Oxygen Toxicity And
Hyperbaric Oxygen Therapy

Oxygen Toxicity, Hyperbaric Oxygen Therapy

Questions about oxygen toxicity syndrome or oxygen intoxication are frequently asked by people undergoing hyperbaric oxygen therapy as well as scuba divers. Owner of this website is indebted to Robert L. Sands who kindly permitted to publish the following article...

This article will answer a number of important questions regarding oxygen toxicity and endeavor to do so in terms easily understood by health care scientists (M.D., D.D.S., D.O) who write Rx for the use of HBOT to educate them to adverse effects and benefits of hyperbaric oxygen therapy and also the layperson who may be influenced or intimidated by the opinions of others.

  • Q: Is there such a thing as "oxygen toxicity?"
  • A: Yes.
  • Q: Is oxygen toxicity good or bad?
  • A: Yes / No. Both answers are correct.
  • Q: Are the free radicals produced by HBOT good or bad?
  • A: Yes/No. Both answers are correct.
  • Q: Can a physician make an objective assessment that the patient "had too much oxygen and was suffering from oxygen toxicity" two or three days after HBOT had ceased?
  • A: No. This is just a medical opinion.

The third leading cause of death (after heart problems and cancer) in the United States are those caused by physician's errors, more than 250,000 lives lost Journal of the American Medical Association (JAMA volume 284, July 26, 2000.). To put it into perspective, an unnecessary casualty list equaling the 911 collapse of the World Trade Centers times ten each year!

It is appropriate that we look to the effects of breathing molecular oxygen under pressure, since many regular physicians caution their patients not to use hyperbaric oxygen therapy because of potential toxic events. Even though a serious search of Coroner's records throughout the United States will show no deaths due to breathing oxygen.

According to the Journal of the American Medical Association (JAMA volume 284, July 26, 2000). Doctors are the Third Leading Cause of Death in the U.S. Causing 250,000 Deaths Every Year. Iatrogenic (iatros Greek = physician, genic English = start) is a term defined as induced in a patient by a physician's activity, manner or therapy. Used especially in a complication of treatment.

  • 12,000 patients die during unnecessary surgery
  • 7,000 patients die from medication errors in hospitals
  • 20,000 patients die to other errors in hospitals
  • 80,000 patients die to infections from hospitals
  • 106,000 patients die from non-error, negative effects of prescription (Rx.) drugs

Note: Since these statistics are derived from hospital patients, the death rate could be much higher. Also, the statistics show only deaths and do not include negative effects that are associated with disability or discomfort.

Note: The statistics quoted herein are in no way meant to disparage the Healers of the medical profession. They do not reflect the huge (without number) of life-saving procedures. The purpose is merely to demonstrate that all medical response has risk and that hyperbaric oxygen therapy is likely to be an almost risk-free medical response.


Now to banish the dreaded "oxygen toxicity" myth that many newcomers to the field worry about – and that includes physicians as well as patients. Much has been written about it and many practitioners actually use this term to show just how clever they are to detect this toxicity in their patients and why patients should trust the "hyperbaric specialist's" subjective assessments of status.

Even the excellent and well-balanced explanation of oxygen toxicity on Wikipedia could well be alarming to the layperson. Yet buried in all of those words is this little paragraph:

The incidence of CNS [central nervous system] oxygen toxicity among patients undergoing hyperbaric oxygen therapy is rare and influenced by a number of factors: individual sensitivity and treatment protocol; and probably the equipment used. A study by Welslau in 1996 reported 16 incidents out of a population of 107,264 patients (0.015%), while Hampson and Atik in 2003 found a rate of 0.03%.[89][90] Yildiz, Ay and Qyrdedi, in a summary of 36,500 patient treatments between 1996 and 2003, reported only 3 oxygen toxicity incidents, giving a rate of 0.008%.[91]

Statistics show that breathing densely packed molecular oxygen—which is precisely what you do when you undergo hyperbaric oxygen therapy—is extremely safe. According to Philip James, medical director of the University of Dundee’s Wolfson Hyperbaric Medicine Unit, “Oxygen is the most researched drug on the face of the planet with no known side effects.” But if this is true, why the fuss?

It All Began As A Misunderstanding

To fully grasp the nature of oxygen toxicity, we have to go back down the manhole of history and see what these modern day medical practitioners are basing their alarming comments on. It is time to dispel the ghosts of World War II diving experience and the animal research of the Gemini and Apollo space era and recognize them as the important forbears of a highly effective and safe medicine—hyperbaric oxygen therapy or HBOT as it is now commonly known.

It all started back in the days of World War II when frogmen would swim the cold waters of the Atlantic using oxygen rebreathers. Because this gear, unlike scuba tanks, didn’t produce a telltale trail of bubbles that might alert sentries to their presence beneath the ocean’s surface, they could attach limpet mines to German boats and swim off without hand grenades being tossed at them during the mission. In some cases, when detected, these very cold and exhausted men swam deeper than 33 feet and had seizures.

"Oxygen toxicity" was presumed the cause at the time. The drowning obliterated the true culprit, which was likely a combination of hypothermia and hypoglycemia caused by their exhaustion. Simply put, their neurons could not scavenge enough sugar to meet the challenge of high density oxygen and they died.

During this same period, another phenomenon experienced by deep sea divers gave rise to the myth that “air breaks” (a short periods of breathing air for short periods, like five minutes, out of each thirty minutes while breathing 100% oxygen in a hyperbaric chamber) are necessary to prevent pulmonary oxygen toxicity. Any diver breathes very dry gas, whether he or she is breathing from an oxygen rebreather or from a scuba tank. This results in dry throats and dry lungs. For a few minutes after long deep exposure to these breathing conditions, some areas of the divers’ lungs crackle like the sound you get when squishing up paper. The medical term is atelectasis.

oxygen toxicity and its effects are transitory

Back in the WWII days, researchers measured this condition and produced what they termed the Units of Pulmonary Oxygen Toxicity Dosage ("UPTD"). The "toxicity" that they measured, however, is temporary. The crackling sound made by the divers’ lungs or, more specifically, made by the areas of alveolar surfactant within their lungs that become dehydrated after breathing pressurized gas, lasts only five minutes or so in a normobaric environment (under normal atmospheric pressure), after which full lung function returns.

What this means for the patient undergoing hyperbaric treatment is that air breaks—the five minutes of air breathing during HBOT/HDOT (high oxygen dosage treatment) sessions—are not needed at all.

As it turns out, most of the texts cited when discussing pulmonary oxygen toxicity stem from World War II and thread their way through the animal experiments of the Gemini and Apollo expeditions. Here, at the dawn of the Space Age, it was confidently anticipated that astronauts could breathe 100% oxygen for months at a time without any health risk. But the animal experiments showed changes in lung structure that caused researchers to rethink their assumption.

The science of the 1950s and 1960s has since been eclipsed by newer research into hyperbarics. Studies performed as recently as 2009 show no lung damage occurs at all when consecutive daily treatments of 100% oxygen are given—no matter what the standard therapeutic pressure dose is for that treatment. Most importantly, as mentioned in the discussion above about atelectasis, any changes in lung tissue quickly evaporate before the next day’s treatment.

Stephen Thom, MD, Ph.D., a professor and the chief of hyperbaric medicine at the Hospital of the University of Pennsylvania, also observed this resiliency when investigating the relationship between consecutive daily HBOT treatments and toxicity in a study funded by the National Institutes of Health. In the American Journal of Physiology-Heart and Circulatory Physiology, Thom shares his finding that: "[a]ural barotrauma occurs in a small number of patients, and rare occurrences of biochemical O2 toxicity to eyes, lungs, and the central nervous system are virtually always reversible." Thom, S (2006). “Stem Cell Mobilization by Hyperbaric Oxygen”, American Journal of Physiology-Heart and Circulatory Physiology 290(1378-1386).

oxygen toxicity has therapeutic properties

Our Centers exploit HBOT/HDOT toxicity to eradicate such terrors as gangrene, methicillin-resistant Staphylococcus aureus (MRSA) and life-threatening fungi such as mucor. This is in line with recommendations by neurologist and neurosurgeon K.K. Jain, who co-wrote The Textbook of Hyperbaric Medicine, which is considered the seminal resource on HBOT. Jain advocates harnessing the therapeutic power of oxygen toxicity and suggests HBOT as a means for doing so. On page 58, he writes, “Induced oxygen toxicity by HBO… should be investigated as an adjunctive treatment for AIDS because the virus responsible for this condition has no protective mechanism against free radicals.”

In March of 2009, a physician prescribed HBOT for an AIDS patient who was considered to be at the end-stage of his disease process. The patient was treated at a Healing Chambers International Center. In a seven day period of HBOT treatments, the patient’s lab reports showed that his HIV viral load dropped from 2171 to 157—a tenfold decrease. The patient gained weight and went off all pain medications.

Hyperbaric oxygen treatments have been used to eradicate seizure disorders.

Let's get back to what happened to those frogmen of World War 2 and examine how oxygen toxicity affects the central nervous system, neurons and the body’s other cells. Most modern day seizures that occur in hyperbaric chambers are due to these factors—minus the cold Atlantic water. Paradoxically, the actual clinical experience of children who undergo repeated HDOT (HBOT) treatments have seen their seizure disorders permanently disappear.

Frederick Cramer, MD, of the San Francisco Institute for Hyperbaric Medicine, is a leading proponent of using HBOT treatment for epilepsy as an alternative to a lifetime of anti-seizure medications. Over the past 25 years, he has experienced significant success with patients using this modality and is launching a new pilot study to gather additional data about its efficacy.[6]

Cramer has also documented the application of HBOT to facilitate patients’ recovery from surgical operations. “The ability of HBO[T] to improve wound healing traditionally has been attributed to increased availability of molecular oxygen at the wound site,” he explains in his book, Hyperbaric Oxygen, Perioperative Care. “However, new research tools and techniques have led to a tremendous expansion in our understanding of the cellular and sub-cellular interactions that make up the ‘healing process’.”

He names several of the innovations that are enhancing our understanding about exactly how hyperbaric oxygen treatment works: immuno-fluorescent staining, DNA and RNA sequence identification, DNA growth factor transfection techniques, Polymerase Chain Reactions (PCR), reverse transcriptase PCR (rt-PCR), Southern Blot tests, Fluorescent In-situ Hybridization (FISH) electron microscopy, recombinant gene therapy.

Thus, as science moves forward, it leaves less room for speculation and fear about hyperbarics and oxygen toxicity. So remember, the next time anyone warns you about the hazards of oxygen toxicity, be sure to ask that they show you the evidence.

A Final Note On Oxygen Toxicity…

Eavesdropping on one of the great pioneers in hyperbaric medicine, the late Dr. Richard Neubauer, as he observed his friend (the nuclear physicist and renowned father of the hydrogen bomb) Dr. Edward Teller receive HBOT therapy, we learn that Edward received hyperbaric treatments 6 days a week (2.5. ata) for a total of over 3,000 treatments with no signs of toxicity whatsoever. He operated on a genius level and continued his work until just days before he died…at the age of 95 on September 9, 2003.