What Is Ozone Therapy? The Complete Guide

Ozone therapy is the medical use of a small, measured dose of ozone gas (O₃, mixed with pure medical oxygen). It is given into the blood, rectum, vagina, ears, skin, a joint or the mouth, and it is never breathed. The ozone reacts within seconds, and the mild oxidative signal it leaves behind prompts the body's own antioxidant, immune and circulation responses.

This page covers the whole subject in one place. Each section gives the full answer in short form, and the links at the end of each take you to the detailed article or protocol.

Quick answers

• How it works: a small, controlled dose of oxidative stress that the body answers by building up its own defenses, the same principle as exercise (hormesis). Jump
• How it's given: in a clinic (IV ozone, injections, dental) or at home (rectal, vaginal and ear insufflation, ozonated water and oil, limb bagging). Jump
• Best evidence: ozone injections for spinal disc problems and joint pain, chronic wounds and diabetic foot ulcers, dental use and infections it can touch directly. Many other uses rest on smaller studies. Jump
• Safety: complications are rare when established protocols are followed. Never breathe it. Some people shouldn't have it. Jump
• Legal status (US): no federal law bans it, but it isn't FDA approved for any condition. Licensed practitioners use it under their own licenses. Jump
• Cost: about $200 to $300 for a standard IV session, $400 to $4,000 for high-dose IV forms, or about $1,200 to $2,200 one time for a home setup. Jump

Jump to: What it is · How it works · How it's given · Uses and evidence · Safety · Dosing · Cost · Legal and FDA · Get started · FAQ

What is ozone therapy?

Ozone is oxygen with one extra atom. The oxygen you breathe is O₂, two atoms. Ozone is O₃, three. The third atom is loosely attached and reacts with whatever it touches, a process called oxidation. That reactivity makes ozone useful in medicine and is the reason it has to be handled carefully.

Ground-level ozone from pollution really is harmful to breathe, and so is medical ozone, so no form of ozone therapy involves breathing the gas.

Medical ozone vs industrial ozone. Industrial generators run on room air, which is only 21% oxygen, and are often built from parts that break down under ozone and shed contaminants into the gas. That works for purifying water. It doesn't belong in your body. Medical ozone is made from a tank of medical-grade oxygen run through a generator built entirely from ozone-resistant materials. The output is roughly 2-5% ozone and 95-98% oxygen, set to a precise concentration in micrograms per milliliter (µg/mL).

A short history. Medical writing on ozone goes back to at least 1871. During the First World War, Major George Stoker of the Royal Army Medical Corps reported using ozone on infected war wounds [1]. Dr. Velio Bocci at the University of Siena built much of the modern science of how ozone acts in the body from the early 1990s on [2]. Our own count found 2,173 papers since 2000, including 949 clinical studies and 113 randomized trials, rising from 24 papers in 2000 to 189 in 2025 (the research numbers).

[KEEP: the two existing historical images, 1871 German medical yearbook and Stoker 1916]

How does ozone therapy work?

Ozone doesn't travel around your body. When it meets blood or tissue it reacts within seconds with the fats and antioxidants there and is used up at the point of contact. What travels on are the products of those reactions, mainly hydrogen peroxide and lipid oxidation products. Researchers call them messengers [3].

The signal is a small, deliberate stress. A hard workout stresses your muscles, and your body rebuilds them a little stronger. Ozone is thought to work the same way: a small, measured dose of oxidative stress sets off a self-correcting response and leaves stronger defenses. Scientists call this hormesis.

The best-mapped route runs through a protein called Nrf2. When the ozone signal arrives, a sensor protein releases Nrf2, and Nrf2 switches on the genes that build the cell's protective enzymes (superoxide dismutase, catalase, glutathione peroxidase). Ozone gets your body to make more of its own antioxidants.

This has been measured in people. In healthy volunteers, Nrf2 rose as soon as the blood met ozone and was still raised 30 minutes later. By the third session Nrf2 had settled back to normal, while superoxide dismutase and catalase stayed higher than at the start [5]. In multiple sclerosis patients given rectal ozone three times a week for a month, researchers saw the whole chain: more active Nrf2, higher protective enzymes and glutathione, and lower oxidative damage and inflammatory signals [6].

Why dose matters. Because ozone works by hormesis, more is not better. Bocci's group described the effect on blood as a bell curve: too little does nothing, the right range helps, and too much harms [4]. See dosing.

Ozone is often called a biological response modifier: the proposal is that it calms an overreacting immune system and supports an underactive one. Studies in different conditions point both ways, and none has compared both under one protocol.

The five things ozone does in the body

1. It hardens cells against damage. The Nrf2 response above. In a randomized acute stroke trial (62 patients), ozone autohemotherapy raised Nrf2, lowered oxidative damage and improved neurological scores about 30% more than oxygen placebo [7].
2. It calms inflammation and rebalances the immune system. The same pathway turns down the cell's main inflammatory switch. In rheumatoid arthritis (60 patients), adding ozone to methotrexate took pain from 9.2 to 4.7 out of 10, against 8.2 to 7.0 on methotrexate alone [8].
3. It improves blood flow and oxygen delivery. Ozone makes red blood cells more flexible and blood less viscous [9], and in patients with poor circulation it reduced the share of low-oxygen muscle tissue [10].
4. It kills microbes on contact. In the lab, ozone gas at 20 µg/mL for five minutes stopped growth of MRSA, VRE and other resistant bacteria, where oxygen alone did nothing [11].
5. It reshapes the local environment it touches. In diabetic foot ulcers, ozone-treated wounds showed more of the growth factors that drive new blood vessels and tissue, and more collagen [12].

The first three travel through the blood and happen body-wide. The last two only happen where ozone physically touches tissue, which is why the method matters (next section). A useful way to read any ozone study: how it was given → what it did in the body → what changed for the person.

Go deeper: How ozone therapy works · Bio-oxidative therapy and redox medicine

How is ozone therapy given?

Ozone is never breathed. Beyond that, the methods aren't interchangeable. Systemic methods reach the whole body through the blood, either directly (IV ozone) or by absorption (rectal insufflation). Local methods act where they're applied, on skin, in a wound, in the mouth, in the ear or in a joint. The line isn't perfectly clean: rectal insufflation also acts on the colon lining and gut bacteria.

Clinic methods are stronger per session and cost more. Home methods are gentler and can be repeated much more often, which matters because the benefit builds with repeated sessions.

What to know. MAH is the most common IV form worldwide and has the most research behind it. High-dose forms cost much more and have little research comparing them with standard MAH. Injections are the route behind most of the large pain literature, so when you see a claim about ozone and pain, check which route it came from. Dental ozone is the most mainstream-accepted use in medicine. Rectal insufflation is the workhorse of home ozone: the colon wall absorbs the gas within seconds, and sessions cost cents once you own the equipment. Ozone leaves water quickly, so ozonated water has to be made fresh.

Two methods to avoid. Direct IV injection of ozone gas into a vein is a condemned practice. The international ozone therapy bodies reject it because of the risk of gas embolism [13]. If a provider offers it, go elsewhere. Nasal insufflation (gas directly into the nose) is not recommended at home. See our ear, nose and throat article.

Which is best? In the clinic, MAH is the best-studied starting point. At home, rectal and vaginal insufflation lead, and a kit covering rectal, ear and ozonated water handles most needs.

Go deeper: Comparing home therapies · Comparing IV therapies · IV vs rectal · Ozone at home · All protocols

What is ozone therapy used for, and what does the evidence say?

An old saying in the field is "ozone treats many things but cures nothing." It's usually added alongside other care, or used for prevention and recovery.

The evidence is uneven. The Madrid Declaration on Ozone Therapy, the consensus document of the International Scientific Committee of Ozone Therapy (ISCO3), grades each use by the strength of its evidence [13, 14]:

• Level A (good evidence): spinal disc problems.
• Level B (fair evidence): joint and soft-tissue pain (knee arthritis, tendinopathies, carpal tunnel), diabetic foot and chronic wounds, dental cavities, chronic fatigue and fibromyalgia, sudden hearing loss, age-related macular degeneration, poor circulation in the legs, and infections, especially those resistant to antibiotics.
• Level C (expert opinion, small studies, lab work): most everything else, including autoimmune disease, support during cancer treatment, skin conditions, lung, gut, liver and vascular disease.

Level C usually means the large trials haven't been done yet. By use:

Where the evidence is weak or mixed. Ozone put into the bloodstream is used up within seconds and doesn't circulate, so it can't directly sterilize a virus in the body. Any benefit would come through the immune system, and the human evidence is thin. In severe COVID the trials are mixed. Several found shorter hospital or ICU stays, while one 60-patient trial found more transfers to intensive care with ozone (11 of 26) than without (3 of 29), the only controlled ozone study we know of that reports a signal of harm [23].

Why the evidence looks the way it does. Ozone can't be patented, so no company stands to recover the cost of a large trial. Much of the work is small and published in non-English journals that English-language searches rarely surface.

Full condition list: What diseases does ozone therapy treat?

Ozone therapy in athletics

Some well-known athletes have used ozone therapy, mostly for injury recovery:

• Adrian Peterson said he used ozone therapy, among other treatments he paid for himself, while recovering from his 2016 knee injury (Star Tribune; ESPN).
• Cristiano Ronaldo was reported in 2015 to be having ozone therapy sessions for a patellar tendon problem (Managing Madrid).
• UFC fighter Ion Cutelaba declared ozone therapy on his doping control forms in 2017. Because that treatment involved reinfusing blood, a method WADA prohibits without an exemption, he received a six-month sanction (USADA).

What people report

People most often report more energy, wellbeing, endurance, clearer thinking and less pain. These are self-reported, vary a lot, and some people notice nothing. Many notice more energy and less brain fog after 4 to 6 IV sessions or 3 to 4 weeks of regular home sessions. Consistency matters more than any single session.

Is ozone therapy safe? Side effects and contraindications

When it's done with medical-grade equipment, at a measured dose, by someone trained, and never breathed, serious complications are rare.

Never breathe ozone. The lining of your lungs has very little antioxidant protection, so ozone gas irritates and inflames the airways even in small amounts. Blood and most other tissues carry far more antioxidant capacity, so the same molecule can harm the lungs and still be used in a vein. Every method on this page keeps the gas out of the lungs. You will probably smell a little ozone during home sessions. People can smell it at about 0.005 parts per million, well below the level OSHA sets for workplace air, and a ventilated room or fan keeps it down.

How rare are complications? A 1982 survey of German ozone therapists covering millions of treatments found complications were very rare [24]. It's old and self-reported, so treat it as a rough signal. Published reports of serious harm mostly involve practices the field itself condemns, above all injecting ozone gas directly into a vein. At least one death from a gas embolism during ozone autohemotherapy is documented in a medical journal [25]. Our safety article covers the reported harms.

Common side effects

Most side effects are mild, short-lived and depend on the method:

• Herxheimer reaction: flu-like symptoms, fatigue, rash, chills or swollen lymph nodes after the first few sessions, thought to come from the immune response and from microbes dying off quickly. It's the main reason ozone starts low and builds slowly.
• After IV ozone: tiredness, headache or achiness. Bruising at the needle site.
• Rectal: cramping or bloating, usually from too much gas or too strong a dose. Mucus in the stool can mean the dose is too strong.
• Ear and water: ear itching, dryness or headache, and a scratchy throat or headache with ozonated water.
• Accidental inhalation: coughing and chest discomfort.

If a reaction happens, the protocols say to stop for 4 to 7 days, then restart at half the dose and time and work back up slowly with your practitioner. More detail: Herxheimer reactions and ozone therapy.

Contraindications (reasons to avoid ozone therapy)

From our clinic protocol guide, the main reasons not to have ozone therapy are:

• Pregnancy
• Allergy to heparin (used in the IV protocol)
• Toxic hyperthyroidism (severe Graves' disease)
• Very low platelets or severe clotting disorders
• Recent heart attack, severe heart instability, or heart disease that hasn't been reviewed with a physician
• Acute heavy bleeding, acute alcohol intoxication, or seizure states
• Currently receiving IV copper or iron therapy
• Breathing ozone gas directly, ever

G6PD deficiency (favism) is a consideration for standard IV ozone (MaH), since it means lower antioxidant capacity: the practitioner starts low, follows the titration and monitors. It is an absolute contraindication for 10-Pass, EBOO and HiDose. Some other conditions are also considerations rather than absolute no's: blood thinners, and high or low blood pressure. With blood pressure, a physician should review your medications first, because heparin is used in the IV (MaH) protocol. The full list is in our IV ozone protocol and our safety article.

The honest downsides

It doesn't always work, and testimonials come from the people it worked for. It costs money, takes weeks, and good providers can be hard to find. For many uses the evidence is thinner than enthusiasts claim, and we've marked where above.

Ozone therapy dosing basics

Educational summary for practitioners and supervised home users. Dosing should be set with a qualified practitioner.

Concentration. Dose starts with concentration, measured in micrograms of ozone per milliliter of gas (µg/mL). Practitioners call this "gamma". The total dose is concentration × volume. For example, 30 µg/mL × 200 mL = 6,000 µg (6 mg). See how to calculate a dose of ozone.

The window. The Madrid Declaration sets 80 µg/mL as the upper limit for ozone in contact with blood. At or above that level, ozone starts damaging red blood cells and blocks the very protective response the therapy is meant to switch on [13]. Our clinic IV protocol tops out at 70.

Typical ranges from our protocols:

Start low, go slow. Every protocol starts at the low end and builds up as you tolerate it. On IV ozone, practitioners raise the dose 5-10 µg/mL per session after a good or neutral response and lower it after fatigue, headache or a Herxheimer reaction. Don't do an IV and a rectal session on the same day.

Frequency matters as much as strength. One session produces a brief spike of oxidative stress, then recovery to a level above where you started (the Nrf2 time course above is the measured version [5]). The proposal is that repeating sessions at the right spacing lets the gain build, while sessions too far apart fade and sessions too close together can overshoot. The best spacing hasn't been pinned down in trials. That is the case for home methods on long courses.

How much does ozone therapy cost?

Prices vary by clinic and region, and insurance rarely covers ozone therapy. One MAH session a week comes to $10,400 to $15,600 a year, while a home setup usually pays for itself within a few months and handles rectal, vaginal and ear insufflation, ozonated water and limb bagging. Compare total course costs, not per-session prices. Generators under about $200 are usually air purifiers and aren't made for therapy.

Go deeper: IV vs rectal ozone (cost breakdown) · Comparing IV ozone therapies · Choosing a home ozone machine · Why a cheap machine is a false economy · Oxygen for ozone therapy

Is ozone therapy legal? FDA status

In the US, yes. No federal law bans ozone therapy. It isn't FDA approved for any condition, and no ozone device has been FDA cleared for giving ozone to people. Licensed practitioners use it under their own licenses, and rules differ by state.

The FDA "toxic gas" statement. The federal rule you'll see quoted (21 CFR 801.415, from 1976) calls ozone "a toxic gas with no known useful medical application" [26]. That rule covers breathing ozone and devices that release ozone into room air. It doesn't address whether a licensed clinician may use ozone. The FDA regulates products, and state boards regulate practitioners.

Why it isn't FDA approved. Approval takes large, expensive trials, and ozone can't be patented. The closest ozone has come was Vasogen, whose ozone-based blood treatment reached a phase III trial, missed its main goal and was never approved.

Outside the US. Ozone therapy is used in clinics and hospitals across much of Europe, in Cuba and Russia, and elsewhere, under each country's rules. The Madrid Declaration, a consensus of ozone therapy associations from many countries, sets out the doses and methods those practitioners follow [13]. Generators sold in the EU carry a CE mark, which covers device safety and manufacturing and isn't an approval of ozone therapy for any disease.

Go deeper: Is ozone therapy legal? The FDA "toxic gas" statement, explained

Next steps

Start with a doctor: go through the contraindications above, your medications and what you want from it. For a clinic, use our find a provider page (see what ozone therapy costs first) and ask what concentration and volume they use, whether they use medical-grade oxygen and an ozone-resistant generator, which protocol they follow (the Madrid Declaration and published MAH protocols are good answers), whether they ever inject ozone gas directly into a vein (the right answer is no), and how they screen for contraindications and handle reactions. For home use you need a medical-grade generator, medical oxygen with a regulator, accessories for your method and its protocol, followed from the low end. Many people do both, never on the same day.

If you're a practitioner: our free live IV Ozone 101 training covers MAH from equipment to titration, using the IV protocol we train on.

If you're a home user: our free home ozone guide covers choosing equipment, getting oxygen, setting up and the starting protocols. Get the free guide

You can also browse the protocols directly or start with ozone at home.

Frequently asked questions

What is ozone therapy?

The medical use of a small, measured dose of ozone gas mixed with pure oxygen, never breathed. More

How does it work?

The body answers a mild oxidative signal by building its own defenses. More

What is it used for?

Best evidence: disc and joint pain injections, chronic wounds, dental use. More

Is it safe?

Serious complications are rare with the right equipment, dose and provider. More

Is it FDA approved?

No, but no federal law bans it. More

How much does it cost?

About $200 to $300 per IV session, or $1,200 to $2,200 for a home setup. More

Can you do it at home?

Yes, except IV ozone and injections. More · Free guide

None of the information on this page is intended to treat, cure, or diagnose any condition. MediSkill exists for informational purposes only and is not a substitute for medical advice. Always consult your medical practitioner.

References

1. Stoker G. The surgical uses of ozone. The Lancet. 1916. (Primary source; existing page image.)
2. Bocci VA. Scientific and medical aspects of ozone therapy. State of the art. Arch Med Res. 2006;37(4):425-435. doi:10.1016/j.arcmed.2005.08.006
3. Sagai M, Bocci V. Mechanisms of action involved in ozone therapy: is healing induced via a mild oxidative stress? Med Gas Res. 2011;1:29. doi:10.1186/2045-9912-1-29
4. Bocci VA, Zanardi I, Travagli V. Ozone acting on human blood yields a hormetic dose-response relationship. J Transl Med. 2011;9:66. doi:10.1186/1479-5876-9-66
5. Re L, Martínez-Sánchez G, Bordicchia M, et al. Is ozone pre-conditioning effect linked to Nrf2/EpRE activation pathway in vivo? A preliminary result. Eur J Pharmacol. 2014;742:158-162. doi:10.1016/j.ejphar.2014.08.029
6. Delgado-Roche L, Riera-Romo M, Mesta F, et al. Medical ozone promotes Nrf2 phosphorylation reducing oxidative stress and pro-inflammatory cytokines in multiple sclerosis patients. Eur J Pharmacol. 2017;811:148-154. doi:10.1016/j.ejphar.2017.06.017 (MS immune-cell shift: Hernández-Matos Y, et al. Mult Scler Relat Disord. 2020. doi:10.1016/j.msard.2020.102466)
7. Cheng H, Lu R, Du J, Zhao X, Zhuang Z. A clinical study on ozone autohemotherapy for the treatment of acute ischemic stroke. Front Med. 2025;12:1595568. doi:10.3389/fmed.2025.1595568
8. León Fernández OS, et al. Medical ozone increases methotrexate clinical response and improves cellular redox balance in patients with rheumatoid arthritis. Eur J Pharmacol. 2016. doi:10.1016/j.ejphar.2016.07.031
9. Giunta R, Coppola A, Luongo C, et al. Ozonized autohemotransfusion improves hemorheological parameters and oxygen delivery to tissues in patients with peripheral occlusive arterial disease. Ann Hematol. 2001;80:745-748. doi:10.1007/s002770100377
10. Clavo B, Pérez JL, López L, et al. Effect of ozone therapy on muscle oxygenation. J Altern Complement Med. 2003;9(2):251-256. doi:10.1089/10755530360623365
11. Fontes B, et al. Effect of low-dose gaseous ozone on pathogenic bacteria. BMC Infect Dis. 2012;12:358. doi:10.1186/1471-2334-12-358
12. Zhang J, Guan M, Xie C, et al. Increased growth factors play a role in wound healing promoted by noninvasive oxygen-ozone therapy in diabetic patients with foot ulcers. Oxid Med Cell Longev. 2014;2014:273475. doi:10.1155/2014/273475
13. International Scientific Committee of Ozone Therapy (ISCO3). Madrid Declaration on Ozone Therapy, 4th ed. 2025. (80 µg/mL upper limit; inhalation contraindicated; direct IV gas injection condemned.)
14. ISCO3. Madrid Declaration on Ozone Therapy, 3rd ed. 2020. (Level A/B/C evidence grading, as used on our what-diseases page.)
15. Arjmanddoust Z, et al. Efficacy of two doses of intra-articular ozone therapy for pain and functional mobility in knee osteoarthritis. Adv Rheumatol. 2025. doi:10.1186/s42358-025-00443-w
16. Wainstein J, Feldbrin Z, Boaz M, Harman-Boehm I. Efficacy of ozone-oxygen therapy for the treatment of diabetic foot ulcers. Diabetes Technol Ther. 2011;13(12):1255-1260. doi:10.1089/dia.2011.0018
17. Pardo A, et al. Effectiveness of ozone therapy in non-surgical periodontal treatment: a meta-analysis. J Clin Med. 2025;14(14):5124. doi:10.3390/jcm14145124
18. Kist S, Kollmuss M, Jung J, et al. Comparison of ozone gas and sodium hypochlorite/chlorhexidine two-visit disinfection protocols in treating apical periodontitis: a randomized controlled clinical trial. Clin Oral Investig. 2017;21(3):995-1005. doi:10.1007/s00784-016-1849-5
19. Tara F, Zand-Kargar Z, Rajabi O, Berenji F, Azizi H. The effects of ozonated olive oil and clotrimazole cream for treatment of vulvovaginal candidiasis. Altern Ther Health Med. 2016;22(4):44-49. PMID 27548492
20. Menéndez Cepero SA, et al. Systemic ozone therapy by rectal insufflation for immunoglobulin A deficiency. MEDICC Review. 2018;20(1). doi:10.37757/mr2018.v20.n1.7
21. Hou Q, et al. Clinical trial of ozonated water enema for the treatment of fibromyalgia: a randomized, double-blind trial. Pain Physician. 2025;28(1). PMID 39903016
22. Turan M. Doping that is not a doping: effects of ozone therapy in sportsmen. J Ozone Ther. 2021. doi:10.7203/jo3t.5.6.2021.21386
23. Salmanzadeh S, Sheibani B, Bitaraf S, Nashibi R, Moogahi S. Therapeutic efficacy of ozonated blood in severe COVID-19 patients: a randomized controlled trial. Front Med. 2025;12:1546767. doi:10.3389/fmed.2025.1546767
24. World Federation of Ozone Therapy (WFOT) Scientific Advisory Committee. WFOT's Review on Evidence-Based Ozone Therapy. 2015. (Reports the Jacobs 1982 German survey.)
25. Marchetti D, La Monaca G. An unexpected death during oxygen-ozone therapy. Am J Forensic Med Pathol. 2000;21(2):144-147. doi:10.1097/00000433-200006000-00010
26. US FDA. 21 CFR 801.415, Maximum acceptable level of ozone. https://www.ecfr.gov/current/title-21/chapter-I/subchapter-H/part-801/subpart-H/section-801.415