Hyperbaric oxygen therapy (HBOT) is a medical treatment where you breathe pure oxygen inside a pressurized chamber, typically at two to three times normal atmospheric pressure. The increased pressure forces significantly more oxygen into your blood plasma than you could ever absorb by breathing normally. This supercharged oxygen delivery accelerates healing, fights certain infections, and treats conditions ranging from carbon monoxide poisoning to diabetic wounds.
How Pressurized Oxygen Works in Your Body
Under normal conditions, almost all the oxygen in your blood is carried by red blood cells. There’s a limit to how much they can hold. Hyperbaric therapy gets around that bottleneck by dissolving extra oxygen directly into your blood plasma, the liquid portion of your blood. The physics are straightforward: the higher the pressure, the more gas dissolves into a liquid. At 2.4 times normal atmospheric pressure (a common treatment setting), your arterial oxygen levels can reach about 1,824 mmHg, compared to roughly 157 mmHg when you’re breathing regular air at sea level. That’s more than a tenfold increase.
All that extra dissolved oxygen can reach tissues that damaged or blocked blood vessels might otherwise starve. This is why HBOT is particularly useful for wound healing, crush injuries, and tissue damaged by radiation therapy. Oxygen-rich plasma can seep into areas where red blood cells physically can’t go.
What Happens at the Cellular Level
Beyond simply flooding tissues with oxygen, HBOT triggers a cascade of biological responses. One of the more striking findings is that it mobilizes stem cells from your bone marrow. Research has shown that post-treatment levels of bone marrow stem cells consistently double compared to pre-treatment values. These mobilized stem cells have been shown in animal studies to form new blood vessels and speed up wound healing.
HBOT also appears to influence aging at the cellular level. A prospective trial found that after 60 sessions, telomere length (the protective caps on chromosomes that shorten with age) increased by over 20% across several types of immune cells, with B cells showing the largest gains at nearly 38%. At the same time, the number of senescent immune cells, essentially worn-out cells that contribute to inflammation and aging, dropped significantly. Senescent helper T cells decreased by about 37%, and senescent cytotoxic T cells dropped by roughly 11%. These are notable findings, though research in this area is still young and involved small study populations.
Conditions Covered by Insurance
Medicare and most insurers cover HBOT for a specific list of conditions. These are the diagnoses that have enough clinical evidence behind them to qualify:
- Carbon monoxide or cyanide poisoning
- Decompression sickness (the “bends” from diving)
- Gas embolism (dangerous air bubbles in the bloodstream)
- Gas gangrene and progressive necrotizing infections
- Crush injuries and reattachment of severed limbs
- Compromised skin grafts
- Chronic bone infections that haven’t responded to surgery and antibiotics
- Radiation damage to bone or soft tissue
- Acute blood flow problems in the arms or legs
- Diabetic foot wounds classified as Wagner grade III or higher, after standard wound care has failed
For diabetic wounds specifically, coverage requires that you’ve already tried and failed a standard course of wound therapy. The wound also needs to be severe enough to involve deep tissue. Mild diabetic ulcers won’t qualify.
Hard Chambers vs. Soft Chambers
Not all hyperbaric chambers deliver the same treatment. The distinction matters more than most people realize.
Hard-shell chambers are medical-grade, steel-enclosed units found in hospitals and dedicated clinics. They deliver 100% oxygen at pressures above 2.0 ATA and are FDA-approved for treating the conditions listed above. These are what doctors mean when they prescribe HBOT.
Soft-sided chambers are portable, inflatable units that seal with a zipper. They top out at around 1.3 ATA and typically deliver only about 24% oxygen, barely above the 21% in normal room air. At those settings, your blood oxygen reaches roughly 230 mmHg. That’s a modest bump from the normal 157 mmHg, but nowhere close to the 1,824 mmHg a hard chamber achieves at 2.4 ATA. Soft chambers are not FDA-approved as medical devices for hyperbaric therapy, with one narrow exception: helping climbers and divers with altitude sickness during transport to a real medical facility.
If you’re considering purchasing or renting a soft chamber for home use, understand that it delivers a fundamentally different treatment than what clinical research has studied. Most of the proven benefits of HBOT come from pressures and oxygen concentrations that soft chambers simply cannot reach.
What a Session Feels Like
A typical HBOT session lasts 90 minutes to two hours. In a monoplace chamber (designed for one person), you lie down inside a clear acrylic tube while the pressure gradually increases. In a multiplace chamber, several people sit together in a room-sized space, breathing oxygen through masks or hoods.
As the chamber pressurizes, you’ll feel fullness in your ears, similar to the sensation during airplane descent. You equalize the pressure the same way: swallowing, yawning, or gently blowing with your nose pinched. Treatment courses vary by condition. Wound healing protocols often involve 20 to 40 sessions, sometimes more, with daily treatments five days a week. Emergency conditions like carbon monoxide poisoning may require only a few sessions.
Risks and Side Effects
HBOT has one absolute contraindication: an untreated collapsed lung (pneumothorax). Pressurizing a chamber with a collapsed lung could be fatal. Trapped gas inside the eye from recent surgery is also considered a near-absolute contraindication because the pressure changes could cause vision loss.
The relative contraindications are a longer list, including COPD, asthma, uncontrolled seizure disorders, pregnancy, claustrophobia, certain chemotherapy drugs, active respiratory infections, and difficulty equalizing ear pressure. None of these automatically disqualify you, but they require careful evaluation.
The most common side effect is barotrauma to the ears or sinuses, essentially pressure-related pain from an inability to equalize properly. This is usually mild but can occasionally damage the eardrum. Oxygen toxicity is a rarer concern that can show up as seizures during treatment or, over many sessions, as lung irritation. People with insulin-dependent diabetes need monitoring because HBOT can cause blood sugar drops during treatment.
Vision changes are another temporary side effect. Some people develop mild nearsightedness over the course of a treatment series, which typically reverses within weeks to months after stopping therapy.
Off-Label and Unproven Uses
Beyond the approved indications, HBOT is marketed for a wide range of conditions: traumatic brain injury, autism, chronic fatigue, athletic recovery, anti-aging, and cognitive enhancement. The telomere and senescent cell research mentioned earlier has fueled particular interest in longevity applications. While some of these areas have promising preliminary data, none have the level of evidence that the approved conditions do, and insurance will not cover them.
Out-of-pocket costs for HBOT vary widely, from around $100 to $300 per session at independent clinics, with a full course of 40 sessions potentially running $4,000 to $12,000. If you’re pursuing treatment for an off-label condition, that entire cost is yours. For approved conditions, Medicare and most private insurers cover the therapy, though you’ll still need a referral and documentation showing you meet the specific criteria for your diagnosis.