What Is Hyperbaric Oxygen Therapy (HBOT)?
Hyperbaric oxygen therapy combines increased atmospheric pressure with oxygen breathing to increase the amount of oxygen available in the blood and tissues. Here is what that actually means, how HBOT works, what it is used for, what a session feels like, and where medical treatment differs from wellness hyperbaric use.
Hyperbaric Oxygen Therapy in Simple Terms
Hyperbaric oxygen therapy (HBOT) is a treatment in which a person is exposed to pressure higher than normal atmospheric pressure while breathing oxygen. Increased pressure allows more oxygen to dissolve into blood plasma, which can increase oxygen delivery to tissues beyond what is possible with oxygen breathing at normal atmospheric pressure.
In physician-directed medical HBOT, the pressure, oxygen dose, session length, treatment frequency, equipment and clinical indication form part of a defined medical protocol. Hyperbaric chambers are also used in wellness and recovery environments, but those applications should not automatically be considered equivalent to clinical HBOT.
What Happens to Oxygen Under Increased Pressure?
The main difference between normal oxygen breathing and hyperbaric oxygen exposure is pressure. Increasing ambient pressure changes how gases behave and allows more oxygen to dissolve directly into the liquid portion of the blood.
Ambient Pressure Increases
The chamber is gradually pressurized above normal atmospheric pressure. The exact target pressure depends on the chamber, application and protocol.
More Oxygen Dissolves in Plasma
Higher oxygen partial pressure allows more oxygen to dissolve directly into blood plasma in addition to oxygen already carried by hemoglobin.
Oxygen Diffusion Gradient Rises
Greater circulating oxygen availability can create a stronger gradient for oxygen movement from blood toward nearby tissues.
Pressure Also Affects Gas Bubbles
Increased pressure can reduce the volume of gas bubbles, an important direct pressure effect in decompression sickness and air or gas embolism.
Breathing Oxygen at Normal Pressure Is Not the Same as HBOT
Supplemental oxygen at normal atmospheric pressure can increase the oxygen you breathe, but hyperbaric exposure adds another variable: increased ambient pressure. That pressure changes oxygen partial pressure and the amount of oxygen that can dissolve in plasma. This is why HBOT cannot be accurately described simply as “breathing more oxygen.”
What Is Hyperbaric Oxygen Therapy Used to Treat?
Physician-directed HBOT has established roles in selected medical conditions where increased pressure, increased oxygen delivery, or both can provide a specific therapeutic effect. The examples below are not a self-treatment checklist.
Medical HBOT should be prescribed according to diagnosis, patient screening, treatment pressure, oxygen dose, treatment duration and an appropriate clinical protocol. In the United States, HBOT devices are regulated as Class II medical devices and cleared through the FDA 510(k) process.
Read FDA HBOT Safety Information →Decompression Sickness
Recompression helps reduce gas bubbles formed following inappropriate decompression, particularly in diving-related illness.
Air or Gas Embolism
Increased pressure can reduce gas-bubble volume while increased oxygen availability supports affected tissues.
Carbon Monoxide Poisoning
Clinical HBOT may be used in selected carbon monoxide poisoning cases to accelerate carbon monoxide elimination and restore oxygen delivery.
Selected Non-Healing Wounds
Some difficult wounds, including selected diabetes-related wounds, may receive HBOT as one part of a comprehensive specialist wound-care program.
Delayed Radiation Injury
Hyperbaric treatment may be used for selected radiation-related tissue injuries where vascularity and tissue oxygenation have been impaired.
Crush Injury & Acute Ischemia
In selected serious traumatic injuries, HBOT may be used alongside appropriate surgical and medical care.
Gas Gangrene
Hyperbaric oxygen may form part of treatment for clostridial myonecrosis together with urgent surgical and antimicrobial management.
Refractory Osteomyelitis
Selected chronic bone infections that do not respond adequately to standard treatment may be considered for adjunctive HBOT.
Compromised Grafts & Flaps
HBOT may be considered when selected grafts or flaps have compromised blood supply and require specialist management.
Necrotizing Soft-Tissue Infection
In selected severe infections, HBOT may be used only as an adjunct to urgent surgery, antibiotics and intensive care.
Severe Anemia
Selected cases where blood transfusion cannot be used may involve hyperbaric oxygen as part of specialist medical care.
Selected Sudden Hearing Loss
Certain cases of sudden sensorineural hearing loss may involve HBOT within an appropriately timed specialist protocol.
Medical HBOT vs Wellness Hyperbaric Use
The terms “HBOT,” “mild hyperbaric therapy,” “hyperbaric oxygen wellness” and “oxygen chamber” are often used interchangeably online, but they do not necessarily describe the same protocol, equipment or intended use.
| Question | Physician-Directed Medical HBOT | Wellness / Recovery Hyperbaric Use |
|---|---|---|
| Primary Purpose | Treatment of a specific diagnosed medical condition under an appropriate clinical protocol. | General wellness, relaxation, lifestyle, recovery-oriented routines or non-medical services. |
| Pressure | Defined by the medical indication and treatment protocol. Clinical references commonly describe pressures substantially above normal atmosphere. | Often lower or moderate pressure, although chamber capabilities vary widely by model. |
| Oxygen | A defined medical oxygen dose delivered according to the chamber type and clinical protocol. | Oxygen delivery method and concentration vary by system and should be confirmed for the exact chamber. |
| Supervision | Clinical assessment, prescription, patient screening and appropriate professional monitoring. | Depends on the facility, intended use, local requirements and chamber configuration. |
| Medical Claims | Must correspond to recognized indications, device labeling and applicable regulations. | Should not be marketed as diagnosing, treating, curing or preventing disease without appropriate regulatory status and clinical framework. |
Medical treatment is defined by the full protocol: intended use, pressure, oxygen dose, exposure duration, patient selection, equipment classification, clinical supervision and applicable regulation.
Monoplace, Multiplace and Room-Style Chambers
Hyperbaric chambers vary in size, pressure capability, oxygen-delivery method, intended use and number of occupants. Understanding these differences matters when comparing equipment.
Monoplace Medical Chamber
Designed for one patient. Traditional clinical monoplace chambers commonly use a transparent cylindrical chamber in which the patient lies down during treatment.
- Single-patient clinical format
- Physician-directed protocols
- Continuous professional monitoring
Multiplace Medical Chamber
Large medical chambers can accommodate two or more people. The chamber is commonly pressurized with air while patients breathe oxygen through masks or clear hoods.
- Multiple patients
- Medical oxygen breathing systems
- Clinical staff may accompany patients
Room-Style Hyperbaric Chamber
Modern room-style designs provide more interior space for sitting or reclining and may be configured for single, companion or multi-user operation.
- Spacious interior layouts
- Different pressure capabilities
- Medical or wellness status depends on configuration and market
Looking for a Hyperbaric Chamber Rather Than Medical Treatment?
Compare Ueerl single-user, two-person, four-person and larger room-style hyperbaric oxygen chamber configurations.
What Happens During a Hyperbaric Oxygen Therapy Session?
The exact process depends on whether the session is medical or wellness-oriented, but the physical pressure cycle generally follows the same basic pattern.
The most noticeable sensation usually occurs while pressure is changing. Your ears may feel full or “pop,” similar to takeoff or landing in an airplane.
Screening & Preparation
For medical HBOT, a healthcare team reviews the indication, relevant medical history, medications, ear and sinus status, implants and other safety considerations.
Pressure Gradually Increases
Chamber pressure rises slowly. Users normally equalize their ears by swallowing, yawning or using an appropriate pressure-equalization technique.
The Main Session
Once the target pressure is reached, the user usually rests, sits or lies comfortably while receiving oxygen according to the selected protocol.
Pressure Returns Gradually
At the end of the session, chamber pressure is gradually reduced toward normal atmospheric pressure.
Assessment or Return to Routine
Clinical facilities may check vital signs, ears or blood glucose when appropriate. Many people can resume normal activities soon after a session.
What Does 1.3, 1.5 or 2.0 ATA Mean?
ATA means atmospheres absolute. It measures total absolute pressure, including the atmospheric pressure already present around us at sea level.
Normal Sea-Level Pressure
Approximately 101.3 kPa absolute pressure.
About 30 kPa Above Atmosphere
Approximately 132 kPa absolute pressure.
About 51 kPa Above Atmosphere
Approximately 152 kPa absolute pressure.
About 101 kPa Above Atmosphere
Approximately 203 kPa absolute pressure.
Some manufacturers list chamber pressure as gauge pressure above the surrounding atmosphere, while medical literature often describes treatment pressure in ATA. Always confirm whether a pressure specification is gauge pressure or absolute pressure before comparing chambers.
What Benefits of HBOT Are Well Established — and What Is Still Being Studied?
One of the biggest sources of confusion online is mixing established clinical indications with early research, wellness outcomes and marketing claims. The evidence is not equally strong for every use.
Selected Recognized Medical Conditions
Strongest clinical acceptance exists for defined hyperbaric medicine indications where pressure and oxygen have a clear therapeutic rationale and established protocols.
- Decompression sickness
- Air or gas embolism
- Carbon monoxide poisoning
- Selected difficult wounds
- Selected radiation tissue injury
- Other recognized hyperbaric indications
Recovery, Aging & Performance Research
Researchers continue to investigate hyperbaric exposure in areas including recovery, cognition, exercise, healthy aging and other applications.
Interesting research does not automatically establish a standard medical indication or guarantee a benefit for an individual user.
Explore Sports Recovery Evidence →Relaxation & Structured Wellness Routines
Home, spa, hotel, fitness and wellness facilities may integrate room-style chambers into broader lifestyle, relaxation or recovery programs.
These services should be described responsibly without presenting general wellness experiences as proven treatment for diseases or medical conditions.
For an evidence-focused discussion of established and unproven HBOT claims, see Harvard Health's independent overview.
Read Harvard Health →
Is Hyperbaric Oxygen Therapy Safe?
HBOT is generally considered safe when appropriately prescribed, operated and monitored, but increased pressure and high oxygen exposure create real risks that should not be ignored.
Pressure changes can cause ear pain, sinus discomfort and, in more significant cases, middle-ear injury.
Repeated clinical treatments can sometimes cause temporary changes in vision.
Enclosed chambers may cause anxiety or discomfort in users who are sensitive to confined spaces.
Excessive oxygen exposure can rarely contribute to central-nervous-system toxicity or seizures.
Serious pressure-related lung injury is uncommon but is a recognized potential complication.
Oxygen-enriched environments require strict control of ignition sources, materials, clothing and prohibited items.
FDA Emphasizes Fire Prevention, Training, Monitoring and Maintenance
In its August 2025 safety communication, the U.S. FDA reminded healthcare providers and facilities to follow each HBOT device's instructions for use, maintain fire-prevention measures, provide proper staff training, monitor patients throughout treatment, and follow recommended cleaning, maintenance and safety checks.
Read the FDA Safety Communication →Hyperbaric Oxygen Is Not Appropriate for Everyone
Medical screening matters because pressure changes, oxygen exposure and the chamber environment can interact with certain medical conditions, medications and implants.
This list is not exhaustive and is not a substitute for medical screening. If you are considering HBOT for a medical condition, discuss suitability, contraindications and treatment protocol with an appropriately qualified healthcare professional.
Does a Hyperbaric Chamber Contain 100% Oxygen?
Not necessarily. The oxygen concentration inside the chamber and the oxygen delivered to the user are two different specifications.
Some Chambers Use an Oxygen Atmosphere
Traditional medical monoplace systems may pressurize the chamber environment with oxygen while the patient lies inside the chamber.
Air-Pressurized Chamber + Oxygen Mask or Hood
In many multiplace medical chambers, the chamber itself is pressurized with air and individual patients breathe oxygen through dedicated masks or hoods.
Oxygen Delivery Depends on Configuration
Room-style chambers may use air pressurization with dedicated oxygen delivery through a cannula, mask, BIBS or another configured breathing system.
On systems that use an oxygen concentrator, a specification such as 93% ±3% normally describes the oxygen generator's output concentration. Chamber atmosphere and user oxygen delivery must be evaluated separately.
Explore Hyperbaric Oxygen Therapy by Application
Once you understand the basics of HBOT, explore how hyperbaric chambers are planned for different wellness, professional and commercial environments.
Treatments & Benefits
Explore HBOT mechanisms, clinical applications, recovery topics and evidence-aware benefit discussions.
Explore Treatments → PRODUCTSHyperbaric Chamber Models
Compare single-user, two-person, four-person and larger room-style chamber configurations.
View All Models → CLINICAL ENVIRONMENTSHyperbaric Chambers for Clinics
Understand clinical planning, supervision, compliance and facility requirements.
Explore Clinic Solutions → HOME WELLNESSHyperbaric Chambers for Private Homes
Explore privacy, space planning, installation and home wellness chamber considerations.
Explore Home Use → RECOVERYSports Recovery & Athletic Performance
Review the research, practical use cases and limitations of hyperbaric oxygen in athlete recovery.
Explore Sports Recovery → SAFETY & QUALITYCertifications & Safety Standards
Review certification documents, quality systems, safety engineering and project compliance.
View Safety Standards → REAL PROJECTSHyperbaric Chamber Installation Cases
See how chamber selection, site planning, installation and commissioning work in real projects.
View Installation Cases → PROJECT SUPPORTPlan a Hyperbaric Chamber Project
Discuss capacity, pressure, intended use, room layout, delivery and installation requirements.
Contact Ueerl →Evidence Sources Used for This Guide
This page is intended to provide clear general education about hyperbaric oxygen therapy. Clinical statements were developed with reference to current information from major medical institutions, professional hyperbaric organizations and U.S. regulatory guidance.
Last reviewed: August 18, 2026
This content is educational and is not a substitute for diagnosis, treatment recommendations or individualized medical advice.
U.S. Food & Drug Administration
Current HBOT device safety guidance, device regulation and facility precautions.
View FDA Source ↗ PROFESSIONAL SOCIETYUndersea & Hyperbaric Medical Society
Professional guidance and recognized hyperbaric oxygen therapy indications.
View UHMS Source ↗ ACADEMIC MEDICAL CENTERMayo Clinic
Overview of HBOT uses, chamber types, preparation, session experience and risks.
View Mayo Clinic ↗ ACADEMIC MEDICAL CENTERJohns Hopkins Medicine
Clinical explanation of HBOT mechanisms, medical uses, chamber types and precautions.
View Johns Hopkins ↗ ACADEMIC MEDICAL CENTERCleveland Clinic
Patient-focused overview of HBOT treatment, medical uses, risks and session expectations.
View Cleveland Clinic ↗ EVIDENCE REVIEWHarvard Health Publishing
Independent discussion of evidence-based applications and unproven HBOT claims.
View Harvard Health ↗Frequently Asked Questions About Hyperbaric Oxygen Therapy
Quick answers to common questions about hyperbaric chambers, treatment pressure, oxygen delivery, safety and medical versus wellness use.
What is hyperbaric oxygen therapy?
What does a hyperbaric chamber do?
How does hyperbaric oxygen therapy work?
How long is an HBOT session?
What does HBOT feel like?
What does 1.5 ATA mean?
What is hyperbaric oxygen therapy used to treat?
Is wellness hyperbaric use the same as medical HBOT?
Does the whole chamber contain 100% oxygen?
Is HBOT safe?
Who should not use a hyperbaric chamber?
Is HBOT proven for anti-aging or sports performance?
Looking for the Right Hyperbaric Chamber?
Tell Ueerl whether your project is for a private home, wellness center, clinic, spa, gym, hotel or commercial facility. Our team can help compare chamber capacity, pressure, oxygen delivery, space requirements, installation and support.
