In case you missed it, HBOT is the most proven treatment for Long COVID

The most reliable scientific evidence comes from double-blind randomized controlled studies. There have only been a handful of those for Long COVID or similar conditions:

  • Hyperbaric oxygen therapy (HBOT)
  • Leronlimab, a CCR antagonist
  • AXA1125
  • Phyto-V (RCT link)
  • IVIG for post-polio syndrome (and other conditions), which may be unrelated to Long COVID
  • Rituximab for ME/CFS, which should be more like Long COVID than post-polio syndrome

Links to the RCTs can be found at the List of doctors and approaches - Long Haul Wiki

Phyto-V - why I don’t trust the published science on this Phytochemical capsuleOf the RCTs listed above, only 2 of them had positive statistically significant results. I won’t talk about Phyto-V here because it probably needs its own post. The Phyto-V data may be unreliable because Robert Thomas has potential conflicts of interest with So that leaves us with HBOT…

The Shamir Medical Center RCT

Shamir Medical Center in Israel funded a randomized controlled trial of HBOT on Long COVID patients. It compared HBOT at 2ATA (with oxygen) to ‘sham’ HBOT that was as mild as possible to give the impression of HBOT treatment. Both the high-pressure HBOT group and the ‘sham’ control group experienced a few cases of barotrauma. The blinding was fairly good as “the correct group allocation perception rate was 54.1% and 66.7% (p=0.271) in the HBOT and control groups respectively”.

One strength of the trial was that endpoints were pre-registered (NCT04647656) to ensure that the results are reliable and free of data mining. The trial met its primary endpoint of cognitive improvement as measured by Neurotrax, a computerized set of tests that objectively measures cognitive performance.

How to get more information: The study results paper can be found at Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition: randomized controlled trial | Scientific Reports

Safety considerations with HBOT

For some reason, a few people seem to react very badly to HBOT on the first session or within the first few sessions. This seems to happen even at lower pressures.

One anecdote: Veronica Smith reported worsening after 9 sessions at 1.5 (?and 2?) ATA. Negative symptoms became clearer following dives 4 and 5.

Here’s survey data showing the same idea. The rate of mild and significant worsening is roughly the same between low and high pressure HBOT.

To save some money, you can start with lower pressures to see if you will react and to reduce your exposure to HBOT. Lower pressures = less HBOT.

Oxygen toxicity

An animal study found that excessive HBOT can lead to death in lab animals. See Warren et al. (DOI:10.4049/jimmunol.121.1.315). Human patients also report the same thing. So after 10-40 sessions, you may want to start paying attention to whether or not HBOT is making your symptoms worse rather than better.

Fire hazard

One of the ways to try to save money/time is to buy a soft shell chamber and to sleep in it (so that it doesn’t take “time” to do your HBOT). You would be sleeping in a fire hazard because oxygen and pressure makes fire burn faster.

So… you really need to know what you’re doing if you try something like that.

Herx reactions

If you have Lyme or spirochete bacteria dying off, you may experience serious side effects. However, if you can confirm that a Herx reaction is happening (e.g. previous similar reaction with antibiotics), it may be worthwhile to use HBOT to slowly kill off bacteria under competent medical supervision. Horowitz is a Lyme doctor who explains Herx reactions in this video.

However, be careful about doctors who have a financial incentive to mis-diagnose you with a Herx reaction. There are some bad doctors who will try to hide their mistakes/ignorance/grift by blaming bad outcomes on a “Herx” reaction - see the thread on it.


Only a small portion of people seem to really benefit from HBOT- there’s some additional data here in the ‘what worked’ video. If you aren’t noticing results within the first several session of high-pressure HBOT, then you don’t need to throw your money down a pit.

If you scroll up to the charts, you can see that most people don’t report significant improvement. It also turns out that the survey data is optimistically biased so people will report slightly improvement for treatments that may be doing nothing.

High pressure versus low pressure

Unfortunately, the higher pressure HBOT seems to be delivering more benefit than lower pressure HBOT. It is a lot more expensive. Whereas you can spend several thousand dollars to $15K to buy a soft shell chamber, buying a hard shell chamber capable of higher pressures is not so straightforward.

I don’t know if you can make that up by doing a lot of low-pressure HBOT. I just haven’t seen data on that yet.

The UK

The UK has a series of charities that provide HBOT at a lower cost.

The bottom line

While cost will be a barrier for some people, this is the most proven treatment for Long COVID. Hopefully other treatments will have high-quality studies supporting their use so that other treatments involves less guesswork and dice rolling. I certainly don’t think that HBOT is the only treatment you should look at, especially because most people won’t respond to it.

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Anecdotes of long-lasting worsening


After that 10th day I never went again, but every night since I’ve been waking up at 3 or 4 am with massive adrenaline dumps. It basically feels like my fight or flight is on overdrive and I’ll wake up feeling like adrenaline, fear, and stress is pumping through my body, especially heart (sort of like hyper-adrenal dysautonomia). I’m usually unable to fall back asleep and it’s been pretty awful.

Agy_lena (ME/CFS):

HBOT for example. That made me permanently worse.

Veronica Smith reported worsening after 9 sessions at 1.5 (?and 2?) ATA. Negative symptoms became clearer following dives 4 and 5.

Somebody I know paid for 40 sessions but never went back after the first sessin.

Some colour on the conflicts of interest with the RCT involving Shai Efrati:

Shai Efrati is a shareholder in Aviv Scientific as well as an employee of the Sagol Centre whose whole goal it is to roll out a very wide network of HBOT clinics all over the world.

In their first paper they still declared a conflict of interest Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition: randomized controlled trial | Scientific Reports, “Amir Hadanny and Efrat Sasson work for AVIV Scientific LTD. Shai Efrati is a shareholder at AVIV Scientific LTD. LTD. SZI, MC, KES, EL, SF, NP, GF, CK, RS, YP, MS have no competing interests.”

“Aviv Scientific is a leader in research on age-related cognitive and functional decline and novel applications of hyperbaric medicine to maximize human performance. Aviv focuses on improving the aging process by increasing cognitive and physical performance in healthy aging adults. Based on an exclusive global partnership with the world’s largest Hyperbaric medicine and research facility, the Sagol Center at Shamir Medical Center in Israel, Aviv Scientific is rolling out a global network of medical clinics focused on the enhancement of cognitive and physical performance with hyperbaric medicine and related technologies at its core. “ Improving Cognitive and Physical Decline | Aviv Scientific

In subsequent papers they don’t declare any conflict of interest anymore see for example The effect of hyperbaric oxygen therapy on myocardial function in post-COVID-19 syndrome patients: a randomized controlled trial | Scientific Reports “The authors declare no competing interests.”

If you read the studies on HBOT you will see that they are not very convincing. After all they aren’t LC researchers but simply HBOT researchers that apply HBOT to anything, which is fair enough.


The people who ran the Shamir Medical Center RCT are claiming that the benefits stick around after a year. Here’s their updated paper.

The clinical improvements gained by HBOT are persistent even 1 year after the last HBOT session.

The Aviv clinics guy throwing shade at competing HBOT… not great for patients

Shai Efrati was one of the key people behind the HBOT RCT. He is clearly affiliated with Aviv clinics (which sells high pressure HBOT) but he no longer discloses that conflict of interest in his papers.

In an interview on the Aviv clinics Youtube channel, he talks describes high pressure HBOT as “very safe”, which is not how I would characterize HBOT.

51:47 Be evaluated by a professional. He will evaluate you and once he will say that you are suitable then the treatment is generally very safe.

The survey data does show that some patients do respond very negatively to HBOT. Here’s some data from the latest Patient Experiences Survey (TOS data was shown earlier in this thread).

And as mentioned earlier, oxygen toxicity can be an issue.

One problem with getting “professional” medical advice from a HBOT clinic is that they have an incentive to sell you HBOT. What we’ve seen in the US dialysis industry is that rates of in-clinic dialysis are higher in the US than Canada because only the US doctors are allowed to profit from steering their patients towards in-clinic dialysis. I would expect the conflict of interest in HBOT to cause some doctors to steer their patients towards too much HBOT. Perhaps they may even ignore HBOT treatment going the wrong way.

We also see Efrati show his bias towards competing HBOT - namely the soft shell HBOT chambers that he shows in his presentation.

42:56 many people are buying by Amazon or whatever it is and put them on the backyard this is not it don’t get into that this is not working it can be dangerous this is actually less than our placebo group if you need the treatment your health is important go to professional who knows what they are doing

“actually less than our placebo group” is saying that the soft shell chambers achieve lower pressures. Their placebo group received a brief spurt of 1.2 ATA.

To mask the controls, the chamber pressure was raised up to 1.2 ATA during the first five minutes of the session along with circulating air noise followed by decompression (0.4 m/min) to 1.03 ATA during the next five minutes.
Hyperbaric oxygen therapy improves neurocognitive functions and symptoms of post-COVID condition: randomized controlled trial | Scientific Reports

However, this is an unfair dig on cheap HBOT chambers as many of them achieve pressures of 1.3, 1.4, and even 1.5 ATA.

His second dig on cheaper HBOT is that they are “dangerous” whereas his clinic’s HBOT is not. I would not characterize it that way… the data shows that both can cause harm to chronic illness patients. He has a clear bias towards what he is selling and that is not something that you want to see as a patient.

Here’s one person’s thoughts on why they didn’t try HBOT. I don’t agree with most of it but a few of the points are good, e.g. three of the authors of one of the HBOT papers have conflicts of interest.

Evaluating HBOT for Long COVID