HBOT stands for hyperbaric oxygen therapy, a medical treatment where you breathe pure oxygen inside a pressurized chamber. The increased pressure, typically two to three times normal atmospheric pressure, forces significantly more oxygen into your blood than regular breathing ever could. It’s used to treat a specific set of conditions, from carbon monoxide poisoning to diabetic wounds that won’t heal.
How HBOT Works in Your Body
Under normal conditions, almost all the oxygen in your blood rides on hemoglobin, the protein inside red blood cells. There’s a limit to how much oxygen hemoglobin can carry, and for most healthy people, it’s already near capacity. HBOT gets around this bottleneck by dissolving oxygen directly into your blood plasma, the liquid portion of blood that hemoglobin floats in.
This works because of a basic physics principle: the higher the pressure around a gas, the more of it dissolves into liquid. At three times normal atmospheric pressure (called 3 ATA), the amount of oxygen dissolved in your plasma jumps to about 60 milliliters per liter. That’s enough oxygen to sustain basic tissue needs even without hemoglobin doing any work at all. This oxygen-rich plasma can reach areas where red blood cells struggle to go, like swollen or damaged tissue with compromised blood flow.
Conditions HBOT Is Approved to Treat
Medicare and most private insurers recognize a specific list of conditions for HBOT coverage. These fall into a few broad categories:
- Emergency poisoning and diving injuries: carbon monoxide poisoning, cyanide poisoning, decompression sickness (the bends), and air or gas bubbles in the bloodstream (gas embolism)
- Infections: gas gangrene, progressive flesh-destroying infections, and actinomycosis that hasn’t responded to antibiotics and surgery
- Wound healing and tissue damage: crush injuries, severed limbs being reattached, failing skin grafts, bone infections that won’t clear with standard treatment, and tissue damage from radiation therapy
- Diabetic foot wounds: covered when the wound is classified as severe (Wagner grade III or higher) and hasn’t improved with standard wound care
- Blood flow emergencies: sudden loss of blood flow to the limbs
Some of these, like carbon monoxide poisoning, require only one or two sessions. Others, like chronic diabetic wounds, may call for 40 or more treatments before results appear.
What a Treatment Session Looks Like
There are two types of chambers. A monoplace chamber is a clear acrylic tube designed for one person. You lie down, the chamber is sealed, and it fills with pure oxygen as pressure gradually increases. No mask or hood is needed because the entire chamber is pressurized with oxygen. These units are smaller, less expensive to operate, and don’t require staff inside the chamber.
A multiplace chamber is a larger room-sized unit that can treat several patients at once, with a technician or nurse inside. Patients breathe oxygen through a mask or hood while the chamber itself is pressurized with regular air. Multiplace chambers are better suited for critically ill patients because medical staff can be right there, using standard monitoring equipment and providing hands-on care. In a monoplace chamber, IV lines have to pass through the chamber wall to external pumps, and ventilators are more limited.
A typical course of treatment varies widely by condition. People with acute poisoning may need just one or two sessions. Chronic conditions like non-healing wounds or radiation tissue damage often require 20 to 40 sessions, sometimes more. Your treatment plan will specify the pressure level, session length, and frequency.
Risks and Side Effects
The only absolute reason HBOT cannot be performed is an untreated collapsed lung (pneumothorax), because the pressure changes could make it life-threatening. Having gas inside the eye, such as after certain eye surgeries, is also considered a contraindication for anything short of an emergency, since expanding gas could cause vision loss.
The most common side effect is ear and sinus pain from pressure changes, similar to what you feel during airplane descent but more intense. People who have trouble equalizing pressure due to prior ear surgery, radiation to the head, or even a head cold are at higher risk for eardrum injury. Most facilities teach you equalization techniques beforehand, and sessions can be paused if you’re having trouble.
Oxygen toxicity is a rarer but more serious concern. Breathing pure oxygen at high pressure for extended periods can, in uncommon cases, trigger seizures or lung irritation. Certain factors raise this risk: high fever, a history of epilepsy, or taking specific medications that interfere with the body’s natural defenses against oxygen-related cell damage. Treatment protocols are designed to stay within safe limits, with breaks built in to reduce cumulative oxygen exposure.
Emerging Uses Under Study
Beyond its approved indications, HBOT is being studied for several conditions where results look promising but aren’t yet definitive.
Traumatic Brain Injury
HBOT may help after moderate to severe brain injuries by reducing swelling, lowering pressure inside the skull, and increasing both oxygen and glucose delivery to damaged brain tissue. A study tracking 133 patients five to eight years after their injuries found that 62.4% who received HBOT had only mild disability or none at all at follow-up, while 30.8% remained moderately disabled or worse. The data suggested that roughly 14 to 22 sessions may be an effective range depending on injury severity, though too many sessions could potentially diminish long-term benefit.
Cellular Aging
A prospective trial at Shamir Medical Center in Israel found that a course of 60 HBOT sessions increased telomere length (the protective caps on chromosomes that shorten with age) by over 20% across several types of immune cells. B cells showed the largest gains, with telomeres lengthening by roughly 37% after the full protocol. At the same time, senescent immune cells, the “worn-out” cells that accumulate with aging and drive inflammation, dropped significantly: helper T cells decreased by about 37% and cytotoxic T cells by about 11%. These are striking numbers, but this was a small, single-center study, and it’s not yet clear whether these cellular changes translate to meaningful health or lifespan differences.
Insurance and Cost
Medicare Part B covers HBOT for the approved conditions listed above, and most private insurers follow similar criteria. If your condition is on that list and properly documented, coverage is generally straightforward. For diabetic foot wounds specifically, you’ll need to show that the wound is severe enough and that standard wound care has already been tried without success.
For off-label uses like brain injury recovery, anti-aging, long COVID, or fibromyalgia, insurance typically will not cover treatment. Out-of-pocket costs for these sessions can add up quickly, especially when 40 or more treatments are recommended. Prices vary widely by facility and location, so it’s worth calling ahead for specific pricing if you’re considering HBOT for a non-covered condition.