Hyperbaric oxygen therapy benefits: what the evidence supports

Hyperbaric oxygen therapy (HBOT) has well-documented benefits for a short list of medical problems, promising but unsettled evidence for several more, and little or no support for many of the uses it is marketed for online. Keeping those three groups apart is the most useful thing you can do before paying for sessions.

This guide explains what HBOT does in the body, where its benefits are established, where they are still being tested, and where controlled trials or UK guidance point the other way. Each result below comes with the kind of study behind it.

What does hyperbaric oxygen therapy do in the body?

HBOT means breathing concentrated oxygen while the pressure around you is higher than normal. NHS England describes it as the delivery of oxygen at a pressure greater than normal, so that a higher level of oxygen can be dissolved in the patient's blood plasma.

Pressure is measured in atmospheres absolute, written ATA. At sea level you live at about 1 ATA. Most of the oxygen in your blood travels on haemoglobin inside red blood cells, and in a healthy person that carrier is already close to full. Pressure changes the smaller portion that dissolves in plasma, the liquid part of blood.

Henry's law describes why: the amount of a gas that dissolves in a liquid rises in proportion to the pressure of that gas. A StatPearls review of hyperbaric physics gives the scale. Plasma carries roughly 3 mL of oxygen per litre at normal pressure, rising to about 60 mL per litre during HBOT at 3 ATA. The same review explains Boyle's law, which says a gas bubble shrinks as pressure rises. That is why pressure itself is part of the treatment for gas bubbles in the blood.

A mechanism is a reason to run trials, not a result. Whether extra dissolved oxygen helps a person has to be shown one condition at a time, at a stated pressure and number of sessions.

Where are the benefits of HBOT established?

The Undersea and Hyperbaric Medical Society (UHMS) keeps the most widely used list of accepted indications. It includes:

• air or gas embolism, and decompression sickness
• carbon monoxide poisoning
• gas gangrene and necrotising soft tissue infections
• crush injury and other acute traumatic loss of blood supply
• enhancement of healing in selected problem wounds
• delayed radiation injury to soft tissue and bone
• compromised skin grafts and flaps, and refractory osteomyelitis
• acute thermal burns and central retinal artery occlusion
• idiopathic sudden sensorineural hearing loss
• severe anaemia, intracranial abscess and avascular necrosis

Almost all of these are hospital or specialist problems, many of them emergencies. The UHMS describes scientifically supported treatments as usually delivered between 1.9 and 3.0 ATA, with most disorders needing daily treatment for several weeks.

UK funding is narrower than that list. According to its 2024 consultation guide, NHS England commissions HBOT from 8 centres for two indications: decompression illness and gas embolism. Its 2018 policy on carbon monoxide poisoning states that it will not routinely commission HBOT for that condition, even though it sits on the UHMS list. Expert bodies can read the same trials differently, which is worth remembering whenever a provider calls a use "proven".

If you think you have a diving injury or carbon monoxide poisoning, treat it as an emergency and call 999.

Which HBOT benefits are promising but not proven?

This is the band where most private HBOT sits, so the detail matters.

Late radiation tissue injury. A 2023 Cochrane review of 18 studies with 1,071 participants found that HBOT may improve or resolve late radiation tissue injury in selected patients, on low-certainty evidence. Pain from osteoradionecrosis improved slightly at 12 months, on moderate-certainty evidence. The review also found high-certainty evidence of a higher risk of reduced visual acuity. Our note on HBOT and cancer explains why this is a separate question from treating cancer.

Diabetic foot ulcers. A 2015 Cochrane review of 12 trials with 577 participants found better ulcer healing at six weeks, based on five trials with 205 participants. That benefit was not evident at one year, and the authors said trial flaws meant they were not confident in the results. NICE guideline NG19 (recommendation 1.5.12) says not to offer HBOT for diabetic foot ulcers unless as part of a clinical trial. Our non-healing wounds page covers wound care in more depth.

Sudden hearing loss. A Cochrane review of seven small, generally poor-quality trials with 392 participants found improved hearing in acute sudden sensorineural hearing loss, with one extra good outcome for roughly every five people treated. The authors urged caution and found no evidence of benefit for long-standing hearing loss or tinnitus. The UHMS protocol for this use is 2.0 to 2.5 ATA for 10 to 20 treatments, alongside steroids and specialist ear, nose and throat care.

Persistent symptoms after brain injury. A 2025 double-blind, sham-controlled trial randomised 49 adults, 47 of whom were analysed, to 40 sessions of HBOT at 1.5 ATA or a sham procedure over 12 weeks. Symptom scores improved by 10.6 points with HBOT against 3.6 with sham. The trial recruited about a third of its planned sample, and the UHMS still regards HBOT for brain injury as investigational. Our head injury page sets out what this does and does not show.

Long COVID. The randomised, double-blind HOT-LoCO trial found that ten sessions did not beat sham treatment on its primary outcomes. Other, uncontrolled studies have reported more encouraging results with longer schedules. Our summary of the HOT-LoCO trial explains the design.

What is hyperbaric oxygen therapy not shown to do?

Multiple sclerosis. A Cochrane review of nine trials with 504 participants found no consistent evidence of benefit and concluded that routine use is not justified. NICE guideline NG220 (recommendation 1.5.11) says: "Do not offer hyperbaric oxygen to treat fatigue in people with MS." Our multiple sclerosis evidence page goes through the trials.

Autism. NICE guideline CG170 (recommendation 1.6.4) lists hyperbaric oxygen therapy among interventions not to be used to manage autism in any context in children and young people.

General wellness, energy and anti-ageing. No UK guideline recommends HBOT for these. The advertising regulators' guidance on oxygen therapy states that the ASA and CAP have yet to see convincing evidence that hyperbaric oxygen used as an alternative therapy is efficacious in treating health conditions.

Very low-pressure sessions. The UHMS describes hyperbaric exposures below 1.5 ATA, often called mild hyperbaric oxygen, as unproven.

HBOT benefits at a glance

Use	Evidence grade	What the source says
Decompression illness and gas embolism	Established	On the UHMS list and routinely commissioned by NHS England
Carbon monoxide poisoning	Accepted, but not routinely funded in England	On the UHMS list; NHS England does not routinely commission it
Late radiation tissue injury	Promising, limited	Cochrane 2023: possible benefit, mostly low-certainty evidence
Diabetic foot ulcers	Mixed	Cochrane 2015: short-term gain not seen at one year; NICE NG19 advises against outside trials
Acute sudden hearing loss	Promising, limited	Cochrane: small, poor-quality trials, interpret cautiously
Persistent symptoms after brain injury	Early and investigational	One small sham-controlled trial, 40 sessions at 1.5 ATA, underpowered
Long COVID	Contested	HOT-LoCO: ten sessions no better than sham
Multiple sclerosis	Not supported	Cochrane: no consistent benefit; NICE NG220 advises against for MS fatigue
Autism	Not supported	NICE CG170: do not use
General wellness and anti-ageing	No supporting UK guidance	CAP has not seen convincing evidence

How should you weigh a benefit claim for yourself?

Start with the match between the research and the treatment on offer. HBOT Medics uses a single-person soft-shell chamber at 1.5 ATA. Most of the protocols the UHMS supports run at higher pressures, so their results cannot simply be assumed to apply here; the brain injury trial above is the main controlled study at 1.5 ATA. Our chamber page sets out what we can and cannot compare.

Then ask four questions of any benefit claim, including ours:

1. What kind of study? A sham-controlled trial tells you far more than a before-and-after series.
2. How many people, what pressure, how many sessions? A result from 40 sessions does not describe what one or ten will do.
3. Who screens you? A few conditions make HBOT unsafe. Read who HBOT is not suitable for before you book.
4. Does it sit alongside your usual care? HBOT should never replace treatment your own clinicians recommend.

If you want to understand the treatment itself first, read what HBOT is and what happens in a session. When you are ready, you can see available times. No referral needed. Medical consultation included with every Course.