Benefits of hyperbaric oxygen therapy: the 13 uses the FDA has cleared, and what the trials say about everything else

A hyperbaric chamber is the one recovery device on this site with a real medical history. The United States Navy has used it for decompression sickness since the 1930s, every major hospital has one for carbon monoxide poisoning and wounds that will not heal, and the Undersea and Hyperbaric Medical Society publishes a list of indications that an insurer will pay for. The home version is sold on the strength of that history for uses the history does not cover. This page separates the two, claim by claim, with the trial beside each.

What does a hyperbaric chamber do?

Oxygen reaches your tissues two ways. Almost all of it rides on hemoglobin, which is about 97% saturated when you breathe air at sea level and cannot be made much fuller. The rest dissolves in the plasma, and dissolved oxygen follows pressure: raise the partial pressure of oxygen in your lungs and more of it dissolves, with no ceiling.

That is the whole mechanism. The inspired oxygen pressure is the fraction of oxygen in what you breathe multiplied by the total pressure minus the 47 mmHg of water vapor your airway adds. Dissolved oxygen is about 0.0031 mL per deciliter of blood per mmHg of arterial oxygen pressure. Run those two numbers for the protocols people are actually sold:

The figures are computed from the alveolar gas equation with normal carbon dioxide, not measured in anyone; the point is the ratio. Resting tissue takes about 5 mL of oxygen from each deciliter of blood that passes, so at 2 atmospheres on pure oxygen the plasma alone can carry most of what tissue needs, which is why a hospital chamber keeps a crushed limb or a carbon monoxide victim’s brain alive while the blood or the hemoglobin recovers. A soft chamber on air adds about a seventh of that, and a 30% mask at 1.3 atmospheres is about what you would get from a 37% mask at sea level, lying on the couch. None of that is an argument about whether it helps; it is an argument about whether the home device and the clinical trials are the same intervention, and they are not. The portable chamber guide goes further into what 1.3 atmospheres is and is not.

The 13 uses the FDA has cleared

Chambers are Class II medical devices cleared through the 510(k) route, under product code CBF. The FDA’s consumer update, “Hyperbaric Oxygen Therapy: Get the Facts”, lists the disorders chambers have been cleared for as of July 2021; the live page was returning an error when we checked on 31 October 2026, so the list below is the text as republished by the Undersea and Hyperbaric Medical Society and others:

1. Air and gas bubbles in blood vessels
2. Anemia, when severe and blood transfusion cannot be used
3. Burns, severe and large, treated at a specialized burn center
4. Carbon monoxide poisoning
5. Crush injury
6. Decompression sickness
7. Gas gangrene
8. Hearing loss, complete, sudden and without a known cause
9. Infection of the skin and bone, severe
10. Radiation injury
11. Skin graft or flap at risk of tissue death
12. Vision loss, sudden and painless in one eye, from a blocked blood vessel
13. Wounds that will not heal, such as diabetic foot ulcers

The same FDA text says chambers “are not proven to cure cancer, Lyme disease, autism or Alzheimer’s disease” and that the agency “has not cleared or authorized the use of any HBOT device to treat COVID-19”. It does not mention concussion, long COVID, aging, athletic recovery or sleep, because nothing beyond the 13 is cleared, and it says it is aware of centers promoting chambers for uses it has not cleared.

The UHMS’s own list, the one insurers use, runs to 15 numbered indications in its current edition: the 13 above with the sub-items split out, plus intracranial abscess, cyanide poisoning alongside carbon monoxide, and avascular necrosis of bone, which its board added in June 2022. Medicare’s national coverage determination covers 15 conditions of the same kind and explicitly refuses 22 others, including chronic brain syndrome, multiple sclerosis, arthritis and thermal burns. The cost guide has what a covered session pays.

Notice what the cleared list is: every entry is an emergency, an infection, a dying graft or a wound, treated in a hospital at 2 to 3 atmospheres on 100% oxygen, for a defined number of sessions. Nothing on it is a reason to own a chamber.

What the trials found for the uses that sell home chambers

Muscle recovery and soreness

This is the best-studied wellness claim and the clearest negative on the page. The 2005 Cochrane review pooled nine trials and 219 participants on HBOT for delayed-onset muscle soreness and found pain was higher with HBOT at 48 hours, by 0.88 points on a 0 to 10 scale (95% CI 0.09 to 1.67), and at 72 hours, with no difference in longer-term pain, swelling or strength. Its conclusion: some evidence that HBOT may increase interim pain.

The individual trials agree. Mekjavic, 24 men, 2.5 atmospheres for 60 minutes daily for a week, double-blind: strength fell from 25.1 to 12.0 kp in the HBOT group and 24.6 to 12.5 with placebo, and recovered on the same curve. Babul, 16 women, 2.0 atmospheres on 100% oxygen for 60 minutes, four sessions, against 1.2 atmospheres on air: no difference in pain, strength, creatine kinase or MRI. Germain, 16 students, 2.5 atmospheres for 100 minutes, five sessions: soreness and creatine kinase no different. Staples, 66 untrained men at 2.0 atmospheres, is the one with a signal: eccentric quadriceps torque recovered faster in the group that got five sessions, with no difference in pain.

Two more recent summaries. Huang’s 2021 meta-analysis of ten studies and 166 participants found no effect of post-exercise HBOT on creatine kinase (mean difference −14.8 U/L, 95% CI −106.2 to 76.6), lactate dehydrogenase or lactate, and concluded it does not improve performance or recovery. Gušić’s 2024 trial, 20 elite youth footballers, one 60-minute session at 2.2 atmospheres on 100% oxygen after a match against a 1-atmosphere placebo, found no difference in creatine kinase (P = 0.66), lactate dehydrogenase, myoglobin, jumps or sprints; only a wellness questionnaire differed, at one hour.

Every one of these was a 2 to 2.5 atmosphere clinical protocol. There is no trial of a 1.3 atmosphere home chamber for recovery at all. The honest reading is that the strongest version of the intervention did not speed recovery, and the home version is untested. A cold plunge has better soreness evidence than this, and a massage gun costs a hundredth as much.

Concussion and mild traumatic brain injury

The Department of Defense ran the largest trials, and their design is the thing to understand. Because earlier studies had seen improvement in both treated and control groups, the DoD trials used pressurized room air at 1.2 or 1.3 atmospheres as the sham, so that the chamber experience was identical and only the oxygen dose differed.

• Wolf, 2012: 50 service members, 30 sessions, 2.4 atmospheres on 100% oxygen against 1.3 atmospheres on room air. Both groups improved within themselves (P = 0.001); no difference between them on cognitive testing (P = 0.35) or post-traumatic stress symptoms (P = 0.84).
• HOPPS, Miller, 2015: 72 service members, 40 sessions at 1.5 atmospheres on oxygen, against 40 sessions of 1.2-atmosphere air, against routine care alone. A two-point improvement on the post-concussion questionnaire in 52% of the oxygen group, 33% of the sham group and 25% of routine care (P = .24 across arms); oxygen against sham, P = .70. The authors attributed the improvement in both chamber groups to nonspecific, placebo-type effects.
• BIMA, Weaver, 2018: 71 service members, 40 sessions at 1.5 atmospheres on oxygen or 1.2 on air. Here the oxygen group did better on the neurobehavioral symptom inventory at 13 weeks (−3.6 against +3.9, P = 0.03), and more so in those with PTSD, but the authors report the changes did not persist beyond six months.
• Cifu, 2014: 60 Marines, all at 2.0 atmospheres, breathing 10.5%, 75% or 100% oxygen so that the oxygen dose varied and the pressure did not: no difference at three months.

Against these sits Boussi-Gross, 2013, 56 Israeli civilians one to five years after a mild TBI, 40 sessions at 1.5 atmospheres on oxygen, in a crossover design with no sham: information-processing speed rose from 85.1 to 95.0 and memory from 82.4 to 96.5 on a standardized scale, with no change during the untreated period. Its evaluators were blinded; its patients, lying in a chamber or not, were not.

Proponents argue that pressurized air is not an inert sham, and that the DoD trials are therefore dose comparisons in which both arms worked. That is a real argument, and it cuts both ways for a home buyer: if 1.2 atmospheres of air does what 1.5 atmospheres of oxygen does, the cheap soft chamber is the right one; if it does not, the home chamber delivered the dose the trials used as placebo. What nobody has run is the trial that settles it, with an unpressurized sham.

Aging, telomeres and “reversing” cell age

One study carries this claim. Hachmo and colleagues, 2020, in Aging: 35 adults aged 64 and over, 60 daily sessions at 2 atmospheres on 100% oxygen for 90 minutes with air breaks, no control group. In the 25 with telomere data, B-cell telomere length was 37.6% longer after the course, with a standard deviation of 52.7% (P = 0.007); T-helper cells 29.3%, natural killer cells 22.2% (P = 0.06). Senescent T-helper cells fell 37.3% (P < 0.0001). The authors list the limitations themselves: small sample, no control, duration of the effect unknown, telomerase not measured. Three of them were employees of, and one a shareholder in, AVIV Scientific, which sells the protocol. Telomere length in a blood sample is a marker; nobody has measured whether any of this changes a health outcome, and the protocol was 60 hospital-grade sessions, not a soft bag in a spare room.

Cognition in healthy older adults

Hadanny, 2020, same group, same protocol: 63 healthy adults with a mean age of 69.7 randomized to 60 sessions or to no intervention, not a sham. The global cognitive score rose from 105.4 to 110.6 in the treated group against 102.2 to 103.0 in controls (P = 0.0017), with attention and processing speed the largest effects. Two findings from the safety data belong on this page: 4 of 30 treated participants had middle-ear barotrauma, and 62% had a change in visual acuity against 37% of controls. Without a sham group, the attention and effort of sixty hospital visits is in the treated arm’s score and not the control’s.

Long COVID

Zilberman-Itskovich, 2022, the one double-blind, sham-controlled trial on this page from the Israeli group: 73 people with post-COVID symptoms, 40 sessions at 2 atmospheres on 100% oxygen against a sham at 1.03 atmospheres on air. Effect sizes of about 0.5 on global cognition, attention and energy, 0.64 on psychiatric symptoms and 0.74 on pain interference, with side effects no more common than sham (35% against 39%). It is a positive, properly controlled trial of a 2-atmosphere protocol in a specific illness. It is also the one the FDA statement above refers to when it says no chamber is cleared for COVID-19.

PTSD, stroke and fibromyalgia

Same group, same protocol, no sham in any of them. Doenyas-Barak, 2022: 35 veterans with treatment-resistant PTSD, 60 sessions against no intervention; the clinician-rated PTSD score fell 18.1 points (95% CI −25.4 to −10.8) against a 2-point rise in controls, with 7 cases of mild ear barotrauma. Efrati, 2013: 74 stroke patients six months to three years out, 40 sessions, crossover; stroke scale and daily-living scores improved during treatment and not during the waiting period. Efrati, 2015: 60 women with fibromyalgia, 40 sessions, crossover; tender-point count and pain threshold improved. All three are signals worth a sham-controlled trial; none is one.

Autism, and the one time 1.3 atmospheres was the treatment

The autism literature matters here because it is the only place 1.3 atmospheres on near-air was tested as the active arm rather than the sham. Rossignol, 2009: 62 children, 40 sessions at 1.3 atmospheres on 24% oxygen against 1.03 atmospheres on 21%; physicians rated 30% “much improved” against 8% (P = 0.047), with parents in the chamber and the blinding questioned since. The follow-up by Granpeesheh, 2011, 16 children at the same dose in a multiple-baseline design, found no consistent effects, and the 2016 Cochrane review found one qualifying trial of 60 children with no improvement and more ear barotrauma. In cerebral palsy, Collet’s 2001 Lancet trial of 111 children found 1.75 atmospheres on oxygen and 1.3 atmospheres on air produced the same 3% gain in motor function, with ear problems in 27 of the oxygen children against 15 of the air children (P = 0.004).

Pros and cons of a hyperbaric chamber, on this evidence

The case for a clinical course: for the 13 cleared conditions it is standard care, the long-COVID trial is a real controlled positive, and the concussion, PTSD and cognition studies are signals a clinician can weigh against the alternatives for a specific patient. The case against buying one for wellness: the one wellness use with a Cochrane review, muscle recovery, came out negative at 2 to 2.5 atmospheres; the concussion trials could not separate oxygen from pressurized air; the aging study has no control group and a commercial conflict; and no trial has tested the 1.3-atmosphere device that is actually for sale for any of these.

Side effects, and who must not

The numbers are from Heyboer’s 2017 review in Advances in Wound Care and the UHMS’s own side-effects chapter, from clinical chambers at clinical pressures:

• Middle-ear barotrauma is the common one: 43% of patients in Heyboer’s own center’s series, 84% of those mild and none a ruptured eardrum; other series range from 2% to 84% depending on how hard anyone looked. It is a squeeze on descent, it hurts, and you clear it the way a diver does.
• Oxygen-toxicity seizures depend on pressure. In Heyboer’s 23,328-treatment review, 1 in 2,121 overall, none in 16,430 treatments at 2.0 atmospheres, 1 in 669 at 2.4 to 2.5 and 1 in 197 at 2.8. Hadanny’s 62,614-session series found 1 in 8,945 seizures of any kind. A home chamber at 1.3 atmospheres on air is far below the dose that produces these.
• Nearsightedness shifts about 0.25 diopters a week at 2 atmospheres or more and reverses over three to six weeks, occasionally longer; cataract has been reported after very long courses.
• Confinement anxiety in about 2% of patients; nosebleeds about 1 in 10,000 treatments; low blood sugar in diabetics in about 1 to 1.5% of treatments.
• The absolute contraindication is an untreated collapsed lung, which expands on the way back down. Relative ones: a cold or blocked sinuses, air-trapping lung disease or a previous spontaneous pneumothorax, heart failure with a low ejection fraction, epilepsy, fever, and several chemotherapy drugs, bleomycin above all. Implanted devices need the maker’s pressure rating. Ask the clinic; a home seller will not.

What we have not measured

Nothing on this page is ours. Every effect size is a trial’s, every rate a hospital’s, and we have not sat in a chamber of either kind.

The measurements a buyer would want, and that no seller publishes, are all cheap. A calibrated pressure gauge on a soft chamber’s port through a session, because 1.3 atmospheres is the valve’s setting, not necessarily the number at the mattress. A handheld oxygen analyzer, the $300 kind divers use, at the mask outlet and inside the bag over an hour, because the sellers’ “about 30%” is the number that decides whether the device is the 1.3× or the 1.9× row in the table above, and because the in-bag reading is the fire question. A fingertip pulse oximeter, which will read 98% before, during and after, and so tells you only that hemoglobin was already full, which is the whole argument. And a sound meter on the compressor, since the chamber you stop using is the one that helps nobody. One chamber, one afternoon, n=1. If a maker lends one, this page gets a table.

Where that leaves a buyer

For a cleared condition, this is hospital medicine with a referral and, usually, coverage. For long COVID, the one controlled positive trial used a 2-atmosphere clinic protocol, and the clinics that run it are where that evidence applies. For concussion, PTSD and the aging and cognition claims, the trials are small, mostly unshammed and often run by the sellers, and every one used a dose a home chamber cannot reach. For muscle recovery, the trials say no, at any pressure.

If you still want a chamber at home, the home chamber guide says which ones are legal to buy and what they cost installed, the portable chamber guide explains soft against hard shells and what 1.3 atmospheres is, and our how we test page says what every figure here is and is not.