Hyperbaric oxygen therapy (HBOT)

What it is and how it works

Normally, almost all the oxygen in the blood is transported by hemoglobin, and with healthy lungs it is almost fully loaded anyway. There is hardly room for more there. In the pressure chamber you breathe pure oxygen at markedly increased pressure, and then oxygen additionally dissolves physically in the plasma, many times the normal amount. The plasma itself becomes a carrier and reaches tissues where blood flow is weak: poorly healing wounds, radiation-damaged areas, zones of inflammation.

For the longevity use, a second idea comes in, the hyperoxic-hypoxic paradox. In the protocols, oxygen breathing is regularly interrupted by short air breaks. The switch from a great deal of oxygen to a normal amount is supposed to signal a shortage to the cells, even though they are swimming in abundance. The body responds much as it does to altitude training: with new blood vessel formation, regeneration programs and stem cell mobilization. The stimulus is the switch, not the steady state, the same hormesis principle as with fasting or cold.

Established medicine

Pressure chambers have been standard for decades in decompression sickness and gas embolism, along with carbon monoxide poisoning, chronic wounds such as diabetic foot syndrome, late effects of radiotherapy, certain bone infections and sudden hearing loss protocols. There is a network of specialized hyperbaric centers. This serious foundation is the reason the longevity scene took notice in the first place.

Even here, the evidence is not everywhere as strong as one might think. For carbon monoxide poisoning, the Cochrane analysis of six studies with 1,361 patients found no significant advantage over normal oxygen, though with great inconsistency between the studies.

The longevity studies from Tel Aviv

The research group around Shai Efrati and Amir Hadanny runs one of the largest HBOT research centers in the world. In 2020 the study that triggered the hype was published: 35 healthy people aged 64 and over completed 60 daily sessions. Afterwards, telomeres in several immune cell types were more than 20 percent longer, and senescent T helper cells were 37.30 percent fewer. There was no control group.

From the same group came two small randomized trials with 63 older adults each. In one, cognitive performance improved after three months compared with the control group, above all attention and processing speed, accompanied by more cerebral blood flow. In the other, maximal oxygen uptake rose by 1.91 milliliters per kilogram per minute, and blood flow to the heart improved. Added to these are studies on skin aging and on long COVID, in which the improvements lasted more than a year in a follow-up of 31 patients.

Practice, costs and user reports

In the studies, a session lasts 90 minutes at 2 atmospheres absolute pressure, with 5-minute air breaks every 20 minutes. You lie or sit, equalize pressure as on an airplane, and breathe through a mask or hood. Longevity protocols on the Israeli model comprise 60 sessions in three months; at prices of 120 to 250 euros per session, that ends up in the high four- to five-figure range.

After the first sessions, users report pleasant tiredness, a clearer head or better sleep, effects that are hard to measure. The actual remodeling, if it takes place, happens quietly over weeks. Important when checking providers: studios and home devices often work with soft chambers at 1.3 to 1.5 atmospheres and enriched air instead of pure oxygen. Physically, that is a different dose, and the results from Tel Aviv cannot be transferred to it. Oxygen bars without pressure practically do not increase dissolved oxygen in people with healthy lungs.

What the studies show

Hachmo 2020 — telomeres and senescent cells

35 healthy, independently living adults aged 64 and over, 60 daily sessions, blood samples before, during and 1 to 2 weeks after therapy. The telomere length of T helper, cytotoxic T, NK and B cells rose by more than 20 percent, most strongly in B cells at 37.63 percent after the end of therapy. Senescent T helper cells decreased by 37.30 percent, senescent cytotoxic T cells by 10.96 percent. No control group, no blinding, telomeres measured only in blood.

Hadanny 2020 — cognition, randomized

63 healthy adults over 64 were randomized to HBOT or control for three months. The primary endpoint was global cognitive function; it was reached, with p equal to 0.0017 for the group-by-time interaction. The largest effects were seen in attention, with an effect size of 0.745, and processing speed, with 0.788. The control group received no sham treatment.

Hadanny 2024 — endurance, randomized

63 sedentary adults over 64, 30 in the HBOT group and 33 in the control group, 60 sessions over 12 weeks. The primary endpoint was maximal oxygen uptake. It rose by 1.91 milliliters per kilogram per minute, effect size 0.455. Blood flow to the heart muscle also increased. Endpoint reached, again without sham treatment.

Cochrane 2015 — chronic wounds

12 randomized trials with 577 participants, 10 of them on diabetic foot ulcers. In the pooled data from 5 of these studies with 205 participants, more ulcers healed under HBOT after six weeks, relative risk 2.35. After one year, the advantage was no longer detectable, and the number of major amputations did not differ significantly. The authors consider the results uncertain because of flaws in design and reporting.

Where the data stop

The longevity data have three weaknesses. The telomere study was uncontrolled, and telomere measurements in blood cells are error-prone; independent replication is still pending. The two randomized trials compared HBOT with doing nothing, not with a sham treatment, even though cognitive tests in particular respond to expectation. And all studies come from the same center that also offers the therapy.

For sports recovery, the situation is thinner than its reputation. A 2026 systematic review found no significant benefit in randomized trials for post-exercise muscle soreness; there are better data for certain bone problems. In long COVID, 56 to 63 percent improved markedly in a registry, but 13 to 19 percent also got worse. Whether HBOT lets healthy people live longer in good health has not been studied by anyone.

Status, approval and legal

HBOT is a medical procedure, not a wellness product. In Germany, statutory health insurers cover treatment for severe diabetic foot syndrome from Wagner grade II after unsuccessful standard therapy and on referral, both outpatient and inpatient. Longevity, sports and long COVID uses are self-pay services. Before booking, five questions are worth asking: How much pressure and what percentage of oxygen? Is there a medical entry examination with an ear and lung check? Which protocol and which measurable goal? What does the whole package cost? And are sleep, exercise and nutrition already under control?

Safety

HBOT is considered one of the safest therapies, but it has known side effects. The most common is barotrauma of the middle ear when pressure equalization fails, which is why an ear check and instruction are part of it. After many sessions, temporary nearsightedness can occur, which resolves. Rare but serious are seizures due to oxygen toxicity of the nervous system at high pressure, one reason for medical supervision. An untreated pneumothorax rules out treatment; caution applies with severe lung disease, certain chemotherapies, pregnancy and claustrophobia. Pure oxygen increases the fire risk, hence the strict rules on what may be taken into the chamber. Divers schedule chamber sessions and dives at separate times.

Sources

• Hachmo et al., Aging (Albany NY) 2020 (telomeres, senescent cells)
• Hadanny et al., Aging (Albany NY) 2020 (cognition, RCT)
• Hadanny et al., BMC Geriatr 2024 (endurance, RCT)
• Kranke et al., Cochrane Database Syst Rev 2015 (chronic wounds)
• Buckley et al., Cochrane Database Syst Rev 2011 (carbon monoxide)
• Heyboer et al., Adv Wound Care 2017 (side effects)
• Weinrich et al., BMC Musculoskelet Disord 2026 (sport and musculoskeletal system)
• van Berkel et al., Sci Rep 2025 (long COVID registry)
• Hadanny et al., Sci Rep 2024 (long COVID, follow-up after one year)
• G-BA, press release of September 21, 2017 (outpatient HBO for diabetic foot syndrome)