Ozone Therapy and the Gut Microbiome: What the Research Shows

Gut health is one of the most common reasons people ask us about ozone therapy. The questions are usually specific: does ozone help with SIBO? What about H. pylori? Will it wipe out my good bacteria along with the bad? Is drinking ozonated water any use, or does it have to be rectal insufflation?

Those are fair questions and they deserve straight answers. This article sets out what the published research shows about ozone and the gut microbiome, what practitioners report from clinical experience, and where formal trials have not yet caught up. Where we link to a study, the write-up includes its design, its numbers and its limitations, so you can judge it rather than take our word for it.

Ozonated drinking water - the route used in the H. pylori trial - is made fresh at home and drunk immediately.

Each figure is explained, sourced and caveated in the sections below.

Why the gut microbiome comes up in ozone conversations

The gut microbiome is the population of bacteria, fungi and other organisms living in your digestive tract. The balance between helpful organisms and less helpful ones - and the shift away from that balance, known as dysbiosis - is now linked to conditions ranging from irritable bowel syndrome to inflammatory bowel disease.

Conventional approaches to dysbiosis include probiotics, prebiotics, antimicrobials and dietary change, with mixed results. That gap is what has driven interest in other options.

The proposal behind ozone is that it is selectively antimicrobial. Ozone is a potent oxidant, and the argument runs that organisms with weaker antioxidant defences - many pathogenic bacteria, and yeasts such as Candida - are more vulnerable to it than the organisms you want to keep. Many problem organisms in the gut are also anaerobes, thriving in low-oxygen conditions, which is why an oxygen-rich, oxidative environment is proposed to tip the balance against them. The research below is the test of whether that holds up in practice - and so far, the direction of the findings has been encouraging.

Ozone and gut bacteria: the human evidence

The most directly relevant study is a 2018 randomised study of 48 adults with constipation-predominant IBS carried out at Dagestan State Medical University in Russia. All participants received standard drug treatment and interference therapy; 28 of them also received ozonated distilled water three times daily for three weeks, plus eight rectal insufflations.

Stool culture at the start and end found that bifidobacteria and lactobacilli - the organisms you want more of - increased in 73.7% of the ozone group, against roughly 47% of controls. Candida cleared in five of the six ozone-group patients who had it. Haemolysing E. coli fell in 84.6% of the ozone group against 50% of controls. On X-ray, bowel transit improved in 89.5% of the ozone group against 60.5% of controls, and quality of life scores were significantly higher.

This directly addresses the most common worry we hear - "will it kill my good bacteria too?" In this study, the answer was no: the beneficial organisms increased while the problematic ones declined, which is exactly what the selective-antimicrobial rationale predicts.

It is one small single-centre study, unblinded, with both ozone routes given together - our full write-up sets out the caveats - but it is a randomised human study, its findings point clearly in ozone's favour, and nothing published contradicts it.

New supporting evidence from microbiome sequencing

A 2025 study using modern 16S rRNA gene sequencing adds independent support from a different direction. Mice fed a high-fat diet to induce atherosclerosis received rectal ozone insufflation every other day, and their gut microbiome was mapped by genetic sequencing rather than culture. Ozone corrected the microbial imbalance caused by the diet - and notably increased Lactobacillus and Bifidobacterium, the same beneficial genera that improved in the human IBS study.

This is an animal study, and its main focus was cardiovascular. But two studies from different countries, using different methods in different species, finding that rectal ozone shifts the microbiome towards beneficial organisms rather than away from them, is the kind of convergence that makes a finding more believable.

H. pylori: the best-designed study we have

Helicobacter pylori is the bacterium behind most stomach and duodenal ulcers. Eradication rates with standard antibiotic therapy have been falling as antibiotic resistance rises, which is why adjuncts are of interest.

A randomised controlled trial of 132 patients tested ozonated tri-distilled drinking water alongside standard therapy, and reported eradication rates of 94-97% along with improved healing of duodenal ulcer lesions - a meaningful lift over standard therapy alone, achieved simply by adding ozonated water.

The trial tested ozonated water added to conventional treatment rather than as a replacement, so that combination is what the 94-97% figure describes. Untreated H. pylori is classified as a carcinogen and eradication should be confirmed by testing, so this is one to pursue with your doctor rather than instead of them.

Gut inflammation and immunity

Two further studies approach the gut from the immune side, and both reported positive results.

A 2022 study in 64 rats with experimentally induced ulcerative colitis found that rectal ozone reduced the inflammatory signalling molecules IL-17 and IL-23 and restored regulatory T cells - the immune system's peacekeepers - to healthy levels within six days. This is preclinical work, so it speaks to mechanism rather than to human outcomes, but the mechanism it shows is precisely the anti-inflammatory action practitioners describe.

A randomised controlled trial of 40 patients with IgA deficiency is relevant because IgA is the main antibody protecting the gut lining, and people with the deficiency are prone to intestinal infections such as giardiasis. Rectal ozone was associated with significant rises in IgG and IgM, improved antioxidant status, and a complete therapeutic response in 85% of patients against 45% of controls - with nothing more serious reported than brief bloating after insufflation.

There is also a published protocol for a clinical study on rectal ozone and gut microbiota - a sign that researchers consider the question worth formal investigation, though it has no results yet.

What about SIBO?

Small intestinal bacterial overgrowth is the question we get asked about most, so it deserves a straight answer in both directions.

On the formal evidence: there are no published clinical trials on ozone therapy for SIBO yet. We have looked hard, and we will publish the first one here when it appears. If a site tells you ozone is clinically proven for SIBO, ask them for the citation.

On practice: ozone is genuinely used for SIBO in clinics around the world, and anyone who spends an evening on YouTube, the SIBO forums or the integrative health podcasts will find a large body of first-person accounts. Certain themes recur across them: people who arrive at ozone after several rounds of antibiotics and relapse, reduced bloating and food reactivity over a course of treatment, and in some accounts a cleared breath test at the end. The practitioner reasoning behind this use is not hand-waving either - the organisms that overgrow in SIBO are largely anaerobes and are vulnerable to an oxidative, oxygen-rich environment; ozone is not an antibiotic, so the resistance problem that undermines repeated antibiotic courses does not apply in the same way; and drinking ozonated water delivers ozone through the stomach and small intestine, the actual site of the problem.

We report those accounts as what they are: experiences, in volume, consistent in their themes - and not a dataset. First-person accounts cannot tell us how often ozone works for SIBO, for whom, or at what dose, and the people for whom it did nothing rarely make videos. Both things are true at once: the testimonial landscape is substantial and genuinely encouraging, and the formal trial that would settle the question has not been run. In our view it is overdue.

One thing worth understanding when reading the research: the IBS study above measured colonic flora from stool samples, which reflects the large intestine. SIBO is diagnosed by breath testing and lives in the small intestine, a different environment. The IBS results are encouraging and adjacent, but they are not a SIBO trial - which is why we say the specific evidence does not exist yet, even though the surrounding evidence points in a promising direction.

If you are exploring ozone for SIBO, do it with a practitioner who knows the territory, and use breath testing before and after so you actually know whether it worked for you.

Ozonated water or rectal insufflation?

The two routes studied for gut applications work differently, and usefully so.

Drinking ozonated water is the route used in the H. pylori trial, and it is the more accessible one. Ozone dissolved in water has a short half-life, so it is made fresh and drunk immediately. Its action is on the stomach and upper digestive tract, including the small intestine - which is why it was the route chosen for a stomach organism, and why practitioners reach for it in small-intestine conditions.

Rectal insufflation delivers an ozone-oxygen mixture to the colon and is the route used in the IBS, colitis and IgA studies. Beyond its local effect on the colonic lining and flora, absorbed ozone metabolites act systemically - it is sometimes described as the gentler cousin of ozone autohaemotherapy. It requires an ozone generator and appropriate accessories, and dose matters: the studies above used carefully specified concentrations.

The IBS study used both routes together - and if your interest is the gut as a whole, that combination is exactly what produced its results.

The OZONODE - dose-adjustable from 4 to 92.5 µg/ml, factory-calibrated, and the generator behind both routes above.

What the home experience is like

The practical side matters as much as the science if you are weighing this up: can you actually run these protocols at home, without a technical background, as part of an ordinary morning? On that, our customers are better witnesses than we are. These are verified purchase reviews, quoted as published; we quote customers on the equipment and the experience rather than on health outcomes.

See more customer reviews →

Safety and sensible expectations

Across the human studies above, reported side effects were mild and transient - bloating immediately after insufflation, occasional abdominal discomfort. In the IgA trial, the ozone group actually reported fewer adverse events than the control group receiving standard injections. Ozone gas must never be inhaled directly, and dose and technique matter more here than in most things, which is why equipment quality and protocol are not incidental details.

Digestive symptoms have many causes, some of them serious, and several of them look alike from the outside. Persistent changes in bowel habit, unexplained weight loss, bleeding or ongoing pain need a doctor first. If you have a diagnosed gastrointestinal condition, keep the clinician managing it in the loop, and do not stop prescribed treatment on your own.

Ozone therapy in New Zealand

Ozone therapy in New Zealand occupies the same ground as much of complementary health: no legislation prohibits it, and no registration scheme formally approves it. It sits outside the registered-medicine framework rather than against it, and it is practised here by trained practitioners and used at home throughout the country.

The professional body for the field is the Ozone Therapy Association of New Zealand (OTANZ), which trains and supports practitioners, has been a member of the International Medical Ozone Federation since 2018, and adheres to the Madrid Declaration on Ozone Therapy, the international consensus document on safe practice. Natural Ozone is a member of OTANZ.

Internationally, ozone therapy is recognised as a medical procedure in a number of countries, including Germany, Italy, Spain, Turkey, China and Cuba, and was introduced into Brazil's public health system as a complementary practice in 2018. Here, we present the research and leave treatment decisions where they belong - with you and your health practitioner.

Where the evidence stands

Here is the honest summary, and it is more encouraging than a quick glance suggests. Every controlled study to date on ozone and the gut has reported results in ozone's favour: the H. pylori trial, the IBS microbiota study, the IgA deficiency trial, the colitis model, and now microbiome sequencing work. The findings agree with each other and with the proposed mechanism - beneficial organisms up, problem organisms down, inflammation reduced, with mild side effects. What the field lacks is volume: more trials, bigger trials, and the first SIBO trial. Nothing published points the other way.

That is a picture worth taking seriously. The studies linked above are worth reading in full, limitations included - which is exactly why we publish them that way.

If you are weighing up whether ozone therapy suits your situation and want a straight answer rather than a sales pitch, get in touch.