Hyperbaric oxygen therapy (HBOT) involves breathing almost pure oxygen in a special room or small chamber.

Its main use is to treat diving-related illness, but it may enhance healing in people with various other conditions.

In 1662, a physician built the first hyperbaric chamber — a sealed room with a series of bellows and valves. The belief was that pressure could help treat certain respiratory diseases.

In the 1940s, HBOT became standard treatment for military divers in the United States.

However, while there are around 1,200 HBOT centers in the country, only two are mainly dedicated to treating diving injuries, according to the Divers Alert Network (DAN).

The Food and Drug Administration (FDA) have approved HBOT as a treatment for 13 conditions, but some people are calling for further approvals. Find out more about the benefits and risks of HBOT here.

Below, learn about the various therapeutic uses of HBOT.

Diving-related problems

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HBOT can help treat some diving-related problems.

Divers who surface too quickly are at risk of decompression illness (DCI). It happens when air bubbles form and expand in the body. The term DCI refers to decompression sickness (DCS), which some call “the bends,” an air gas embolism, or both.

Without treatment, these conditions can become life threatening within hours. Treatment for DCI can involve:

  • receiving oxygen
  • if necessary, spending time in a decompression chamber

HBOT returns the person to the pressure, or “depth,” at which they were diving. Then, it allows for gradual decompression, reducing the volume of the bubbles in the body.

DCI affects around 1,000 divers from the U.S. each year.

Other approved uses

The FDA have approved HBOT to help treat:

  • DCI
  • an air or gas embolism
  • anemia due to severe blood loss
  • some brain and sinus infections
  • carbon monoxide poisoning
  • burns resulting from heat or fire
  • skin grafts
  • necrotizing soft tissue infections
  • osteomyelitis, a bone marrow infection
  • arterial insufficiency, or low blood flow in the arteries
  • acute traumatic ischemia, which may involve a crush injury, for example
  • gas gangrene
  • a radiation injury, for example, as a result of cancer treatment

Evidence has shown that these uses are safe and effective. Insurance companies or Medicare usually cover the cost of FDA-approved HBOT treatment.

Some healthcare providers may use HBOT to treat other conditions, including a type of hearing loss.

Also, wounds and infections that have not responded to other treatment may respond to HBOT. For example, it may help reduce the need for amputation in people with diabetic foot ulcers.

Here, learn more about how diabetes can affect the feet.

Unapproved uses

A growing number of providers have started offering HBOT as an alternative therapy. Some call it a “miracle cure” and claim that it can help with a wide range of conditions.

HBOT chambers are appearing in various facilities, from hospital outpatient departments to spas. There are even chambers for home use.

While some of the claims may be true, the FDA have raised concerns about the risks of using HBOT “off label.”

The FDA point out that they have not approved HBOT as a treatment for the following:

A person should only receive HBOT for the approved purposes. Otherwise, a person could waste time and money and face a risk of side effects.

The FDA have warned that using HBOT for unapproved purposes may worsen the existing ailment.

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Large chambers can treat several people at one time.

The Undersea and Hyperbaric Medical Society (UHMS) is an international nonprofit organization set up in 1967 to support medicine related to diving.

They define HBOT as: “An intervention in which an individual breathes near 100% oxygen intermittently while inside a hyperbaric chamber that is pressurized to greater than sea level pressure.”

The body’s tissues need oxygen to function, and additional oxygen can help damaged tissue heal. Oxygen at high pressure can enhance tissue function and fight infection under certain conditions.

The ambient pressure inside the chamber is three times higher than the air pressure that people normally breathe. Breathing almost pure oxygen at this pressure can increase the concentration of oxygen available to the lungs by up to three times.

HBOT is usually an outpatient procedure, and a doctor will recommend a certain number of sessions, depending on a person’s condition.

For some people with carbon monoxide poisoning, one session is enough.

In some studies involving soft tissue necrosis, participants each received an average of eight treatments.

An HBOT session typically involves:

  • putting on a cotton medical gown
  • sitting or lying in a sealed chamber, either alone or with other people, in which case the chamber will be room-sized
  • receiving pressurized oxygen, which may arrive through a mask or a hood
  • talking with a therapist or technician during the session, if desired
  • possibly listening to music or watching TV to encourage relaxation

In a chamber for one, the person usually lies on a table that slides into a clear plastic tube.

The length of the session will depend on the reason for the treatment. A session may last 30 minutes to 2 hours. For chronic illnesses, DAN note that a session usually lasts around 2 hours.

A person with DCI may need to stay in the chamber for 2–5 hours.

In 2013, when the FDA advised against using HBOT for unapproved purposes, the Alliance for Natural Health responded by calling the announcement a “deceptive statement.”

Supporters call for HBOT to become a mainstream treatment for a wide range of conditions. They attest that pressure and additional oxygen can benefit various bodily functions and cite a number of studies that support their claims.

There are calls for HBOT to receive approval as an alternative therapy for autism, attention deficit hyperactivity disorder, better known as ADHD, cerebral palsy, post-traumatic stress disorder (PTSD), and others.

There is strong support in some circles for using HBOT to help improve the quality of life of veterans. Advocates say that the treatment may benefit those who have experienced traumatic brain injury (TBI) and those who have PTSD.

Researchers have been investigating the effects of HBOT on TBI. A 2016 meta-analysis found that HBOT may enhance the Glasgow Coma Scale score of a person with TBI but did not find enough evidence to support its use to treat PTSD.

Research into additional benefits of HBOT continues, but the FDA require more evidence before they can declare new uses safe and effective.

What causes PTSD, and how do you recognize it? Learn more here.

Inappropriate use of HBOT can lead to a number of adverse effects, as it involves oxygen at a high atmospheric pressure.

Adverse effects

Possible adverse effects include pain and damage to the:

  • ears
  • sinuses
  • eyes, including vision changes and cataracts
  • teeth
  • lungs

Some people also experience:

In rare cases, oxygen toxicity, or poisoning, can occur. Too much oxygen in the body’s tissues can cause convulsions and other complications.

People should not undergo HBOT if they have recently had a cold or fever, or ear trauma. People with a history of tinnitus, middle ear infections, pressure intolerance, or ear surgery may be at risk of ear damage.

Anyone considering HBOT should contact their doctor for advice before undergoing treatment. Seek treatment in an approved facility with trained staff who provide HBOT under FDA-approved conditions.

If Medicare or health insurance does not cover the cost of treatment, it may be because HBOT has not received approval for the particular use.

What is a ruptured eardrum? Find out more.

Unsafe facilities

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A person should speak with their doctor before undergoing HBOT.

HBOT chambers that do not comply with FDA approval may be unsafe or unfit for medical use.

Some providers offer the use of “soft” or “mild” chambers.

These have the following disadvantages:

  • They are unlikely to sustain the necessary pressure or guarantee the purity of the oxygen, resulting in ineffective treatment.
  • A power disruption could cause the chamber to deflate, leading to suffocation.
  • There is a risk of explosion and fire, as pure oxygen is highly explosive and flammable.

A study published in 2017 notes that, while HBOT has shown promise for wound healing and other uses, there is a lack of consistency in practice. The authors call for new protocols to standardize treatment.

HBOT is crucial for people with DCI and it can help treat carbon monoxide poisoning and other conditions.

The FDA currently approve only 13 uses for HBOT, but some people claim that it can have additional benefits.

People who undergo HBOT for unapproved uses may find that providers do not have the appropriate qualifications or that premises are unsafe or ineffective. They may waste money or experience long term adverse effects.

HBOT may turn out to have broader uses. But, as with other healthcare choices, it pays to be cautious.


Does breathing oxygen through a mask in a normal room have the same benefits for most people as HBOT?


No, it does not.

Breathing oxygen through a mask in a room with normal air pressure should increase the oxygen concentration carried by the hemoglobin of the red blood cells.

However, HBOT has an additional effect. Breathing pressurized oxygen activates the body’s ability to carry oxygen in the plasma. The combined effect on the red blood cells of carrying more oxygen and dissolved oxygen in the plasma is significant. This ability to carry oxygen in the blood plasma is especially important when hemoglobin cannot attach to oxygen molecules, such as in cases of carbon monoxide poisoning.

Deborah Weatherspoon, PhD, RN, CRNA Answers represent the opinions of our medical experts. All content is strictly informational and should not be considered medical advice.

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