Clinical Evidence

Indications

HBOT applications across the evidence spectrum — from standard-of-care conditions approved by the UHMS to emerging investigational uses with preliminary clinical evidence.

UHMS-Approved Indications

The Undersea and Hyperbaric Medical Society (UHMS) lists 15 indications for which HBOT is an approved standard or adjunctive treatment (Indications Manual, 15th edition); 13 of them are also on the US FDA's list of conditions for which hyperbaric chambers are cleared. Evidence levels range from A (strong RCT evidence) to B (observational/expert consensus).

Acute Ischemias

1 Level A

Acute Ischemias

Air or Gas Embolism

Intravascular gas bubbles causing arterial obstruction. HBOT reduces bubble volume and promotes nitrogen elimination.

Standard of Care

4 Level A

Acute Ischemias

Crush Injury & Compartment Syndrome

Reduces post-ischemic edema, preserves threatened tissue, and accelerates healing in traumatic crush injuries.

Standard of Care

12 Level B

Acute Ischemias

Compromised Skin Grafts & Flaps

Salvage therapy for ischemic skin grafts and flaps. Reduces hypoxic necrosis and promotes graft survival through enhanced oxygenation.

Standard of Care

Toxicities

2 Level A

Toxicities

Carbon Monoxide Poisoning

HBOT accelerates CO elimination from hemoglobin and cytochrome oxidase, preventing delayed neurological sequelae.

Standard of Care

Infectious Diseases

3 Level A

Infectious Diseases

Clostridial Myositis & Myonecrosis (Gas Gangrene)

HBOT is directly lethal to Clostridium perfringens and inhibits toxin production, used adjunctively with surgery and antibiotics.

Standard of Care

8 Level B

Infectious Diseases

Intracranial Abscess

Adjunctive therapy for brain abscesses, particularly those caused by anaerobic organisms. Enhances antibiotic efficacy and immune response.

Standard of Care

9 Level A

Infectious Diseases

Necrotizing Soft Tissue Infections

Adjunctive treatment for necrotizing fasciitis and Fournier's gangrene, reducing mortality and tissue loss when combined with surgery.

Standard of Care

10 Level A

Infectious Diseases

Refractory Osteomyelitis

Chronic osteomyelitis unresponsive to conventional therapy. HBOT enhances leukocyte killing, promotes angiogenesis in avascular bone.

Standard of Care

Gas/Bubble Disorders

5 Level A

Gas/Bubble Disorders

Decompression Sickness

Primary treatment for nitrogen bubble formation in divers and compressed-air workers. Reduces bubble volume and promotes nitrogen elimination.

Standard of Care

Wound Healing

6 Level A

Wound Healing

Enhancement of Healing in Selected Problem Wounds

Adjunctive treatment for chronic non-healing wounds, particularly diabetic foot ulcers with transcutaneous oxygen measurements <40 mmHg.

Standard of Care

11 Level A

Wound Healing

Delayed Radiation Injury (Soft Tissue & Bony Necrosis)

Treatment for osteoradionecrosis and soft tissue radiation necrosis. Promotes angiogenesis in hypoxic, hypovascular, hypocellular tissue.

Standard of Care

23 Level B

Wound Healing

Acute Thermal Burns

Severe thermal burns destroy skin and trigger swelling and reduced blood flow in the surrounding tissue, which can deepen the injury over the first days. Hyperbaric oxygen has been used as an adjunct to specialist burn care to limit this progression, reduce oedema and support healing. Acute thermal burn injury is on the UHMS list of approved indications, and the FDA has cleared hyperbaric chambers for severe and large burns treated at a specialised burn centre. The clinical evidence is limited. A Cochrane review found two eligible randomised trials, both of poor methodological quality: one reported no difference in length of stay, mortality or number of operations, the other a shorter healing time (a mean of 19.7 versus 43.8 days). The reviewers concluded that there is not sufficient evidence to support or refute HBOT for thermal burns (Villanueva 2004). A 2026 systematic review of 13 studies (566 patients) concluded that HBOT shows promise as an adjunct, improving healing and reducing complications, but that variable and inconsistent outcomes limit definitive conclusions (Molina-Vega 2026). US Medicare does not cover HBOT for thermal skin burns. Treatment protocols vary between burn centres and have not been standardised in trials.

Adjunct — limited evidence

Haematological Disorders

7 Level B

Haematological Disorders

Exceptional Blood Loss Anemia

When transfusion is not possible due to religious beliefs or unavailability, HBOT provides sufficient dissolved plasma oxygen to sustain life.

Standard of Care

Sensory Disorders

13 Level B

Sensory Disorders

Idiopathic Sudden Sensorineural Hearing Loss

Adjunctive treatment when corticosteroids fail. Reverses cochlear hypoxia and reduces endolymphatic hydrops.

Standard of Care

14 Level B

Sensory Disorders

Central Retinal Artery Occlusion

Emergency treatment to preserve retinal layers and improve visual acuity through reversal of retinal ischemia.

Standard of Care

Bone Disorders

24 Level B

Bone Disorders

Avascular Necrosis of the Femoral Head

In avascular (aseptic) necrosis, part of a bone loses its blood supply and dies; in the hip, the femoral head can eventually collapse, often leading to joint replacement. HBOT has been studied in early-stage disease as a way to relieve pain and support repair of the bone. The UHMS lists avascular necrosis among its approved indications (No. 15), but it is not on the US FDA's list of cleared uses and Medicare does not cover it. In a small double-blind randomised trial, 20 patients with Ficat stage II femoral head necrosis received 30 sessions of hyperbaric oxygen or compressed air over six weeks: pain improved significantly with oxygen after 20 treatments, and seven years later none had required hip replacement — although after six weeks the air group was offered oxygen, so long-term follow-up was not controlled (Camporesi 2010). A 2021 meta-analysis of 10 cohort studies (368 treated patients and 353 controls; seven of the studies from China) found significant clinical improvement with HBOT, but the benefit was not significant in non-Asian patients (Paderno 2021). A 2025 meta-analysis of 10 studies (568 participants) found improvement from baseline but no difference between HBOT and non-HBOT groups, and concluded that HBOT cannot be regarded as an effective treatment for early-stage femoral head necrosis (Cao 2025). The evidence is therefore conflicting and largely observational. One protocol studied — not a clinical recommendation — used two cycles of 30 daily sessions of 90 minutes at 2.5 ATA, with a 30-day break between cycles (Bosco 2018).

Contested evidence

Evidence levels follow UHMS grading criteria. US Medicare covers a narrower set of conditions (NCD 20.29): thermal burns and severe anaemia are excluded, and sudden hearing loss, central retinal artery occlusion, intracranial abscess and avascular necrosis are not on its covered list.

9 55 56

Emerging Evidence

Conditions where preliminary clinical evidence supports investigational use of HBOT. Evidence levels remain B or C; independent replication of single-group findings is generally awaited.

Post-Viral Syndromes

15 Level B

Post-Viral Syndromes

Long COVID

Persistent multisystem symptoms following acute SARS-CoV-2 infection — including fatigue, cognitive dysfunction ("brain fog"), sleep disturbance, and pain. A 2022 randomised controlled trial reported significant improvements in cognitive function, sleep, pain, and overall symptom burden after 40 HBOT sessions, with benefits sustained at one-year follow-up. The evidence base is currently anchored to a single research group; independent replication is awaited (HOT-LoCO trial in progress).

Emerging Evidence

Chronic Pain Syndromes

16 Level B

Chronic Pain Syndromes

Fibromyalgia

Chronic central sensitisation syndrome characterised by widespread pain, tender points, fatigue, sleep disturbance, and cognitive symptoms. A 2015 prospective controlled trial reported significant improvements in pain, tender points, quality of life, and brain activity patterns after 40 HBOT sessions at 2.0 ATA. Two independent 2023 meta-analyses pooled randomised data and confirmed improvements in function, tender points, fatigue, sleep, and quality of life — though the magnitude of pain reduction varied between pooled analyses. A separate 2023 RCT in fibromyalgia patients with a history of traumatic brain injury reported significant pain and symptom improvements with HBOT compared to pharmacological treatment (60 sessions, 2.0 ATA). The seminal RCT remains anchored to a single research group, but meta-analytic confirmation provides supporting evidence.

Emerging Evidence

Inflammatory Skin Disease

17 Level C

Inflammatory Skin Disease

Inflammatory Dermatoses

Case-level and small-cohort evidence supports HBOT as an adjunct in selected inflammatory skin conditions, primarily atopic dermatitis and psoriasis. A 2025 review and a 2021 paediatric study describe reductions in pruritus, lesion severity, and Staphylococcus aureus colonisation in severe atopic dermatitis after HBOT cycles. Two 2009 case reports document remission of psoriasis vulgaris with HBOT (one pustular/arthropathic case after 6 sessions at 2.8 ATA × 60 min; one plaque case improving after 15 sessions at 2.0 ATA × 90 min). Other inflammatory dermatoses — hidradenitis suppurativa, livedoid vasculopathy, pyoderma gangrenosum — have been described in early-stage clinical reports but lack robust supporting trials. Protocols vary widely and are not standardised; HBOT is positioned as adjunctive, not first-line.

Emerging Evidence

Aesthetic & Reconstructive Surgery

18 Level B

Aesthetic & Reconstructive Surgery

Aesthetic & Reconstructive Recovery

Adjunctive HBOT in aesthetic and reconstructive surgery for accelerated post-procedure healing and salvage of compromised grafts and flaps. A 2023 case–control study of facelift patients (n=20, retrospectively matched, single surgeon) reported mean wound healing of 13.3 days in the HBOT group versus 36.9 days in matched controls (P<.001), with sessions starting within 24 hours of surgery at approximately 2.0 ATA. Reviews of compromised flaps and grafts characterise HBOT as a salvage adjunct that improves oxygen delivery, angiogenesis, fibroblast activity, and edema control while standard surgical management addresses the mechanical cause of failure. HBOT is positioned as a salvage and recovery adjunct, not as a routine enhancer of uncomplicated cosmetic surgery.

Emerging Evidence

Reproductive Health

19 Level C

Reproductive Health

Endometriosis

Endometriosis is an emerging investigational application of HBOT. Translational evidence in rodent models supports an anti-inflammatory effect on endometriotic lesions: a 2011 rat study reported lesion remission with HBOT, and a 2022 mouse-model study reported reduction of inflammatory markers. Clinical evidence in humans is awaited — the HEROES randomised trial (Sunnybrook Health Sciences Centre, NCT06579040, recruiting since April 2025) is currently underway to evaluate HBOT for endometriosis-related pain. HBOT is positioned as an investigational adjunct, not standard of care.

Investigational

Neuropsychiatric

20 Level B

Neuropsychiatric

Post-Traumatic Stress Disorder (PTSD)

Post-traumatic stress disorder (PTSD) is a trauma- and stressor-related disorder marked by intrusive memories, avoidance, hyperarousal, and altered mood and cognition, with documented changes in brain activity and white-matter integrity. A specific HBOT protocol has been studied as a means of inducing neuroplasticity in established, often treatment-resistant PTSD; rather than acting pharmacologically, it is proposed to drive neuroplasticity through the hyperoxic-hypoxic paradox, accompanied in trials by improved resting-state functional connectivity across the default-mode, central-executive and salience networks (2024) and increased white-matter fractional anisotropy in fronto-limbic tracts, the genu of the corpus callosum and the fornix on diffusion tensor imaging (2022). A randomised, sham-controlled trial in 56 combat veterans (60 sessions, 90 minutes, 100% O₂ at 2 ATA) found CAPS-5 scores fell from 42.6 to 25.8 with HBOT while the sham group did not improve; an earlier randomised controlled trial in treatment-resistant PTSD showed concordant symptom and neuroimaging improvements; a 2026 systematic review and meta-analysis pooled two sham-controlled PTSD RCTs and reported a large effect while cautioning that studies are small and preliminary; and a 2026 prospective observational cohort of 50 US veterans reported reductions sustained to six months. The investigational protocol as studied — not a clinical recommendation — comprised 60 daily sessions of 90 minutes, 100% oxygen at 2 ATA, with intermittent air breaks. The randomised evidence originates substantially from a single research group (Sagol Center / Shamir Medical Center) — the same lineage as the Long COVID and Fibromyalgia entries — though, unlike those, there is now early independent corroboration (a US observational cohort and a meta-analysis by an unaffiliated group). Sample sizes remain small and larger multicentre randomised trials are needed. HBOT for PTSD remains investigational and is not FDA-approved.

Emerging Evidence

Acquired Brain Injury

21 Level B

Acquired Brain Injury

Chronic Post-Stroke Recovery

Many stroke survivors retain motor, sensory and cognitive deficits long after the acute event, and gains from conventional rehabilitation typically plateau in the months that follow. HBOT has been studied in this chronic phase as a way to reactivate neuroplasticity in brain regions that remain alive but under-functioning. A prospective randomised trial enrolled 74 patients 6–36 months after stroke, of whom 59 were analysed (Efrati 2013): one group received 40 HBOT sessions (90 minutes, 100% oxygen at 2 ATA, five days a week), while the other served as a two-month no-treatment control before crossing over to the same HBOT course. Neurological function (NIHSS), activities of daily living and quality of life improved significantly after HBOT but not during the control period, and SPECT showed increased activity mainly in regions that appeared viable on CT yet had low metabolic activity. An independent randomised feasibility trial in Toronto, in 27 patients 3–48 months after stroke (Schiavo 2020), found HBOT combined with an upper-limb exercise and mental-imagery programme safe and feasible, with trends toward improved upper-limb motor function; differences between the groups were not statistically significant. This chronic-phase evidence should be distinguished from acute stroke: a Cochrane systematic review of 11 randomised trials involving 705 participants found no good evidence that HBOT improves clinical outcomes when applied during the acute presentation of ischaemic stroke, while noting that the possibility of benefit has not been excluded (Bennett 2014). The principal chronic-phase trial had no sham control, so participants knew their allocation, and it comes from the same Israeli research group (Assaf Harofeh, now Shamir Medical Center) as the Long COVID, Fibromyalgia and PTSD entries. The protocol as studied — not a clinical recommendation — comprised 40 daily sessions of 90 minutes, 100% oxygen at 2 ATA, five days a week. HBOT for stroke recovery remains investigational and is not FDA-approved.

Emerging Evidence

22 Level B

Acquired Brain Injury

Traumatic Brain Injury & Post-Concussion Syndrome

After a mild traumatic brain injury (concussion), a minority of patients develop persistent post-concussion syndrome — headache, slowed thinking, memory and attention problems and mood changes that can last for years. HBOT in this chronic phase is one of the most contested questions in hyperbaric medicine, and the trials point in different directions. In favour: a randomised crossover trial in 56 adults 1–5 years after mild TBI (40 sessions of 60 minutes, 100% oxygen at 1.5 ATA) reported significant improvements in cognitive function and quality of life after HBOT but not during a no-treatment control period, with SPECT showing increased brain activity (Boussi-Gross 2013); and a sham-controlled, double-blind trial in 25 children aged 8–15 with persistent post-concussion syndrome (60 sessions of 60 minutes at 1.5 ATA, against a sham at near-surface pressure) reported improvements in cognitive and behavioural function, symptoms and quality of life, with MRI microstructural changes, although recruitment stopped before the planned sample size was reached (Hadanny 2022). Against: a randomised, double-blind, sham-controlled trial in 60 active-duty marines with post-concussion symptoms persisting 3–36 months (40 sessions of 60 minutes) found no immediate benefit of oxygen exposures equivalent to 1.5 or 2.0 ATA over a sham gas mixture equivalent to breathing surface air, and concluded that the results do not support HBOT for cognitive, balance or fine-motor deficits (Walker 2014). Interpretation hinges on the control arms. One review argues that pressurised-air controls (21% oxygen above 1.0 ATA, typically 1.2–1.3 ATA) are themselves therapeutically active, so trials using them are better read as dose comparisons, and grades the evidence as B-level (Figueroa & Wright 2016); a critical appraisal counters that no mechanism has been shown for such low-pressure exposures and that an apparent effect in both arms more likely reflects a participation effect (Bennett 2018). Both positive trials come from a single Israeli research group (Assaf Harofeh, now Shamir Medical Center), and several authors of the 2022 trial declare commercial competing interests. The protocols studied — not a clinical recommendation — comprised 40–60 daily sessions of 60 minutes, 100% oxygen at 1.5 ATA, five days a week. HBOT for TBI and post-concussion syndrome remains investigational and is not FDA-approved.

Emerging Evidence (contested)

These indications are not on the UHMS list of approved indications or the FDA's list of cleared uses, and are not covered by Medicare in the United States. They are presented for clinical context; treatment decisions require individual evaluation.