What Is Hyperbaric Oxygen Therapy (HBOT)?

Also Known as Hyperbaric Chamber Treatment

Hyperbaric chamber therapy or hyperbaric oxygen therapy (HBOT therapy) is a medical treatment in which sit in a hyperbaric chamber, an enclosed space filled with pure oxygen. Air pressure is kept two or three times greater than normal to help the body take in more oxygen, which can help heal wounds, treat carbon monoxide poisoning, and more.

Hyperbaric oxygen therapy was first used in the U.S. in the early 1900s. Later, it was used to treat decompression sickness, a hazard of scuba diving. Today, HBOT therapy is prescribed and supervised by medical institutions for a host of health and wellness issues, and it may even be covered by insurance (depending on your coverage and the condition it’s used to treat). 

This article explores how hyperbaric chambers work and what type of ailments HBOT therapy is commonly used to treat. It covers controversial issues related to the treatment and what the research say about its efficacy and safety.

How to prepare for hyperbaric chamber treatment
 Verywell / Brianna Gilmartin

How Does HBOT Therapy Work?

One method of HBOT therapy involves a person receiving the treatment inside of a tube-like chamber. Some tubes are made of clear acrylic, allowing patients to see outside of the chamber. This transparency may eliminate some of the potential anxiety a person may have of feeling trapped inside the tube.

During HBOT therapy, a patient is instructed to lie down in the enclosed chamber and breathe the air inside the tube as the pressure is gradually increased.

Another mode of treatment, such as that offered at Mayo Clinic, is a multiperson hyperbaric oxygen room, where oxygen is delivered via a mask or a lightweight clear hood placed over the head. In this scenario, a person can sit or lie down in a lounge chair—there is no tube or chamber with this method.

HBOT therapy treatment sessions can last up to two hours. The number of treatments prescribed depends on the condition that HBOT therapy is being used to treat. 

For example, for a condition such as carbon monoxide poisoning, it's suggested that the patient undergo up to three sessions. This time span will vary with other conditions that are being treated.

Increased Oxygen

There is no way of controlling how much oxygen gets absorbed into the body. HBOT is a way to hypothetically turn up the volume of oxygen absorption by increasing the atmospheric pressure. The pressure inside the chamber is normally two to three times greater than outside air pressure, which means patients are inhaling 100% oxygen.

Hyperbaric chambers work by providing oxygen that can be controlled. Normally, oxygen is transported throughout the body—after it initially gets absorbed by the lungs­­—then circulates to all the tissues and organs via the heart and blood vessels.

HBOT therapy allows for oxygen to be dissolved in the blood, body fluids, cerebral spinal fluid (the fluid that surrounds the brain and spinal column), bone tissue, and lymph node. Oxygen-rich fluids in the body can then travel to areas where blood circulation is blocked. 

HBOT therapy is said to help the body by assisting with the following functions:

  • Helping the immune cells of the body to kill bacteria
  • Reducing inflammation
  • Allowing for collateral circulation (growth of new blood vessels to provide extra oxygen to affected areas of the body)


The body needs oxygen to heal itself. Many injuries and illnesses result in a disruption of oxygen-rich blood, being able to travel to affected areas of the body.

For example, diabetes can result in poor and slowed circulation, making it more difficult for oxygen-rich red blood cells to reach wounded areas of the skin. This results in injuries that are very slow to heal or injuries that do not heal at all.

HBOT therapy has been used to treat many different medical conditions and injuries that benefit from having an increased level of oxygen in the tissues. Hyperbaric oxygen therapy can be utilized as a stand-alone treatment or a procedure that can boost the action of medications, such as antibiotics.


Some of the common uses for hyperbaric oxygen therapy that are often covered by insurance include:

  • Arterial gas embolism (air bubbles in the blood vessels)
  • Carbon monoxide poisoning (from breathing noxious fumes)
  • Cyanide poisoning
  • Decompression sickness (a common scuba diving condition, also called "the bends")
  • Specific types of non-healing wounds such as diabetic wounds
  • Gas gangrene (fast-spreading gangrene in infected wounds that gives off a foul-smelling gas)
  • Intracranial abscess (originating from an ear infection, sinus infection, or another primary source of infection)
  • Tissue damage from radiation therapy
  • Osteomyelitis (long-term inflammation of bone or bone marrow)
  • Compromised skin grafts or flaps
  • Severe anemia
  • Brain abscess
  • Burns
  • Crushing injury
  • Sudden deafness
  • Sudden, painless vision loss

Further Conditions

There are several other types of injuries and illnesses that are said to benefit from HBOT therapy, but there is a lack of clinical research evidence to back up many of these claims. Therefore, these conditions are not usually covered by insurance:

  • Lyme Disease
  • Near drowning
  • Recovery from plastic surgery
  • Allergies
  • Alzheimer's disease
  • Arthritis
  • Asthma
  • Autism
  • Bell's palsy
  • Brain injury
  • Cancer
  • Cerebral palsy
  • Chronic fatigue syndrome
  • Cirrhosis
  • Depression
  • Fibromyalgia
  • Gastrointestinal ulcers
  • Heart disease
  • Heatstroke
  • Hepatitis
  • Migraine
  • Multiple sclerosis
  • Parkinson's disease
  • Spinal cord injury
  • Sports injury
  • Stroke
  • Traumatic brain injury

Can a Hyperbaric Chamber Help COVID?

Some research shows that HBOT therapy seems to be a safe and effective treatment for COVID-19. However, the FDA has yet to clear HBOT therapy for treating COVID infection at this time.

Side Effects

Although hyperbaric chamber treatment is considered a natural and relatively safe mode of therapy, there are some side effects involved.

These include problems with the sinuses and ears (such as popping in the ears) due to the sudden changes in atmospheric pressure, fluid buildup or rupture in the middle ear, temporary changes in vision causing nearsightedness, lung collapse (called barotrauma) from air pressure changes, and oxygen toxicity (a side effect from receiving excessively high concentrations of oxygen).

Oxygen poisoning can cause lung failure, fluid in the lungs, or seizures. According to Johns Hopkins Medicine’s Health Library, taking frequent breaks to breathe regular air during HBOT can help prevent oxygen poisoning.

Another hazard of HBOT is fire. Pure oxygen can cause a spark to easily ignite into flames. Therefore, in preparation for HBOT, it’s important not to have any lighters or battery-powered devices in the treatment area. Eliminating petroleum-based or flammable skincare or hair products from your body is also important.   

The side effects of HBOT are usually mild and temporary, provided some safety measures are followed. These safety measures include administering HBOT for no longer than two hours in per session. Also, the pressure inside the chamber should be less than three times that of the pressure in the atmosphere.

Can Hyperbaric Oxygen Therapy Cause Heart Problems?

There have been few reports of atrial fibrillation (irregular heart rhythm) after HBOT therapy, but it's rare, and more research is needed before any clear link can be made. In general, heart problems are not considered a side effect of HBOT therapy.


Do not consider having HBOT therapy with these conditions:

  • Lung conditions (because of the increased risk for a collapsed lung)
  • A cold
  • A fever
  • A recent ear surgery
  • A recent injury
  • Claustrophobia (fear of small spaces)


Before an HBOT therapy session, it’s important to shower and avoid all perfumes, deodorants, and hair sprays (and styling products). Wigs and jewelry are not allowed inside the chamber. Alcohol and carbonated drinks should be avoided for at least four hours before HBOT.

Smokers are encouraged to quit smoking during the time span that they receive therapy because tobacco products block the body’s natural ability to transport oxygen.

To minimize problems with ears and sinuses, techniques (such as yawning or swallowing) are taught for adequate clearing of the ears. Sometimes tubes are inserted into the ears to minimize issues that result from pressure in the ears during HBOT.

The following are questions that healthcare professionals commonly ask before treatment:

  • Do you have any cold, nasal congestion, or flu symptoms?
  • Do you have a fever?
  • Are you pregnant?
  • Have you eaten prior to treatment?
  • If you have diabetes, did you take your insulin before treatment?
  • Has there been any recent change in your medications?
  • Do you have anxiety?

Once HBOT therapy is completed, there are no activity or dietary limitations that follow.


There have been research findings from clinical research studies on the safety and effectiveness of hyperbaric chambers for various maladies.

Skin Grafts and Flaps

One study examined the efficacy of HBOT used to treat tissue grafts and flaps. The findings concluded that HBOT can "increase the likelihood of composite graft survival, improve skin graft outcomes, and enhance flap survival."

The study authors also explain that HBOT therapy is “not indicated for healthy, non-compromised tissue, but is a valuable salvage adjunct in the treatment of threatened grafts and flaps."

Traumatic Brain Injury

In human studies involving those with severe traumatic brain injury (TBI), HBOT therapy was deemed a “promising, safe, therapeutic strategy for severe TBI patients." Note, this does not mean that there is clear evidence that HBOT is effective for traumatic brain injuries—more research studies are needed in this area. 


In one report by the United States Government Accountability Office, three article reviews found that hyperbaric oxygen therapy was safe. 

Cerebral Palsy (CP)

Although HBOT has been touted as one of the most effective procedures for cerebral palsy, one double-blind placebo study (the gold standard of clinical research studies) discovered that HBOT was no different than pressurized air for kids with CP.


According to Dan Rose, M.D., in an American Family Physician journal entry, “Hyperbaric oxygen therapy (HBOT) is associated with remission rates [a period during which symptoms of a disease are reduced or disappear] of 81% to 85% at two to three years in patients with chronic refractory osteomyelitis.”

Chronic refractory osteomyelitis is an infection in the bone that lasts longer than six months (regardless of antibiotic therapy and other appropriate medical treatment).

A Word From Verywell

Although hyperbaric chamber therapy is not yet thought of as a type of mainstream medical treatment, there is clinical research evidence that backs the efficacy and safety of this treatment for several conditions. However, there isn’t enough evidence to back up many of the claims for common uses of HBOT.

As with any other healthcare treatment modality, it’s vital to do some research and even consult with your healthcare provider or healthcare professional before undergoing HBOT.

Frequently Asked Questions

  • What are alternatives names for hyperbaric oxygen therapy?

    Hyperbaric oxygen therapy (HBOT) also is called recompression therapy.

  • What does hyperbaric chamber therapy feel like?

    Most people find it quite pleasant and relaxing. A common experience as the pressure in the chamber builds is ear "popping"—a sensation similar to that as a plane gains altitude in the air. Occasionally, people report feeling woozy during treatment and, afterward, as if they've just done a cardio workout.

  • What do you do in a hyperbaric oxygen chamber?

    Depending on the type of chamber, you either sit in a comfortable chair or lie down. You may wrap yourself up in a blanket if you like and simply rest. Often, HBOT chambers are outfitted with televisions and other forms of entertainment.

  • What kinds of hyperbaric chambers are there?

    There are two types of hyperbaric chambers:

    • Monoplace chambers are clear acrylic tubes designed for one person and shaped and sized so you can lie down during treatment.
    • Multiplace chambers may resemble a small airplane cabin. They contain comfortable chairs and are outfitted with clear hoods attached to a hose through which oxygen flows for each person.
  • Is hyperbaric chamber therapy safe during pregnancy?

    One two-hour session of HBOT is safe and recommended to treat carbon monoxide poisoning during pregnancy. The treatment is considered beneficial for both mother and baby. More than one session may be harmful to a developing fetus.

  • Who is not a candidate for hyperbaric oxygen therapy?

    Hyperbaric oxygen therapy is not recommended for people who have a cold, fever, recent injury or ear surgery, or claustrophobia. HBOT therapy is also not recommended for people with lung conditions, due to the increased risk of lung collapse.

13 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Mayo Clinic. Hyperbaric oxygen therapy.

  2. Oliaei S, Ahmed S, Alinaghi S, et al. The effects of hyperbaric oxygen therapy (HBOT) on coronavirus disease-2019 (COVID-19): A systematic review. Eur J Med Res. 2021 Aug;26(1):96. doi:10.1186/s40001-021-00570-2

  3. U.S. Food & Drug Administration. Hyperbaric oxygen therapy: Get the facts.

  4. Johns Hopkins Medicine. Complications of hyperbaric oxygen treatment.

  5. Celbek G, Boz BV, Caglar SO, Aydin LY, Kandis H, Saritas A. Paroxysmal atrial fibrillation after hyperbaric oxygen therapy. Am J Emerg Med. 2013 Jan;31(1):261. doi:10.1016/j.ajem.2012.03.021

  6. Baynosa RC, Ashish F. Hyperbaric oxygen therapy for the compromised graft or flap. Advanced Wound Care (New Rochelle). 2017;6(1): 23–32. doi:10.1089/wound.2016.0707

  7. Wang Y, Chen, D, Chen G. Hyperbaric oxygen therapy for traumatic brain injury. Medical Gas Research. 2014;4.18. doi:10.1186/2045-9912-4-18

  8. GAO Staff. Research on hyperbaric oxygen therapy to treat traumatic brain injury and post-traumatic stress disorder. United States Government Accountability Office.

  9. Lacey DJ, Stolfi A, Pilati LE. Effects of hyperbaric oxygen on motor function in children with cerebral palsy. Annals of Neurology; 2012;72(5):695-703. doi:10.1002/ana.23681

  10. Rose D. Hyperbaric oxygen therapy for chronic refractory osteomyelitis. American Family Physician. 2012;86(10):888-889.

  11. Arslan A. Hyperbaric oxygen therapy in carbon monoxide poisoning in pregnancy: Maternal and fetal outcomeAm J Emerg Med. 2021;43:41-45. doi:10.1016/j.ajem.2021.01.007

  12. Michigan Health. What to Know Before Receiving Hyperbaric Oxygen Chamber Therapy. Mar 3, 2020.

  13. Emerson Hospital. What Is Hyperbaric Oxygen Therapy? How a Space-Age Tube Can Heal Wounds and More. Mar 19, 2021.

By Sherry Christiansen
Sherry Christiansen is a medical writer with a healthcare background. She has worked in the hospital setting and collaborated on Alzheimer's research.