Hyperbaric Oxygen Therapy for Long COVID: What the Research Shows

Hyperbaric oxygen therapy (HBOT) for long COVID rests mainly on one positive randomized controlled trial: according to Zilberman-Itskovich and colleagues (Scientific Reports, 2022), 40 sessions at 2.0 ATA with 100% oxygen improved cognition, energy, sleep, psychiatric symptoms and pain in 73 patients compared with a sham treatment. A 2025 Swedish trial of a shorter 10 session course found no benefit over placebo, so the research shows a promising but early signal for a treatment that is off label in the United States and almost always paid out of pocket.

If you have been navigating the fog, fatigue, and frustration of Long COVID, you already know how limited the treatment options feel. Most conventional approaches amount to “rest more, pace yourself, and wait.” For millions of people still struggling months or even years after their initial infection, that advice rings hollow.

Hyperbaric oxygen therapy, HBOT, has emerged as one of the more scientifically grounded interventions for Long COVID. Unlike many alternative treatments that rely on theory alone, HBOT for Long COVID now has randomized controlled trial data behind it. That does not promise any individual result, but it does mean the conversation has moved beyond speculation.

The sections below cover what the research actually shows, including the trial that did not find a benefit, how the mechanism is thought to work, what a treatment course looks like, what it costs, and how HBOT stacks up against other Long COVID interventions.

Does Hyperbaric Oxygen Therapy Help Long COVID?

Hyperbaric oxygen therapy improved brain fog, fatigue and related neurological symptoms in the strongest controlled Long COVID trial published so far, a 2022 sham-controlled study of 73 patients. The positive evidence comes mainly from one research group in Israel, and an independent Swedish trial using fewer sessions did not find a benefit. The honest summary is a real but unconfirmed signal that larger, independent trials still need to replicate.

Long COVID goes by several names in the research: post-COVID-19 condition (the World Health Organization term), post-COVID syndrome and PASC, short for post-acute sequelae of SARS-CoV-2 infection. HBOT is also called hyperbaric oxygenation or HBO2. Our long COVID condition overview covers the wider symptom picture, and the hyperbaric oxygen therapy treatment guide explains the therapy itself.

The Landmark Israeli RCT: Zilberman-Itskovich 2022

The study that put HBOT for Long COVID on the clinical map was published in Scientific Reports in 2022 by first author Shani Zilberman-Itskovich, senior author Dr. Shai Efrati and colleagues at the Sagol Center for Hyperbaric Medicine in Israel. This was not a case study or a retrospective chart review, it was a randomized, double-blind, sham-controlled trial, which is the gold standard in clinical research.

Here is what the study looked like:

• 73 patients with confirmed Long COVID symptoms lasting at least 3 months post-infection
• Patients randomized to either 40 sessions of HBOT at 2.0 ATA with 100% oxygen or a sham treatment (room air at 1.0 ATA)
• Sessions lasted 90 minutes each, five days per week
• Outcomes measured included cognitive function, psychiatric symptoms, pain, and quality of life

The results were clear on the measures the trial chose. Compared with the sham group, the HBOT group showed statistically significant improvements in:

• Global cognitive function, particularly attention and executive function
• Energy levels and fatigue severity
• Psychiatric symptoms, including depression and anxiety scores
• Pain interference with daily activities

Brain imaging (MRI perfusion studies) also showed measurable increases in cerebral blood flow in brain regions associated with the reported cognitive improvements. This is important because it provides an objective biomarker that corroborates the subjective symptom improvement.

What Did Later HBOT and Long COVID Studies Find?

Three later studies shape how the 2022 trial should be read: two from the same Israeli group that extend its findings, and an independent Swedish trial with a negative result.

Do the benefits of HBOT for Long COVID last?

Gains appear to last more than a year in the treated patients who were followed up. According to Hadanny and colleagues (Scientific Reports, 2024), 31 patients from the trial were reassessed an average of about 16 months after their final session. Gains in quality of life, sleep, psychiatric symptoms and pain were similar in size to those measured right after treatment. The follow-up had no sham group, so it shows durability rather than a fresh test of effect.

Does HBOT affect the heart in Long COVID?

A companion trial looked at the heart. According to Leitman and colleagues (Scientific Reports, 2023), 60 post-COVID patients were randomized to 40 HBOT or sham sessions, and in those with subtly reduced heart muscle strain on echocardiography, strain improved significantly after HBOT compared with sham. What that means for symptoms such as exercise intolerance is still unclear.

What did the Swedish HOT-LoCO trial find?

The HOT-LoCO trial found no benefit over placebo. According to Kjellberg and colleagues (BMJ Open, 2025), 80 previously healthy adults with Long COVID at a Swedish university hospital received either 10 HBOT sessions at 2.4 bar with 100% oxygen or a pressurized air placebo over six weeks. At 13 weeks both groups had improved, with no significant difference in physical functioning. The trials differ in dose (10 sessions versus 40) and main outcome (physical function versus cognition), so the Swedish result does not cancel the Israeli one, but the 40 session finding still needs independent replication.

For a longer walk through the individual outcome measures, see our breakdown of the HBOT long COVID clinical data.

How HBOT Works for Long COVID: The Mechanism

Long COVID is increasingly understood as a condition involving microvasculature damage, neuroinflammation, and tissue hypoxia, meaning the smallest blood vessels are impaired, the brain is inflamed, and tissues are not getting enough oxygen even though you are breathing normally.

HBOT works by having a patient breathe 100% oxygen inside a chamber pressurized above sea level, typically 2.0 atmospheres absolute (ATA) in Long COVID protocols. Researchers propose several mechanisms, mostly drawn from animal studies, imaging and other conditions, so treat them as the working explanation rather than settled fact.

1. Tissue Reoxygenation

Under pressure, oxygen dissolves directly into plasma at concentrations far above what hemoglobin alone can deliver. This hyperoxic state reaches tissues that damaged microvasculature cannot supply through normal circulation. For Long COVID patients with subtle perfusion deficits in the brain and other organs, this is the main rationale for treatment.

2. Neuroplasticity Stimulation

Studies of HBOT in brain injury suggest it can stimulate angiogenesis (new blood vessel formation) and neurogenesis (the formation of new neurons), along with new neural connections. Researchers describe the repeated swing between high and normal oxygen across sessions, sometimes called the hyperoxic-hypoxic paradox, as a trigger for growth factors, including VEGF and BDNF, that are linked to brain repair and neuroplasticity.

3. Anti-Inflammatory Effects

HBOT downregulates inflammatory cytokines and modulates immune function. Given that Long COVID involves persistent immune dysregulation, sometimes described as a “cytokine echo” of the original infection, this anti-inflammatory action may help reset the immune system toward normal function.

4. Mitochondrial Recovery

Emerging research suggests Long COVID impairs mitochondrial function, contributing to the profound fatigue patients experience. Laboratory work suggests HBOT may support mitochondrial repair and biogenesis, though this has not been shown directly in Long COVID trials.

The same oxygen-under-pressure mechanism underlies HBOT's established, FDA-cleared uses such as decompression sickness, carbon monoxide poisoning and diabetic foot wounds. Our overview of FDA-cleared indications for HBOT lists them.

What Symptoms Respond Best to HBOT?

Not all Long COVID symptoms are equally responsive to HBOT. Based on the available evidence and clinical experience, here is how different symptoms tend to respond:

The strongest evidence points toward neurological and cognitive symptoms as the primary beneficiaries of HBOT. This makes sense mechanistically, since the brain is particularly sensitive to oxygen deprivation and HBOT produces its largest measured changes in cerebral blood flow and oxygenation.

Brain fog is the symptom with the most direct trial support. If it is your main complaint, our guides to long COVID brain fog treatment options and the overlap with chronic fatigue syndrome (ME/CFS) put HBOT alongside the other approaches clinicians use.

The HBOT Protocol for Long COVID

The treatment protocol used in the Israeli RCT, and adopted by most clinics offering HBOT for Long COVID, follows this general structure:

• Pressure: 2.0 ATA (atmospheres absolute), equivalent to being approximately 33 feet underwater
• Oxygen: 100% medical-grade oxygen delivered via mask or hood
• Session duration: 90 minutes of pressurized treatment (plus approximately 15 minutes for compression and decompression)
• Frequency: 5 sessions per week (Monday through Friday)
• Total sessions: 40 sessions minimum; some protocols extend to 60 sessions for more severe cases
• Total treatment time: 8-12 weeks

What happens during an HBOT session?

1. A physician first screens your history, ears and lungs for contraindications.
2. You enter a multiplace chamber, a room where several patients breathe oxygen by mask or hood, or a monoplace chamber, a clear tube for one person.
3. During compression you equalize your ears, as on a descending flight.
4. At pressure you rest while breathing oxygen, usually with short air breaks to lower the risk of oxygen toxicity.
5. After slow decompression, most people return to normal activity the same day.

See mild HBOT versus clinical HBOT for the difference in dose, and the Efrati versus Harch protocol comparison for the two best known neurological schedules.

Is HBOT FDA Approved for Long COVID?

No. The US Food and Drug Administration (FDA) clears hyperbaric chambers for a defined list of conditions that largely mirrors the indications recognized by the Undersea and Hyperbaric Medical Society (UHMS), such as decompression sickness, carbon monoxide poisoning, non-healing diabetic wounds and delayed radiation injury. Long COVID is not on that list.

Using HBOT for Long COVID is therefore off label, which is legal when a licensed physician prescribes and supervises it. That is why insurers generally decline to pay, and the FDA has warned consumers about clinics that market HBOT for unapproved uses with claims beyond the evidence. The CDC and WHO do not list HBOT among recommended Long COVID treatments, while the NIH funds treatment research through its RECOVER initiative and further HBOT trials are registered on ClinicalTrials.gov.

Side Effects, Risks and Who Should Not Have HBOT

HBOT has a well characterized safety profile when run by trained staff. The most common side effects are ear and sinus barotrauma, temporary nearsightedness and tiredness after sessions; rarer risks include oxygen toxicity seizures, lung barotrauma and fire in the oxygen-rich chamber. In the HOT-LoCO trial, cough and chest discomfort were the most frequent complaints, at similar rates with HBOT and placebo.

Contraindications and cautions include:

• An untreated pneumothorax (collapsed lung), the main absolute contraindication.
• Past or current treatment with certain chemotherapy drugs, such as bleomycin.
• Poorly controlled seizures, severe lung disease, or ear and sinus problems that prevent equalizing.
• Severe claustrophobia or pregnancy, which need a specific discussion with the physician.

Our guide to hyperbaric chamber side effects covers each risk in more detail.

Cost Analysis: What HBOT for Long COVID Actually Costs

HBOT is a significant financial investment, especially since insurance typically does not cover it for Long COVID. Here is a realistic cost breakdown:

• Per-session cost: $150-$350 per session at most freestanding clinics
• 40-session course: $6,000-$14,000
• 60-session course: $9,000-$21,000
• Initial evaluation: $150-$500 (physician consultation, sometimes including imaging)
• Follow-up assessments: $100-$300 per visit

Some clinics offer package pricing that reduces the per-session cost by 10-20% when you commit to a full treatment course upfront. A few clinics also offer financing options or membership plans.

The total out-of-pocket cost for a typical 40-session protocol, including evaluations, ranges from $7,000 to $15,000.

Why does the price of HBOT for Long COVID vary so much?

Price depends on the setting, the chamber type and what the package includes. Some programs bundle cognitive testing, imaging and physician follow-up while others quote chamber time alone, so compare the full course. Our HBOT cost breakdown and HBOT cost by state show how prices differ.

HBOT vs. Other Long COVID Treatments

How does HBOT compare to other interventions being used for Long COVID? Here is an honest comparison:

HBOT has the strongest clinical trial evidence of any intervention on this list, but it is also by far the most expensive and time-intensive. For many patients, a practical approach involves starting with lower-cost interventions like pacing and LDN, and considering HBOT if cognitive and fatigue symptoms remain debilitating.

That evidence lead is narrower than it looks, since HBOT's positive data come from one research group. Low-dose naltrexone has only small studies behind it, and NAD+ IV therapy has almost no Long COVID trial data. Our Long COVID treatment overview covers these and other options.

Who Is a Good Candidate for HBOT?

Based on the research and clinical experience, the patients who most closely match those helped in the trials tend to be:

• Patients with prominent cognitive symptoms (brain fog, word-finding difficulty, memory problems)
• Those with persistent fatigue that has not responded to rest, pacing, and basic interventions
• Patients who are at least 3 months post-acute infection (to distinguish from normal recovery)
• People who can commit to the time and financial investment of a full treatment course
• Those without contraindications to HBOT (untreated pneumothorax, certain seizure disorders, active middle ear infections)

HBOT is probably not the best first-line choice for patients whose primary symptoms are autonomic (POTS, heart rate variability issues) or primarily respiratory, as the evidence for these specific symptoms is much weaker. For them, POTS treatment approaches are a more natural starting point.

Who Provides HBOT for Long COVID?

HBOT for Long COVID should be prescribed and supervised by a physician trained in undersea and hyperbaric medicine, a recognized US board subspecialty. Sessions are typically run by certified hyperbaric technologists (CHTs) or hyperbaric nurses. Hospital units may hold UHMS accreditation, while many Long COVID programs run in freestanding clinics, sometimes alongside neurologists, physiatrists or a post-COVID clinic team. Your primary care physician can help decide whether a referral makes sense.

How to Find an HBOT Clinic for Long COVID

Start with clinics that offer medical-grade chambers at 2.0 ATA with 100% oxygen and physician oversight. Regenerated.com lists HBOT clinics across the US by state and city. Listing order is not paid ranking, Featured slots are labeled and capped, Verified means the clinic completed our credential checks rather than paying, and the directory is free for patients. Inclusion is not an endorsement, so ask each clinic:

1. Which pressure, oxygen percentage and session length do you use?
2. Who is the supervising physician, and are they trained in hyperbaric medicine?
3. Is the facility UHMS accredited, and what is the emergency plan?
4. Which baseline and follow-up tests are included?
5. What is the full price of a 40 session course, and the refund policy if you stop?

Our guide to Featured, Verified and organic listings explains the directory labels.

Frequently Asked Questions

How quickly do Long COVID patients notice improvement with HBOT?

Improvement, when it comes, usually builds over several weeks rather than days. The Israeli trial measured outcomes one to three weeks after the full 40-session course, so it does not pin down exactly when change begins. Some patients report subtle energy improvements partway through, but the cognitive gains in the research followed eight weeks of consistent treatment, which is why clinicians recommend completing the full protocol before judging the result.

Can I use a home hyperbaric chamber for Long COVID?

Home “mild” hyperbaric chambers (1.3 ATA, ambient air) are not equivalent to the medical-grade treatment studied in the RCT (2.0 ATA, 100% oxygen). While some patients report anecdotal benefits from mild HBOT, there is no controlled evidence supporting home chambers for Long COVID. The oxygen delivery at 1.3 ATA with ambient air is dramatically lower than at 2.0 ATA with pure oxygen.

Is HBOT for Long COVID covered by insurance?

In the vast majority of cases, no. Insurance typically covers HBOT only for FDA-cleared indications such as decompression sickness, carbon monoxide poisoning, non-healing diabetic wounds, and radiation injury. Long COVID is not currently an FDA-cleared indication for HBOT, so treatment is almost always out-of-pocket. Patients can ask their insurer about an appeal backed by their physician, but approvals for this use are uncommon.

Are there any risks or side effects of HBOT for Long COVID patients?

HBOT is generally considered safe when administered in a properly supervised clinical setting. The most common side effects are ear and sinus pressure (barotrauma), temporary myopia (nearsightedness), and mild fatigue after sessions. Serious complications like oxygen toxicity seizures are extremely rare at the pressures used for Long COVID treatment (roughly 1 in 10,000 sessions). Some Long COVID patients report a temporary increase in fatigue during the first week of treatment before improvements begin.

How many HBOT sessions are needed for Long COVID?

The positive Long COVID trial used 40 sessions, given five days a week for about eight weeks at 2.0 ATA with 100% oxygen for 90 minutes each. Some clinics extend to 60 sessions for more severe cases, but no published trial has compared 40 sessions with 60. The Swedish HOT-LoCO trial found that 10 sessions did no better than placebo, so a short course has the least support in the research.

How do I find a hyperbaric clinic that treats Long COVID?

Look for a clinic with a medical-grade chamber, physician supervision and a protocol close to 2.0 ATA with 100% oxygen. The Regenerated.com HBOT directory lists clinics by state and city, its listing order is not paid ranking, and it is free to use. Ask each clinic about its supervising physician, UHMS accreditation, included testing and the full price of a course before you commit.

Related Reading

This article is part of our thorough guide to hyperbaric oxygen therapy. For a complete overview of how HBOT works, its applications, and what to expect during treatment, see our pillar article: Hyperbaric Oxygen Therapy: The Complete Guide.

For the wider picture, the Long COVID treatment guide compares the main approaches, and our summary of HBOT research tracks trials across conditions.