Oxygen Therapy: Types, Uses, and What the Evidence Shows

Oxygen therapy is any treatment that delivers extra oxygen to your body to support healing, relieve symptoms, or sustain life. It ranges from the supplemental oxygen flowing through a nasal cannula in a hospital bed to pressurized chambers that push oxygen deep into damaged tissues. More than 1.5 million Americans use long-term oxygen therapy at home, and the medical applications keep expanding as researchers discover new ways concentrated oxygen can help the body repair itself.¹

This guide covers every major form of oxygen therapy, what the clinical evidence actually shows, who benefits most, and what it costs.

What Is Oxygen Therapy?

Oxygen therapy is the medical use of supplemental oxygen to treat conditions where the body cannot get enough on its own. Normal air contains about 21% oxygen. Oxygen therapy increases that concentration, sometimes to 100% medical-grade oxygen, to raise blood oxygen levels and support tissue function.

Your body depends on oxygen for every cellular process. Red blood cells pick up oxygen in the lungs and carry it to tissues throughout the body. When disease, injury, or altitude reduces the oxygen supply, cells begin to struggle. Organs start to malfunction. At severe levels, oxygen deprivation becomes life-threatening within minutes.

Physicians prescribe oxygen therapy for two broad purposes. The first is life support: keeping blood oxygen levels high enough to sustain organ function in patients with chronic lung disease, acute respiratory failure, or post-surgical recovery. The second is therapeutic: using concentrated or pressurized oxygen to accelerate healing, reduce inflammation, or fight infection in damaged tissues.

“Continuous oxygen therapy reduced mortality by 52% compared to nocturnal-only oxygen over 19 months.”
Nocturnal Oxygen Therapy Trial Group, 1980

Types of Oxygen Therapy

Not all oxygen therapy works the same way. The delivery method, pressure, and concentration vary widely depending on the clinical goal. Here is how the major types compare.

Type	How It Works	Oxygen Level	Typical Use
Supplemental Oxygen	Nasal cannula, face mask, or ventilator delivers extra O2	24-100%	COPD, pneumonia, heart failure, post-surgery
Hyperbaric (HBOT)	100% O2 in a pressurized chamber (1.5-3.0 ATA)	100%	Wound healing, CO poisoning, decompression sickness
EWOT	Breathing concentrated O2 during exercise	90-95%	Athletic performance, anti-aging, circulation
Topical Oxygen	Oxygen applied directly to wound surface	100%	Diabetic foot ulcers, chronic wounds
Ozone Therapy	Medical ozone (O3) administered via IV, injection, or insufflation	O3/O2 mix	Immune support, chronic infections, pain
Normobaric Oxygen	100% O2 at normal atmospheric pressure via mask	100%	Cluster headaches, acute carbon monoxide exposure
Oxygen Bars/Facials	Brief sessions of scented or concentrated oxygen	40-90%	Relaxation, cosmetic (no proven medical benefit)

Supplemental (Medical) Oxygen

This is the most common form of oxygen therapy worldwide. A physician prescribes a specific flow rate (measured in liters per minute), and the patient receives it through a nasal cannula (small prongs in the nostrils), a simple face mask, a non-rebreather mask, or in critical cases, a mechanical ventilator.

The oxygen source can be a compressed gas cylinder, a liquid oxygen tank, or an oxygen concentrator that filters nitrogen from room air. Home concentrators have become the standard for long-term therapy because they never run out and are relatively affordable to operate.

Medicare and most private insurers cover supplemental oxygen when a patient’s arterial oxygen saturation drops to 88% or below (or PaO2 of 55 mmHg or less) at rest.⁴ The qualifying test is a resting arterial blood gas or pulse oximetry reading taken during a stable clinical state.

Hyperbaric Oxygen Therapy (HBOT)

Hyperbaric oxygen therapy places the patient inside a sealed chamber pressurized to 1.5 to 3.0 times normal atmospheric pressure while breathing 100% medical-grade oxygen. The increased pressure forces far more oxygen into the blood plasma than breathing alone can achieve. According to Henry’s Law, the amount of gas dissolved in a liquid is directly proportional to the pressure of that gas above the liquid.

At 2.0 ATA (the most common treatment pressure), blood plasma carries roughly 10 times more dissolved oxygen than at sea level.⁶ This oxygen-rich plasma can reach tissues that damaged or blocked blood vessels cannot supply through normal red blood cell delivery.

The FDA has cleared HBOT for 14 conditions, including decompression sickness, carbon monoxide poisoning, gas gangrene, crush injuries, diabetic foot ulcers, radiation tissue damage, and compromised skin grafts.³ Research into off-label uses like traumatic brain injury, stroke recovery, and Long COVID is ongoing but not yet FDA-approved. If you want a deeper look at how chambers work and what the research shows, our complete guide to hyperbaric chambers covers everything in detail.

Exercise with Oxygen Therapy (EWOT)

EWOT involves breathing high-concentration oxygen (90-95%) through a mask while exercising, typically on a stationary bike or treadmill, for 15 to 20 minutes. The concept traces back to German physicist Manfred von Ardenne, who developed what he called “oxygen multistep therapy” in the 1970s.⁷

Von Ardenne’s research proposed that combining exercise (which increases cardiac output and opens capillaries) with concentrated oxygen would dramatically improve tissue oxygenation, particularly in areas with compromised microcirculation. His published work showed improvements in blood flow and oxygen utilization in older adults.

EWOT has a following in wellness and anti-aging circles, but it lacks the robust clinical trial evidence that supports supplemental oxygen for COPD or HBOT for wound healing. Most evidence remains observational or from small studies. It is not FDA-cleared for any medical condition and is not covered by insurance.

Topical Oxygen Therapy

Topical oxygen therapy delivers oxygen directly to the surface of a wound rather than through the lungs and bloodstream. The most common approach uses a small, portable device that creates an oxygen-enriched environment around the wound using a sealed dressing or chamber placed over the affected area.

The rationale is straightforward: chronic wounds often have severely reduced local oxygen levels because of damaged blood vessels in the surrounding tissue. Delivering oxygen directly to the wound site bypasses the circulatory bottleneck. A 2020 systematic review by Thanigaimani et al. found that topical oxygen therapy significantly improved healing rates in diabetic foot ulcers compared to standard wound care alone.⁵

The FDA has cleared several topical oxygen devices for wound management. Unlike HBOT, topical oxygen can be applied at home and does not require a pressurized chamber. It is often used when patients cannot access or tolerate HBOT sessions.

Ozone Therapy

Ozone therapy uses medical-grade ozone (O3), a molecule made of three oxygen atoms, delivered through various routes including intravenous infusion (major autohemotherapy), injection into joints, rectal or vaginal insufflation, or topical application. Proponents argue that ozone triggers a controlled oxidative stress response that stimulates the immune system and improves oxygen utilization at the cellular level.

Ozone therapy is widely practiced in Europe and Latin America and is gaining traction in the US, primarily through integrative and regenerative medicine clinics. It is not FDA-approved in the United States, and the FDA has explicitly stated that ozone has “no known useful medical application.”⁸ Despite this, published research exists. Bocci et al. (2011) outlined the biochemical mechanisms and Clavo et al. (2018) reviewed its use in cancer as a complementary approach.⁹¹⁰ For a detailed comparison with other oxygen-based treatments, see our breakdown of HBOT vs. ozone therapy vs. IV NAD.

Normobaric Oxygen Therapy

Normobaric oxygen therapy means breathing 100% medical-grade oxygen at normal atmospheric pressure (1.0 ATA), typically through a tight-fitting non-rebreather mask. It sits between standard supplemental oxygen (which often delivers 24-60% concentration) and hyperbaric oxygen (which uses pressure above 1.0 ATA).

The best-established use is for acute cluster headache attacks. A randomized controlled trial by Cohen et al. (2009) found that inhaling 100% oxygen at 12 liters per minute provided pain relief in 78% of cluster headache episodes within 15 minutes, compared to 20% with room air.¹¹ It is also the standard first-line treatment for acute carbon monoxide poisoning when a hyperbaric chamber is not immediately available.

Oxygen Bars and Oxygen Facials

Oxygen bars offer brief sessions (typically 10-20 minutes) of breathing flavored or scented oxygen at concentrations around 40-90%. They are found in spas, airports, and wellness centers. Oxygen facials spray pressurized oxygen onto the skin, sometimes mixed with serums.

Neither has any proven medical benefit. The American Lung Association has noted that healthy individuals do not benefit from supplemental oxygen, and short sessions at a bar or spa cannot meaningfully change blood oxygen levels in someone whose levels are already normal.¹² These are recreational experiences, not therapies.

Medical Conditions Treated with Oxygen Therapy

Oxygen therapy is a standard treatment across dozens of medical conditions. Here are the most common and well-supported applications.

Chronic Obstructive Pulmonary Disease (COPD)

COPD is the single largest reason people use long-term oxygen therapy. When COPD progresses to the point where blood oxygen levels drop chronically below safe thresholds, supplemental oxygen becomes a lifeline.

Two landmark trials established the survival benefit. The Nocturnal Oxygen Therapy Trial (NOTT) in 1980 compared continuous oxygen (at least 19 hours/day) with nocturnal-only oxygen (12 hours/day) in 203 COPD patients. The continuous group had 52% lower mortality over 19 months.² The British Medical Research Council (MRC) trial in 1981 compared oxygen (at least 15 hours/day) with no oxygen in 87 patients and found a significant survival advantage in the oxygen group over five years.¹³

The current GOLD 2024 guidelines recommend long-term oxygen therapy for stable COPD patients with a resting PaO2 at or below 55 mmHg (or SpO2 at or below 88%).¹⁴ HBOT has also been explored for COPD, and you can read about that research in our article on hyperbaric chambers for COPD.

Pneumonia and Acute Respiratory Failure

Supplemental oxygen is a cornerstone of treatment for pneumonia, acute respiratory distress syndrome (ARDS), and other conditions that acutely impair gas exchange. In hospitals, oxygen delivery ranges from low-flow nasal cannula to high-flow nasal therapy to mechanical ventilation, depending on severity.

Carbon Monoxide Poisoning

Carbon monoxide binds to hemoglobin with 200 to 250 times the affinity of oxygen, displacing oxygen from red blood cells. Breathing 100% medical-grade oxygen at normobaric or hyperbaric pressure accelerates CO clearance from the blood. The half-life of carboxyhemoglobin drops from 4-6 hours on room air to about 60-90 minutes on 100% normobaric oxygen, and to 15-23 minutes under hyperbaric conditions.¹⁵

Wound Healing

Oxygen is essential for collagen synthesis, angiogenesis (new blood vessel growth), and the oxidative killing of bacteria by white blood cells. When wounds are hypoxic, healing stalls. Both HBOT and topical oxygen therapy address this by raising local oxygen levels. HBOT is FDA-cleared for diabetic foot ulcers, compromised grafts, and chronic refractory osteomyelitis. Topical oxygen offers a more accessible alternative for wounds that have not responded to standard care.

Cluster Headaches

High-flow normobaric oxygen (100% at 12-15 L/min for 15-20 minutes) is one of the two first-line acute treatments for cluster headache, alongside sumatriptan injection. The response rate exceeds 75% in most studies, and it has essentially no side effects.¹¹

Stroke Recovery

Research on HBOT for stroke recovery has shown mixed results. A 2014 trial by Efrati et al. demonstrated neurological improvements in post-stroke patients treated with HBOT even 6 to 36 months after the event, with improvements in brain activity confirmed by SPECT imaging.¹⁶ Larger confirmatory trials are still needed. This remains an off-label application.

Home Oxygen Therapy

About 1.5 million Americans use supplemental oxygen at home.¹ Home oxygen therapy requires a prescription and a qualifying diagnosis, most commonly COPD, interstitial lung disease, pulmonary hypertension, or cystic fibrosis.

Equipment Options

Oxygen concentrators (stationary): These plug into a wall outlet and filter nitrogen from room air, producing oxygen continuously at flow rates of 1-10 liters per minute. They are the most cost-effective option for home use and never need refilling. Models like the Invacare Platinum 10 or Philips Respironics EverFlo are common.

Portable oxygen concentrators (POCs): Battery-powered units weighing 3-10 pounds that allow mobility. Most deliver oxygen in pulse-dose mode (a burst on inhalation) rather than continuous flow. Popular models include the Inogen One G5 and the CAIRE FreeStyle Comfort.

Compressed gas cylinders: Traditional green tanks that contain gaseous oxygen under pressure. They are reliable but heavy (the standard E-cylinder weighs about 8 pounds) and need regular refilling or exchange.

Liquid oxygen systems: Store oxygen in liquid form at extremely cold temperatures. A large stationary reservoir at home feeds a small portable unit the patient carries. They hold more oxygen per volume than gas cylinders but are less common now that POCs have improved.

Prescription Requirements

In the United States, supplemental oxygen is a prescription medical device. To qualify for Medicare coverage, a patient must have:⁴

• A qualifying blood oxygen test (SpO2 of 88% or below, or PaO2 of 55 mmHg or below at rest)
• A face-to-face evaluation with their treating physician
• Documentation of the underlying condition causing hypoxemia
• A Certificate of Medical Necessity completed by the physician

Private insurers generally follow similar criteria. Without a qualifying diagnosis, you can still purchase a portable oxygen concentrator out of pocket, but medical-grade stationary systems and liquid oxygen require a prescription.

How Oxygen Therapy Works: The Physiology

Understanding why oxygen therapy works requires a quick look at how your body transports and uses oxygen.

Under normal conditions, about 98.5% of oxygen in your blood travels bound to hemoglobin inside red blood cells. The remaining 1.5% dissolves directly in blood plasma. At sea level, breathing room air (21% oxygen), arterial blood carries roughly 0.3 mL of dissolved oxygen per deciliter of blood.

Here is where Henry’s Law becomes relevant: the amount of gas dissolved in a liquid is directly proportional to the partial pressure of that gas above the liquid. Breathing 100% oxygen at 1.0 ATA raises dissolved plasma oxygen to about 1.5 mL/dL. At 2.0 ATA (standard HBOT pressure), dissolved oxygen reaches approximately 3.0 mL/dL. At 3.0 ATA, it can reach 6.0 mL/dL.⁶

This dissolved oxygen is clinically significant because it does not require hemoglobin or red blood cells for delivery. It can reach tissues through plasma alone, bypassing blockages in small blood vessels, damaged capillaries, or areas of swelling that red blood cells cannot penetrate.

At the cellular level, oxygen drives the mitochondrial electron transport chain, the process that generates ATP (the cell’s energy currency). Hypoxic cells cannot produce enough ATP to maintain normal function, repair damage, or fight infection. Restoring oxygen supply reactivates these processes. Oxygen also stimulates growth factor release (including vascular endothelial growth factor, which triggers new blood vessel formation) and enhances the ability of white blood cells to kill bacteria through oxidative burst mechanisms.¹⁷

Side Effects and Safety

Oxygen therapy is generally safe when used as prescribed, but every form carries some risks.

Supplemental oxygen: The main risk is oxygen toxicity from prolonged exposure to high concentrations. Breathing more than 60% oxygen for extended periods can damage lung tissue, causing tracheobronchitis and eventually pulmonary fibrosis.¹⁸ In COPD patients, excessive oxygen can suppress the hypoxic respiratory drive and cause CO2 retention (hypercapnia). Nasal dryness, skin irritation from the cannula, and nosebleeds are common minor side effects.

HBOT: The most common side effect is barotrauma, particularly middle ear pain or sinus pressure during pressurization. Temporary myopia (nearsightedness) can occur with repeated sessions and usually reverses within weeks of stopping treatment. Oxygen toxicity seizures are rare (estimated at 1-2 per 10,000 treatments) and resolve when oxygen delivery stops.¹⁹

Fire risk: Oxygen itself does not burn, but it accelerates combustion. Any environment with concentrated oxygen has an elevated fire risk. Patients using home oxygen should keep equipment away from open flames, avoid petroleum-based products near the face, and never smoke while on oxygen. Smoking while using supplemental oxygen causes an estimated 182 home oxygen fire deaths per year in the United States.²⁰

Ozone therapy: Side effects can include temporary coughing, chest tightness, and shortness of breath if ozone is inadvertently inhaled. Improperly administered IV ozone can cause air embolism. Because it is not FDA-regulated, quality control varies significantly between practitioners.

For a detailed look at HBOT-specific risks and insurance considerations, see our guide on hyperbaric oxygen therapy insurance.

Cost Overview

The cost of oxygen therapy varies enormously depending on the type, whether you rent or buy equipment, and insurance coverage.

Type	Typical Cost	Insurance Coverage
Home concentrator (stationary)	$300-800 to buy; $100-300/month to rent	Medicare/most insurers cover with qualifying diagnosis
Portable oxygen concentrator	$1,500-3,500 to buy; $200-400/month to rent	Often covered; may require prior authorization
HBOT (clinical, per session)	$200-400/session (40 sessions typical)	Covered for FDA-cleared indications only
HBOT (home chamber)	$4,000-20,000 (mild, 1.3-1.5 ATA)	Not covered
EWOT system	$2,000-5,000 (home setup)	Not covered
Topical oxygen (per treatment cycle)	$500-2,000 for device + dressings	Some insurers cover for diabetic wounds
Ozone therapy (per session)	$100-350/session	Not covered
Oxygen bar session	$15-50 per session	Not covered (recreational)

Frequently Asked Questions

Can you do oxygen therapy at home?

Yes. Millions of Americans use home oxygen concentrators daily. Stationary concentrators plug into a wall outlet and produce oxygen continuously. Portable concentrators run on batteries for use outside the home. Both require a prescription for medical use. Home HBOT chambers (mild, 1.3-1.5 ATA) are also available for purchase without a prescription but operate at much lower pressures than clinical units.

What is the difference between oxygen therapy and hyperbaric oxygen therapy?

Standard oxygen therapy delivers supplemental oxygen at normal atmospheric pressure (1.0 ATA), usually at concentrations of 24-100%. Hyperbaric oxygen therapy delivers 100% medical-grade oxygen at elevated pressure (1.5-3.0 ATA) inside a sealed chamber. The pressure is the key difference: it forces dramatically more oxygen into blood plasma, reaching tissues that supplemental oxygen at normal pressure cannot.

Is oxygen therapy safe for elderly patients?

Oxygen therapy is widely used in elderly patients and is considered safe when prescribed and monitored properly. The main concern is over-oxygenation in patients with COPD, which can suppress breathing drive. Physicians set specific flow rates and monitor blood oxygen levels to keep them in a safe range (typically SpO2 of 88-92% for COPD patients).

How long do you need to be on oxygen therapy?

That depends entirely on the condition. COPD patients may use supplemental oxygen for life, typically 15+ hours per day. HBOT protocols usually run 20-40 sessions over several weeks. Acute conditions like pneumonia or carbon monoxide poisoning require oxygen only until the crisis resolves. Your physician determines duration based on your blood oxygen levels and underlying diagnosis.

Does oxygen therapy help with COVID and Long COVID?

Supplemental oxygen is standard treatment for acute COVID-19 when blood oxygen drops below safe levels. For Long COVID, research is ongoing. A 2022 randomized controlled trial by Zilberman-Itskovich et al. found that HBOT improved cognitive function, fatigue, and brain perfusion in Long COVID patients.²¹ This is promising but still considered experimental and not yet standard of care.

Are there any natural alternatives to oxygen therapy?

For healthy individuals looking to improve oxygen delivery to tissues, cardiovascular exercise is the most effective approach. Regular aerobic exercise increases red blood cell production, improves capillary density, and enhances mitochondrial efficiency. Breathing exercises can improve respiratory muscle strength. However, for patients with genuine hypoxemia from lung disease or other conditions, there is no substitute for supplemental oxygen.

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