the Canadian feasibility study used 40 sessions at 2.0 ATA. The optimal protocol has not yet been established through dose-finding studies.
What are the main side effects of HBOT in fibromyalgia patients?
According to the 2023 meta-analysis, adverse events occurred in approximately 24% of patients but were predominantly mild. The most common side effects include middle-ear barotrauma (pressure-related ear discomfort) and transient myopia (temporary near-sightedness that resolves after treatment ends). No serious adverse events were reported across the reviewed trials.
Is HBOT better than medication for fibromyalgia?
Two head-to-head RCTs found HBOT produced larger improvements than pregabalin and duloxetine, with effect sizes of d = -0.95 and d = -1.27 respectively. However, these trials had specific patient subgroups (TBI-related and CSA-related fibromyalgia), and the findings cannot be generalised to all fibromyalgia patients without further research.
Where can I find Canadian HBOT facilities?
Canada Hyperbarics maintains a comprehensive directory of hospitals and regulated facilities across all provinces, including both hospital-based programmes and private clinics that operate Health Canada-licensed chamber equipment.
What Comes Next for HBOT Fibromyalgia Research?
The 2026 systematic review by Leys et al. identifies several priority directions for future investigation. Large, multicentre RCTs with standardised HBOT protocols (fixed pressure, session number, and duration) are the most pressing need. Sham-controlled designs using slightly pressurised air would improve blinding credibility. Longer follow-up periods of 6 to 12 months would clarify whether HBOT’s benefits are durable. Economic evaluations comparing HBOT costs against long-term medication expenses and disability burden would inform health system funding decisions. Additionally, head-to-head comparisons with emerging non-pharmacological therapies (transcranial magnetic stimulation, low-dose naltrexone) would position HBOT within the broader landscape of fibromyalgia interventions. Biomarker studies examining inflammatory profiles, brain imaging changes, and genetic predictors of response could help identify which fibromyalgia patients are most likely to benefit from HBOT. Patient-reported outcome measures standardised across trials would also significantly improve evidence synthesis in future systematic reviews and meta-analyses.
Researchers can explore the full body of HBOT evidence across all conditions in the Canada Hyperbarics research library, which includes over 11,000 indexed studies with structured summaries and multiple citation formats.
This content is for informational purposes only and does not constitute medical advice. Hyperbaric oxygen therapy should only be administered by qualified healthcare professionals in accredited facilities. Patients considering HBOT for fibromyalgia should discuss the current evidence and their individual circumstances with their physician. For a list of regulated treatment centres across Canada, visit the Canada Hyperbarics facilities directory.
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