Hyperbaric Oxygen Therapy for Long COVID: Can HBOT Support Recovery?

Long after a COVID-19 infection has cleared, plenty of people are left with a version of themselves that tires more easily, thinks less clearly, and feels off in ways that are hard to pin down. When standard treatments haven't closed that gap, some patients start asking their care team about hyperbaric oxygen therapy for long COVID: sitting inside a sealed chamber and breathing concentrated oxygen under pressure. Interest in the approach has grown quickly, but the underlying science hasn't caught up evenly - a cluster of smaller trials points toward genuine benefit, while the single best-designed, independently run study to date landed on essentially no difference from a placebo. This piece lays out what long COVID looks like clinically, why raising oxygen pressure is thought to matter physiologically, and what happens when the favorable trial data is weighed directly against the disappointing.

Long COVID, Defined

Clinicians increasingly use "post-COVID condition" for what patients call long COVID: a pattern of symptoms that persists for months once the acute infection itself is long gone. Those affected typically describe relentless exhaustion, trouble focusing that's often shorthanded as brain fog, exercise that wipes them out far more than it used to, poor sleep, and aches without an obvious cause. One reason long COVID is so hard to manage is that its presentation overlaps heavily with other chronic illnesses and varies widely between patients - which is exactly why clinicians and researchers keep testing supportive interventions, hyperbaric oxygen among them.

How Hyperbaric Oxygen Therapy Works

Inside an HBOT chamber, a patient breathes close to pure oxygen while the surrounding air pressure climbs well past what's normal at sea level. That extra pressure forces far more oxygen to dissolve straight into blood plasma than lungs could ever pull in from ordinary room air - the theoretical basis for pushing more oxygen out to tissue that needs it.

Inside a Session

A typical session eases the patient in with a gradual rise in pressure and oxygen levels, holds steady at the target for a stretch, then brings pressure back down slowly. At Humanaut Health, trained clinical staff run every session as one piece of a broader recovery-oriented lineup, watching comfort and safety the entire way through.

Hyperbaric Oxygen Therapy for Long COVID: What Does the Research Show?

The data here doesn't point in one direction, and laying out the conflicting findings honestly matters more than cherry-picking the flattering ones.

The Case for Benefit

One sham-controlled randomized trial reported that a course of 40 HBOT sessions produced meaningful gains in overall cognition, attention, energy, sleep quality, and pain versus a fake ("sham") treatment among post-COVID patients (Zilberman-Itskovich et al., Scientific Reports, 2022). A later check-in on that same group of patients found the gains had mostly held up roughly a year out (Hadanny et al., Scientific Reports, 2024), and a narrower sub-study from the same cohort pointed to improved heart function after treatment (Leitman et al., Scientific Reports, 2023). A separate pooled analysis spanning seven studies and close to 200 participants also turned up consistent gains in memory, executive function, attention, and fatigue - though its authors flagged that small sample sizes and inconsistent methods limit what conclusions can be drawn (Undersea & Hyperbaric Medicine, 2025).

The Trial That Found Nothing

Set against that, the field's largest and most tightly controlled independent trial tells a very different story. Sweden's HOT-LoCO study - a randomized, sham-controlled, double-blind Phase II trial enrolling 80 patients - turned up no statistically meaningful gap between real HBOT and sham treatment on either primary measure it tracked, physical functioning and role limitations tied to physical health, after 13 weeks; both arms improved roughly in step regardless of which treatment they'd received (Kjellberg et al., BMJ Open, 2025). Its independence from the groups behind the positive findings, along with its tighter design, makes it a genuine counterweight to the more encouraging results above rather than a footnote to them.

What Real-World Data Adds

Outside the randomized-trial world, the picture gets messier rather than clearer. A 232-patient prospective registry found 56 to 63 percent of participants reporting a meaningful quality-of-life gain three months out, but with no comparison group built into the design (Scientific Reports, 2025). A small pilot program run in a community setting similarly noted improvements in fatigue and quality of life after a four-week course, while its own investigators pointed out that many participants struggled to keep up with attendance and called for a properly controlled follow-up (Gale et al., British Journal of Nursing, 2026). With no control arm in either study, the possibility that symptoms simply improved on their own can't be excluded.

Where Guidelines Stand

No FDA approval currently covers this use of the therapy for post-COVID condition, and no major medical society has put out a formal guideline endorsing it for this purpose. Tellingly, a systematic-review protocol published by researchers actively working in this space states outright that the efficacy and safety of HBOT for long COVID "remain unclear" (BMJ Open protocol, 2024) - a candid admission, from people with every incentive to be optimistic, that this remains an open research question rather than settled medical practice.

Where HBOT Fits Among Other Recovery Options

No single intervention has been shown to resolve long COVID outright, which is why many patients end up combining a few supportive approaches under a physician's guidance. EBO2 therapy - which filters and oxygenates blood outside the body - has also drawn research interest as a possible support for lingering post-COVID symptoms, a topic covered in more depth in our earlier piece on EBOO for long COVID. As with hyperbaric oxygen, the evidence behind these adjacent approaches is still developing and works best as part of a conversation with a qualified provider, not as a standalone fix.

Weighing the Risks

An interim safety readout from the HOT-LoCO trial turned up no serious adverse events tied to HBOT (Kjellberg et al., BMC Infectious Diseases, 2023), consistent with how the therapy is usually described in supervised clinical settings: generally well tolerated, not risk-free. Ear or sinus pressure discomfort (barotrauma), short-lived vision changes, and post-session fatigue turn up most often among reported effects. Clinicians typically steer people with an untreated pneumothorax, certain lung conditions, or specific ear and sinus issues away from HBOT altogether, which is exactly why a clinical screening beforehand isn't optional.

Setting Realistic Expectations

Given how split the evidence is, expectations matter. Some trial participants reported real, noticeable improvement; others - notably in the best-controlled independent study - saw nothing beyond what a placebo delivered. Individual response appears to swing widely from person to person, and the research so far offers no reliable way to predict who falls into which group. That uncertainty is exactly why HBOT is best treated as one component within a broader, individualized recovery plan rather than a guaranteed fix.

Frequently Asked Questions About HBOT for Long COVID

What is hyperbaric oxygen therapy (HBOT) and how might it relate to long COVID?

HBOT means breathing highly concentrated oxygen inside a pressurized chamber so more oxygen reaches tissue throughout the body. Researchers are testing whether that process eases specific long COVID symptoms like fatigue and cognitive trouble, though findings across studies still conflict.

Does hyperbaric oxygen therapy help with long COVID symptoms?

It depends on which study you look at. Several sham-controlled trials describe gains in cognition, fatigue, and quality of life, while the largest independent trial found no meaningful edge over placebo. Researchers themselves describe the evidence as encouraging but unresolved.

Is HBOT FDA-approved for treating long COVID?

No. There's no FDA approval covering this therapy for post-COVID condition, and no major medical guideline currently recommends using it for this purpose.

What symptoms of long COVID has HBOT been studied for?

Trials have mainly looked at fatigue, cognitive issues like memory and attention, disrupted sleep, pain, and - in a handful of smaller studies - cardiac and general quality-of-life measures.

How many HBOT sessions do studies on long covid typically use?

Protocols vary considerably: some trials run roughly 40 daily sessions, others use shorter courses closer to 10. There's no single agreed-upon session count specific to long COVID.

Is hbot for long covid safe?

Interim data from a large controlled trial found no serious adverse events linked to the therapy, and it's generally considered well tolerated under clinical supervision. That said, minor effects like ear discomfort do occur, and certain conditions rule it out entirely, so a pre-treatment clinical evaluation is essential.

What did the largest clinical trial find about hyperbaric oxygen therapy and long covid?

Sweden's HOT-LoCO trial - the largest independent, placebo-controlled study on the subject - found no statistically significant difference between real HBOT and sham treatment for physical functioning or role limitations after 13 weeks.

Who should avoid hyperbaric oxygen therapy?

People with an untreated pneumothorax, certain lung or ear conditions, or other specific contraindications are generally advised against HBOT. A qualified clinician should review individual health history before any hyperbaric session is scheduled.

Key Takeaways

• Long COVID brings persistent symptoms - fatigue, brain fog, reduced exercise tolerance - that can drag on for months after the initial infection.
• Some sham-controlled trials of this therapy report real gains for people with long COVID, especially in cognition and fatigue.
• The largest independent, placebo-controlled trial found no meaningful benefit over sham treatment, leaving the overall evidence genuinely mixed.
• No FDA approval or formal medical guideline currently supports this use of the therapy.
• Side effects tend to be mild, though specific health conditions rule the therapy out, making clinical evaluation essential.
• Anyone weighing this option should walk through the current evidence, and their own health history, with a qualified provider first.

Curious whether it's a fit for your recovery plan? Explore Humanaut Health's HBOT program as part of a broader, personalized approach to care.