Hyperbaric oxygen shows promise for long COVID—at a cost

A hyperbaric oxygen therapy patient in Santa Fe says eight weeks of treatment helped restore normal neurocognitive test scores and let him return to driving and work. But clinical results are mixed, safety depends heavily on patient selection and trained deliv

M. Martinez had been living with long COVID for 18 months when he was referred to emergency medicine specialist Craig Lindsey’s hyperbaric center in Santa Fe, N.M.

The 49-year-old court professional—his first name withheld for privacy—had become so cognitively impaired that he could no longer work full-time or drive. He feared he might be forced to move into a memory care facility.

After eight weeks of hyperbaric oxygen therapy, or HBOT, two thirds of his neurocognitive test scores returned to the normal range, and he resumed working and driving.

Stories like Martinez’s are fueling interest in HBOT as a potential treatment for long COVID. a broad constellation of symptoms that includes brain fog and debilitating fatigue and affects millions of people worldwide. For now, there is no clear remedy. HBOT. which involves breathing pure oxygen under elevated pressure in a specialized chamber. is already established for several conditions—including decompression sickness from diving (the bends). carbon monoxide poisoning. and diabetic wounds. The question is whether it can help long COVID, and for whom.

Several biologically plausible mechanisms have been proposed, though none have been proven. Some people with long COVID appear to have difficulty extracting oxygen at the tissue level. possibly linked to thickened membranes in capillaries. Proponents argue HBOT may compensate by forcing more oxygen to dissolve in the blood.

Long COVID has also been linked with blood clotting, chronic inflammation, and malfunctioning mitochondria, the tiny engines that power cells. Supporters of HBOT say it may reduce blood vessel lining problems that trigger clotting. stimulate new blood vessel growth. tamp down inflammatory molecules called cytokines. and help mitochondria function better. HBOT has also been proposed to trigger the release of growth factors such as brain-derived neurotrophic factor. potentially helping repair neurons in long COVID patients with neuroinflammation.

The clinical evidence, however, is promising but inconsistent. A placebo-controlled phase 2 randomized trial of HBOT involving 73 long COVID patients at Shamir Medical Center in Israel found lasting improvements in cognition. energy. and sleep. Participants underwent daily sessions for 40 days over the course of two months. and in a follow-up study. the benefits lasted for at least a year.

But a subsequent Swedish trial of 80 subjects showed no advantage over placebo treatment. That protocol used only 10 sessions over six weeks.

“These treatments are really meant to be a Monday-through-Friday daily session,” Lindsey says, who was not involved in either study. “That’s where you get the benefit.”

Long COVID could arise from a wide range of underlying mechanisms. from viral persistence to immune dysregulation to vascular damage. and different people may “need vastly different treatments. ” says David Putrino. a professor of rehabilitation and human performance at the Icahn School of Medicine at Mount Sinai in New York City. who was not involved in the trials. HBOT, Putrino suggests through his comments, may be most appropriate for long COVID patients with vascular dysfunction or neuroinflammation.

Monica Verduzco-Gutierrez, who directs the multidisciplinary long COVID clinic at UT Health San Antonio, says “more studies are needed to figure out which [type of patient] will have the most benefit at what dosage.”

Safety is another reason results vary. While HBOT appears acceptably safe in controlled trials. Mark Faghy. a professor of clinical exercise physiology at Loughborough University in England. says it “should not be considered risk‑free.” A study of long COVID patients in the Netherlands found that while 56 to 63 percent reported meaningful quality-of-life improvements after HBOT. 13 to 19 percent saw their mental or physical health deteriorate.

People with postexertional malaise—when symptoms worsen after even minor physical or mental exertion—may be at higher risk for adverse effects. Faghy and Putrino point out. The treatment requires patients to be enclosed in a high‑pressure chamber. where they must breathe against that pressure. for 90 minutes a day. Putrino warns that “If your patients are not carefully selected. you can cause more harm than good by exerting them to that degree.”.

HBOT can also lead to tissue damage caused by pressure differences. and it poses a fire risk if not delivered by clinicians specifically trained in hyperbaric medicine. Hyperbaric chambers at unregulated “medical spas” are often run at pressures too low to be effective. and Lindsey warns that these facilities are staffed by people who “are not certified. ” making them both dangerous and ineffective.

There’s a parallel barrier: even if a therapy works for some patients, it still has to be recognized, reimbursed, and scaled.

Neither the U.S. Food and Drug Administration nor the Undersea and Hyperbaric Medical Society (UHMS). which accredits hyperbaric oxygen facilities. recognizes long COVID as an approved use for HBOT. The American Academy of Physical Medicine and Rehabilitation lists HBOT as an emerging therapy for long COVID.

In practice, funding and coverage are major obstacles. Lindell Weaver, a hyperbaric medicine specialist who has led phase 2 trials testing HBOT for traumatic brain injury, says U.S. insurers and Medicare are unlikely to cover HBOT for long COVID and brain injury without large. phase 3 trials run under FDA rules. “At the moment, no one is funding such trials,” Weaver says.

Hospitals bill roughly $5,000 per session, and a full 40-session course runs to $200,000. Faghy argues that this “creates significant equity concerns, as access is largely limited to people who can afford to self-fund treatment.”

Logistics compound the problem. Putrino says, “These are big devices that take up a lot of space.” In the U.S., Lindsey says there are only about 1,000 hospital-based hyperbaric facilities—nowhere near enough to serve the millions of people living with long COVID.

Sandra Wainwright. a hyperbaric physician in the Yale New Haven Health System and incoming president of UHMS. plans to form a committee to systematically review the evidence for the therapy’s new brain-related indications. including long COVID. She is optimistic that UHMS may act sooner than the FDA. but even with UHMS endorsement. she says widespread insurance coverage could be five to 10 years away.

For now, Verduzco-Gutierrez says the therapy will probably remain a supplementary option for “those who have the financial resources for it.”

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