Hyperbaric oxygen therapy sits in a uniquely difficult spot in medicine — solid evidence for the 14 UHMS-recognized indications, promising but contested evidence for several emerging uses, and a sprawling wellness market selling protocols with no clinical clearance at all.
This guide synthesizes what the highest-quality 2023-2025 clinical research actually says about HBOT. We pulled findings from Cochrane reviews, systematic reviews, randomized controlled trials, and the active CMS and FDA regulatory documents.
What Is Hyperbaric Oxygen Therapy?
Hyperbaric oxygen therapy delivers 100% oxygen inside a pressurized chamber at 1.5-3.0 atmospheres absolute (ATA). The elevated pressure forces oxygen to dissolve directly into blood plasma rather than relying only on hemoglobin binding.
Per Henry's Law, dissolved plasma oxygen rises roughly 15-fold at 2.0 ATA breathing pure oxygen compared to room air at sea level. This dissolved oxygen perfuses tissues that have compromised blood flow — the foundation for HBOT's wound-healing indications.
The UHMS 13th Edition Indications (2024) is the medical reference document insurers and CMS rely on for medical-necessity determinations.
How HBOT Works at a Cellular Level
Increased tissue oxygenation supports mitochondrial ATP production and cellular repair, while reducing edema and inflammation in injured tissue.
HBOT also activates hypoxia-inducible factor 1-alpha during reperfusion, increasing VEGF production and driving angiogenesis over 20-40 sessions per the Cochrane HBOT for Chronic Wounds review (2024).
It mobilizes CD34+ stem cells from bone marrow — a Thom et al. 2006 study in the American Journal of Physiology found a single session doubled circulating counts and 20 sessions raised them 8-fold.
These mechanisms underlie the FDA-cleared indications. Their relevance to off-label uses is plausible but less clinically established.
Safety Profile in Controlled Settings
The most common side effects are mild — middle-ear barotrauma during pressurization, transient myopic shift over 20-40 sessions that reverses within weeks, and mild fatigue.
Serious complications are rare in UHMS-accredited facilities. Oxygen toxicity seizures occur in fewer than 1 in 10,000 sessions at 2.0-2.4 ATA per StatPearls HBOT Contraindications (2024). The only absolute contraindication is untreated pneumothorax.
Fire risk is the catastrophic but preventable concern. The FDA Safety Communication (2021) documented 27 chamber fires globally between 1923-2018, every one tied to ignition sources brought into the chamber.
Does HBOT Help Post-Traumatic Stress Disorder?
The 2024 evidence base for HBOT in PTSD is the strongest it has ever been, though it comes with important caveats.
A 2024 systematic review by Andrews et al. in Frontiers in Neurology analyzed eight studies covering 393 subjects. The review found 40-60 HBOT sessions produced statistically significant symptomatic improvement at pressures from 1.3 to 2.0 ATA.
Cumulative oxygen doses ranged from 1,002 to 11,400 atmosphere-minutes. A linear dose-response relationship emerged — more oxygen exposure correlated with greater symptomatic gains.
Three of the eight included studies documented correlative brain imaging changes alongside symptomatic improvement, suggesting HBOT was driving measurable neurobiological change rather than placebo response. The PEDro Scale rated all seven randomized trials as good-to-highest quality.
The Emotional Exacerbation Signal
The dose-response curve also reveals a real safety concern.
Subjects receiving the highest cumulative oxygen doses experienced severe but reversible emotional symptom worsening in 30-39% of cases. This is not a minor finding — it directly informs how clinicians should structure PTSD protocols.
Andrews et al. concluded that PTSD "can no longer be considered strictly a psychiatric disease," given the imaging evidence and HBOT's measurable effects. But the same review emphasized that careful dose titration and active psychological monitoring during the protocol are essential.
The ongoing USF Health $28M state-funded TBI/PTSD trial launched in 2024-2025 is enrolling veterans specifically to study biomarkers predicting which patients are at greatest risk for the emotional exacerbation effect.
Practical Implications
For PTSD patients considering HBOT, the 2024 evidence supports clinical benefit when delivered under proper psychiatric supervision.
The treatment is not currently covered by insurance for PTSD — this is an off-label use under the FDA Safety Communication (2021, reaffirmed 2024) framework. Out-of-pocket cost for a 40-60 session protocol typically runs $6,000-$15,000.
Does HBOT Help Acute Ischemic Stroke?
The 2024 evidence for HBOT as an acute ischemic stroke adjunct is mixed and condition-specific. See the stroke recovery evidence atlas for the full investigational evidence breakdown.
A 2024 BMC Neurology meta-analysis by Li et al. pooled eight randomized controlled trials covering 493 patients. The analysis showed no statistically significant differences between HBOT and control groups on the National Institutes of Health Stroke Scale (NIHSS) or the Barthel index.
However, the meta-analysis did find a statistically significant improvement in the modified Rankin score (MD = 0.10, 95% CI 0.03 to 0.17) — a measure of post-stroke disability and dependence in daily activities.
Adverse event incidence at the end of treatment was actually lower in the HBOT group (OR = 0.42, 95% CI 0.19 to 0.94), though the effect did not persist at 6-month follow-up.
Inflammatory Marker Findings
The meta-analysis also tracked inflammatory markers including TNF-α, sICAM, sVCAM, sE-selectin, and CRP. No statistically significant HBOT effects emerged across these markers.
This suggests that whatever mechanism is producing the modified Rankin improvement, it's not primarily driven by systemic inflammation reduction in the immediate post-stroke window.
A February 2026 randomized double-blind sham-controlled trial in post-stroke depression has since extended this work, suggesting HBOT may modulate neurotrophic factors during stroke recovery — a mechanism that could eventually help explain the modified Rankin signal.
What This Means for Patients
For acute ischemic stroke, the 2024 evidence supports HBOT as a low-harm adjunctive therapy with modest functional benefit. It is not a substitute for tissue plasminogen activator (tPA) or mechanical thrombectomy within the standard treatment windows.
The benefit on modified Rankin score is real but small in magnitude. Patients and clinicians should weigh this against the cost and time commitment of a multi-session protocol.
What About Long COVID and Post-Viral Cognitive Dysfunction?
The strongest emerging-indication evidence is for long COVID and post-viral cognitive dysfunction.
A 2025 Scientific Reports randomized double-blind trial by Zilberman-Itskovich et al. studied 73 patients with post-COVID condition. After 40 HBOT sessions at 2.0 ATA, the treatment group showed statistically significant improvements in cognitive function, sleep quality, psychiatric symptoms, and pain interference — with benefits persisting at 1-year follow-up.
The mechanism is hypothesized to involve neuroplasticity stimulation and reduction of post-viral neuroinflammation, building on the Boussi-Gross et al. 2013 PLOS One study that first demonstrated HBOT-induced neuroplasticity in chronic stroke patients.
Long COVID HBOT is currently off-label and not covered by insurance per the FDA Safety Communication (2021, reaffirmed 2024). A 40-session protocol typically runs $8,000-$14,000 at independent clinics.
What About Traumatic Brain Injury?
HBOT for TBI is the most actively researched off-label indication, with several large trials ongoing.
The federally registered NCT02407028 trial is comparing HBOT to sham HBOT in U.S. service members and veterans aged 18-75 who experienced mild-to-moderate TBI at least one year prior. The randomized double-blind design represents the gold standard for HBOT-TBI evidence.
The USF Health $28M state-funded HBOT-TBI trial launched its first Florida veteran participants in 2024-2025 and ranks among the most rigorous HBOT-TBI studies in the country.
A 2024 BMC Neurology paper noted parallel mechanistic findings supporting plausibility of TBI benefit, though results from the major trials are not yet published.
For now, HBOT for TBI is off-label. The 2024-2025 trial readouts will determine whether it should become an FDA-cleared indication.
Anti-Aging, Senescence, and Telomeres
The most-cited anti-aging HBOT research is the Hachmo et al. 2020 Aging study, which reported that 60 HBOT sessions in healthy adults aged 64+ lengthened telomeres by up to 20% and cleared senescent cells by up to 37%.
This is a small open-label study (35 subjects, no control group) and the findings have not yet been independently replicated at scale. The mechanism is biologically plausible but the clinical significance is unsettled.
The 2020 Aging paper is the basis for a substantial wellness-clinic market selling anti-aging HBOT protocols at $200-$500 per session.
Patients considering anti-aging HBOT should know that this is an off-label use with promising but limited evidence. The FDA Safety Communication (2021) does not recognize anti-aging as an HBOT-cleared indication.
The 14 FDA-Cleared Indications
These are the indications backed by the strongest clinical evidence, reimbursed by Medicare under CMS NCD 20.29 (active 2026), and reviewed in detail in the UHMS 13th Edition Indications (2024):
- Air or gas embolism
- Carbon monoxide poisoning
- Gas gangrene (clostridial myositis and myonecrosis)
- Crush injury and compartment syndrome
- Decompression sickness
- Diabetic wounds of the lower extremity (Wagner grade 3+)
- Exceptional blood loss anemia
- Intracranial abscess
- Necrotizing soft-tissue infections
- Chronic refractory osteomyelitis
- Delayed radiation injury (soft tissue and bony necrosis)
- Compromised skin grafts and flaps
- Acute thermal burn injury
- Idiopathic sudden sensorineural hearing loss
For these, the evidence is strong enough that withholding HBOT can constitute a deviation from standard of care.
The Cochrane HBOT for Chronic Wounds review (2024) specifically found HBOT reduced major amputation risk in patients with chronic diabetic foot ulcers — a finding driving inclusion in CMS coverage policy.
Active Clinical Trials Worth Watching
Several trials are likely to reshape the HBOT evidence base over the next 2-3 years:
- NCT02407028 (HOBIT/HOBIT-2) — the federally registered HBOT-TBI trial for service members and veterans
- USF Health $28M HBOT-TBI/PTSD trial — launched 2024-2025, targeting Florida veterans
- Post-stroke depression trial (2026) — extending the 2024 acute ischemic stroke evidence into the recovery window
- Long COVID extension trials — building on the Zilberman-Itskovich 2025 Scientific Reports findings
- Pediatric cerebral palsy HBOT — an open question that earlier small trials suggested merits larger investigation
For patients considering enrollment, ClinicalTrials.gov maintains the active study registry.
Frequently Asked Questions
Is HBOT FDA-approved?
HBOT is FDA-cleared for the 14 specific indications listed in CMS NCD 20.29 (active 2026) and the UHMS 13th Edition Indications (2024). It is not FDA-cleared for long COVID, TBI, PTSD, autism, cerebral palsy, or anti-aging. Off-label use is legal but not insurance-reimbursed and the FDA Safety Communication (2021, reaffirmed 2024) explicitly cautions against marketing HBOT for non-cleared uses. See the cerebral palsy evidence atlas for the full investigational evidence breakdown.
What does the highest-quality 2024-2025 HBOT research actually show?
For PTSD, the 2024 Frontiers in Neurology systematic review shows dose-dependent symptomatic improvement with a notable emotional-exacerbation risk at high doses. For acute ischemic stroke, the 2024 BMC Neurology meta-analysis shows modified Rankin improvement but no NIHSS or Barthel benefit. For long COVID, the 2025 Scientific Reports trial shows cognitive, sleep, and quality-of-life improvement with 1-year persistence.
Why don't most insurers cover HBOT for long COVID or TBI?
These are off-label uses under CMS NCD 20.29. The FDA Safety Communication (2021) is explicit that no HBOT device has been cleared for these indications, giving insurers a basis for denial. Commercial insurers follow Medicare's coverage determinations. The active TBI trials including NCT02407028 may eventually drive policy change.
How many sessions does the research support?
Indication-dependent. The Cochrane HBOT for Chronic Wounds review (2024) supports 20-40 sessions for diabetic foot ulcers. The 2025 long COVID trial used 40 sessions. The 2024 PTSD systematic review covered 40-60 session protocols. The Hachmo 2020 Aging study used 60 sessions.
What's the difference between hospital HBOT and wellness-clinic mild HBOT?
Hospital HBOT typically delivers 100% oxygen at 2.0-2.5 ATA in hard-shell chambers under physician supervision, billing the CMS NCD 20.29 rates. Wellness-clinic mild HBOT typically delivers concentrated (not 100%) oxygen at 1.3 ATA in soft-shell chambers without physician supervision. The mechanisms differ — most of the strong HBOT research has used 2.0+ ATA protocols, and the FDA Safety Communication (2021) cautions that mild HBOT may not produce the same physiologic effects.
Find HBOT Centers Near You
Browse our complete directory of UHMS-accredited HBOT centers to find a verified facility and confirm which indications they treat under physician supervision.
-- The HBOT Finder Team
Medical Disclaimer: This article is for informational purposes only and does not constitute medical advice. The 14 indications in CMS NCD 20.29 are FDA-cleared and insurance-reimbursable. Off-label uses including long COVID, TBI, PTSD, autism, and anti-aging carry promising but unsettled evidence and are not FDA-cleared per the FDA Safety Communication (2021). Always consult a qualified physician before beginning HBOT.
Editorial Disclosure: HBOT Finder maintains editorial independence. We do not accept paid placements in our directory.