Lab result explainedMetabolic panelLast updated November 11, 2026

SIBO breath test: how to prepare, what positive hydrogen and methane results mean, and how accurate it is

SIBO breath test (SIBO breath test) · Hydrogen and methane breath test with lactulose or glucose (stand-alone test, in clinic or with a mail-in kit) · reported in ppm (parts per million) of hydrogen and methane in exhaled breath, reported at each time point and as the rise from baseline

A SIBO breath test measures hydrogen and methane in your breath over two to three hours after you drink a sugar solution, to look for small intestinal bacterial overgrowth: too many bacteria living in the small bowel, where they ferment food before you can absorb it. Human cells do not make hydrogen or methane; gut microbes do, and the gases diffuse into the blood and out through the lungs. Under the North American consensus used by most US labs, the test is positive for SIBO if hydrogen rises by 20 parts per million (ppm) or more above baseline within 90 minutes, and positive for intestinal methanogen overgrowth (IMO) if methane reaches 10 ppm at any point.

The test is ordered for bloating, gas, diarrhea, constipation or abdominal pain that has not been explained, particularly in people with risk factors such as long-term acid-suppressing medication, diabetes, previous bowel surgery, scleroderma, celiac disease or Crohn's disease. It has become popular because it is non-invasive and can be done at home, but it is an indirect test with real limitations: sensitivity and specificity are both modest, a lactulose test can read positive simply because the sugar reached the colon quickly, and about 15 to 20 percent of people produce neither gas in measurable amounts.

Preparation matters more for this test than for almost any other. Antibiotics in the previous four weeks, laxatives or motility drugs in the previous week, a high-fiber meal the day before, or smoking or exercising on the morning of the test can all distort the curve and produce a false result in either direction. Done properly and interpreted alongside your symptoms, the breath test is the most practical way to identify SIBO or IMO and to pick between treatments that target hydrogen producers and those aimed at methane producers.

SIBO breath test at a glance

  • What it is: breath samples every 15 to 20 minutes for 2 to 3 hours after drinking 10 g of lactulose or 75 g of glucose; the lab measures hydrogen and methane in parts per million (ppm).
  • Positive for SIBO (hydrogen): a rise of 20 ppm or more above baseline within 90 minutes (North American consensus, 2017).
  • Positive for IMO (methane): 10 ppm or more at any point during the test, including baseline; methane is linked to constipation.
  • Preparation: no antibiotics for 4 weeks; no laxatives, prokinetics or probiotics for 1 week; a low-fermentation diet (plain rice, meat, fish, eggs, clear broth) the day before; fast 8 to 12 hours; no smoking, vigorous exercise or sleeping during the test.
  • Accuracy is moderate: compared with small-bowel aspirate culture, sensitivity is roughly 30 to 70 percent and specificity 45 to 85 percent; false positives occur with fast transit and false negatives in people whose microbes make neither gas.
  • Baseline hydrogen above 20 ppm usually means poor preparation; the test is repeated rather than interpreted.

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What SIBO breath test measures

After you drink the test sugar, any bacteria it meets ferment it and release hydrogen; a subset of gut organisms (archaea, mainly Methanobrevibacter smithii) convert that hydrogen into methane. Both gases cross the gut wall, travel in the blood and are exhaled, so breath concentrations rise in step with fermentation. In a healthy small intestine there are too few bacteria to ferment much, so breath hydrogen stays flat until the sugar reaches the colon. An early rise means fermentation is happening in the small bowel, which is the signature of overgrowth.

The two substrates behave differently. Glucose is absorbed completely in the first part of the small intestine, so a rise can only come from bacteria in the upper small bowel; it is more specific but misses overgrowth further down. Lactulose is not absorbed by humans at all, so it travels the whole small intestine and into the colon; it can detect distal overgrowth but produces a hydrogen peak whenever it reaches the colon, which in people with fast transit can happen well within 90 minutes and mimic SIBO. The 90-minute cut-off is a compromise; the classic 'double peak' pattern once taught as diagnostic is no longer considered reliable.

The reference standard the breath test is judged against is a culture of fluid aspirated from the jejunum during endoscopy, with 1,000 colony-forming units per milliliter or more (the 2020 American College of Gastroenterology threshold; older studies used 100,000) counting as overgrowth. That procedure is invasive, samples a single spot and has its own contamination problems, which is why breath testing is used in practice despite its imperfections. Some labs now add hydrogen sulfide, a third gas produced by sulfate-reducing bacteria and proposed as the explanation for 'flat line' tests in people with diarrhea; a cut-off of 3 ppm or more has been suggested but is not yet part of any consensus guideline.

Normal range for SIBO breath test

Reference ranges vary between labs and by age, sex and pregnancy. Use the range printed on your own report.

GroupTypical range (ppm (parts per million) of hydrogen and methane in exhaled breath, reported at each time point and as the rise from baseline)Notes
Baseline hydrogen (fasting)Below 10 ppm expected; above 20 ppm indicates inadequate preparationA high start usually reflects fermentable food the day before or a shortened fast. Most labs ask you to repeat the test rather than interpret it.
Hydrogen, negative for SIBORise of less than 20 ppm above baseline through 90 minutesA later rise (after 90 to 120 minutes with lactulose) is the normal colonic peak, not overgrowth.
Hydrogen, positive for SIBORise of 20 ppm or more above baseline by 90 minutesNorth American consensus 2017, adopted by the 2020 ACG guideline. Some European labs use 120 minutes for lactulose or a 12 ppm rise for glucose.
Methane, negativeBelow 10 ppm at every time pointLow-level methane (1 to 9 ppm) is common and not considered overgrowth.
Methane, positive for IMO10 ppm or more at any time point, including baselineCalled intestinal methanogen overgrowth rather than SIBO because methane producers are archaea, not bacteria, and often live in the colon. Strongly associated with constipation; higher levels track slower transit.
Combined hydrogen plus methane (some labs)A rise of 15 ppm or more in the sumUsed by a few laboratories; not part of the North American consensus. Ask which criterion your lab applied.
Flat line (non-producer)Hydrogen and methane both stay under 5 ppm throughoutSeen in about 15 to 20 percent of tests. May mean a true negative, a technical problem, or hydrogen sulfide production that standard tests do not measure.
Hydrogen sulfide (where measured)3 ppm or more proposed as positiveAvailable on a three-gas test. Early data only; not validated in guidelines and treatment implications are uncertain.

Positive SIBO breath test

A positive hydrogen result means the test sugar was fermented early, in the time it should have been passing through a nearly sterile small intestine, which is consistent with bacterial overgrowth there. Overgrowth is not an infection with a particular germ; it is ordinary colon-type bacteria in the wrong place and in the wrong numbers, usually because something has weakened the defenses that normally keep the small bowel sparsely populated: stomach acid, the sweeping contractions between meals (the migrating motor complex), the ileocecal valve and normal bowel anatomy. The practical consequences are fermentation of carbohydrates (bloating, gas, distension), deconjugation of bile salts (fatty stools, diarrhea) and, when severe, poor absorption of vitamin B12, iron and fat-soluble vitamins.

A positive methane result (10 ppm or more) is a different problem with a different signature. Methane-producing archaea slow intestinal transit, so IMO is associated with constipation rather than diarrhea, and the degree of methane correlates with constipation severity. Because the archaea often live in the colon as well as the small bowel, treatment aimed at hydrogen producers alone often fails, which is why the two results are reported separately and why your clinician will want to know which gas rose.

The size of the rise is a weak guide to severity and a poor predictor of how you will respond to treatment. What matters more is whether the positive result fits your symptoms and risk factors, and whether an underlying cause can be found and addressed, because SIBO recurs in roughly 40 to 45 percent of people within 9 months of a successful antibiotic course when the cause (a proton pump inhibitor, slow motility, a surgical loop, uncontrolled diabetes) is still there. A positive test in someone with no symptoms is not treated.

Common causes

  1. Long-term proton pump inhibitor use

    Stomach acid kills most swallowed bacteria. A meta-analysis of 11 studies found PPI users had about 1.7 times the odds of SIBO, with the clearest effect when overgrowth was defined by small-bowel culture.

  2. Slow small-bowel motility

    Diabetes with autonomic neuropathy, hypothyroidism, scleroderma, Parkinson's disease, opioid painkillers, gastroparesis and some antidepressants and antispasmodics weaken the migrating motor complex that sweeps bacteria downstream between meals. This is the most common mechanism in people without surgery.

  3. Structural changes and surgery

    Blind loops after gastric bypass or Billroth II surgery, removal of the ileocecal valve, strictures in Crohn's disease, small-bowel diverticula, adhesions and fistulas all create pockets where bacteria stagnate and multiply.

  4. Irritable bowel syndrome

    Depending on the test used, 30 to 60 percent of people with IBS test positive, compared with roughly 10 to 20 percent of controls, and SIBO is most common in diarrhea-predominant IBS. Whether SIBO causes IBS, results from it, or shares a cause is still debated.

  5. Celiac disease, chronic pancreatitis and cirrhosis

    Villous damage and slowed transit in untreated celiac disease, loss of pancreatic enzymes, and portal hypertension with reduced motility in cirrhosis each raise SIBO rates to 30 to 50 percent and are reasons to look for SIBO when symptoms persist despite treatment of the primary condition.

  6. Older age and immune deficiency

    Reduced acid, slower transit and more medication make SIBO common after 70, and low IgA or common variable immunodeficiency removes the mucosal antibody that limits bacterial numbers.

  7. Rapid transit (false positive with lactulose)

    In people whose oral-to-cecal transit time is under 90 minutes, which includes many with diarrhea, lactulose reaches the colon before the cut-off and the normal colonic peak is misread as SIBO. Scintigraphy studies suggest this accounts for a substantial share of positive lactulose tests.

  8. Poor preparation

    Fermentable food within 24 hours, a fast shorter than 8 hours, smoking, sleep or exercise during the test, or recent fiber supplements raise baseline and early hydrogen and can tip a borderline test over the 20 ppm line.

Symptoms that can go with it

  • Bloating and visible abdominal distension that worsens through the day and after carbohydrate-rich meals
  • Excess gas, belching and flatulence
  • Diarrhea or loose, pale, greasy, foul-smelling stools (hydrogen-predominant)
  • Constipation, hard stools and a sense of incomplete emptying (methane-predominant)
  • Abdominal pain, cramping or discomfort relieved by passing gas or stool
  • Nausea, early fullness and reduced appetite
  • Weight loss, fatigue, numbness or tingling, or a sore tongue from vitamin B12, iron or fat-soluble vitamin malabsorption in more severe cases

Negative or flat-line SIBO breath test

A negative test, with hydrogen rising less than 20 ppm by 90 minutes and methane staying under 10 ppm, makes small-bowel overgrowth less likely but does not exclude it. Breath testing misses a meaningful share of culture-proven SIBO (sensitivity in studies ranges from about 30 to 70 percent depending on substrate and criteria), a glucose test cannot see overgrowth beyond the upper small bowel, and someone who took antibiotics, probiotics or a motility agent in the weeks before the test may have a temporarily suppressed result. If symptoms are typical and risk factors are strong, clinicians sometimes repeat the test with the other substrate or treat on clinical grounds.

A 'flat line', where neither gas rises at all even after the sugar should have reached the colon, is seen in roughly 15 to 20 percent of tests and is a technical result rather than a clean negative. Possible explanations include a microbiome dominated by hydrogen sulfide producers (which consume hydrogen and are not detected by two-gas tests), very slow transit so the sugar never reached fermenting bacteria during the recording window, recent antibiotics, or a faulty sample. A three-gas test or a repeat after proper preparation can clarify.

Most importantly, a negative breath test redirects attention rather than ending the search. Bloating, diarrhea and pain have many other causes that are more common than SIBO, including irritable bowel syndrome, celiac disease, lactose or fructose intolerance (which have their own breath tests), bile acid diarrhea, exocrine pancreatic insufficiency, microscopic colitis, inflammatory bowel disease and constipation with overflow. A negative SIBO test is a reasonable point to make sure celiac serology, fecal calprotectin and, where indicated, fecal elastase have been done.

Common causes

  1. Genuinely no overgrowth

    The commonest explanation. Symptoms are then more likely to be IBS, a food intolerance, a functional bowel disorder or one of the organic conditions above.

  2. Recent antibiotics, probiotics or herbal antimicrobials

    Any of these in the preceding 2 to 4 weeks can suppress gas production enough to produce a false negative; the consensus asks for a 4-week antibiotic-free interval and 1 week off probiotics.

  3. Glucose substrate with distal overgrowth

    Glucose is absorbed in the first 3 feet or so of small intestine, so bacteria further along never see it. A lactulose test or clinical treatment trial may be considered if suspicion remains high.

  4. Hydrogen sulfide-dominant microbes

    Sulfate-reducing bacteria use up hydrogen to make hydrogen sulfide, which standard two-gas analyzers do not measure; this is the leading theory for flat-line tests in people with diarrhea.

  5. Very slow transit or gastroparesis

    If the sugar is still in the stomach or upper small bowel when the test ends, no fermentation is recorded. Methane-predominant people and those with gastroparesis are at particular risk of this false negative.

  6. Sample or device problems

    Leaky collection bags, delayed mailing of home kits in hot conditions, or poor technique (not exhaling end-expiratory air) lower measured concentrations across the board.

Symptoms that can go with it

  • None caused by the result itself; a negative test does not explain ongoing symptoms
  • Persistent bloating, diarrhea, constipation or pain despite a negative test warrants evaluation for celiac disease, IBS, lactose or fructose intolerance, bile acid diarrhea and pancreatic insufficiency
  • Weight loss, blood in the stool, anemia, nighttime symptoms or onset after age 50 are alarm features that need endoscopy or imaging regardless of the breath test

Read it alongside

  • tTG-IgA (with total IgA) — celiac disease causes the same symptoms and predisposes to SIBO; it should be tested while still eating gluten.
  • Fecal calprotectin — distinguishes inflammatory bowel disease from IBS or SIBO when diarrhea and pain persist; a level under 50 µg/g makes active inflammation unlikely.
  • Fecal elastase — low values (under 200 µg/g) point to pancreatic insufficiency, which coexists with and mimics SIBO.
  • Vitamin B12, folate and methylmalonic acid — overgrown bacteria consume B12 and produce folate, so low B12 with high or high-normal folate is a classic SIBO pattern.
  • Ferritin and vitamin D — fall with malabsorption in more severe or long-standing overgrowth.
  • A1C and glucose — diabetes with neuropathy is a leading cause of slow motility and recurrent SIBO; control matters for preventing relapse.
  • TSH — hypothyroidism slows transit and is an easily corrected contributor to both SIBO and methane overgrowth.
  • H. pylori test — a separate question, but relevant if you are on a PPI for ulcer or reflux symptoms that might be managed differently.
  • Lactose and fructose breath tests — the same technology with a different sugar; they identify intolerances that cause identical bloating without any overgrowth.

What usually happens next

  1. Positive hydrogen: expect a discussion of a 10 to 14 day course of an antibiotic such as rifaximin (about 60 to 70 percent normalize the test), and just as importantly a search for the cause: medication review (especially acid suppressants and opioids), glucose control, thyroid function and any surgical history.
  2. Positive methane: treatment is usually a combination aimed at archaea rather than a single antibiotic, and constipation is managed alongside; ask how success will be judged, since repeat testing is not always needed if symptoms resolve.
  3. After treatment: symptom response is the main yardstick. A repeat breath test is reasonable if symptoms persist or recur, and about 4 in 10 people relapse within 9 months, so a prevention plan (addressing the cause, sometimes a prokinetic at night, meal spacing) is worth asking about.
  4. Negative or flat line: check that celiac serology, fecal calprotectin and, if stools are greasy, fecal elastase have been done; consider lactose and fructose breath tests, and ask whether a three-gas test or a repeat with the other substrate makes sense.
  5. Borderline (rise of 15 to 19 ppm, or methane 7 to 9 ppm): usually treated as negative under consensus criteria; a repeat after meticulous preparation, or treating based on the clinical picture, are both reasonable options to discuss.
  6. Before any repeat test, allow 4 weeks after antibiotics and 1 week off probiotics, laxatives and motility agents, and follow the preparation diet exactly, because most uninterpretable tests are preparation failures.

Diet, lifestyle and natural levers with evidence

What can move SIBO breath test once the cause is known. Nothing here replaces finding the cause.

Low-FODMAP diet for symptoms (not as a treatment for overgrowth)

Strong evidence

Restricting fermentable carbohydrates reduces the substrate bacteria ferment, and in randomized trials in IBS it improves bloating, pain and stool form in 50 to 75 percent of people within 2 to 4 weeks, with measurable reductions in breath hydrogen. It does not reduce bacterial numbers in the small bowel and is not a treatment for SIBO itself; it is used for symptom control before, during or after antimicrobial treatment, followed by structured reintroduction over 6 to 8 weeks.

Long-term strict restriction lowers beneficial colonic bacteria and fiber intake; work with a dietitian and reintroduce foods. Stop the diet at least 1 to 2 days before a breath test only as instructed by the lab, since the standard preparation is itself low-fermentation.

Partially hydrolyzed guar gum alongside treatment

Moderate evidence

In a randomized trial of 77 people with SIBO, adding 5 g a day of partially hydrolyzed guar gum to a 10-day rifaximin course raised breath-test normalization from 62 percent with rifaximin alone to 87 percent, with greater symptom improvement. The proposed mechanism is that a soluble fiber keeps bacteria metabolically active and more susceptible to the antibiotic. It is one of the few supplements tested in a controlled trial for this specific purpose.

Start low (2 to 3 g) because any fermentable fiber can increase gas in the first week; stop 1 week before a breath test.

Herbal antimicrobial combinations

Preliminary evidence

A retrospective study of 104 patients at Johns Hopkins compared 4 weeks of commercial herbal blends (containing berberine, oregano oil, thyme, wormwood and other antimicrobials) with 10 days of rifaximin: 46 percent of the herbal group normalized the lactulose breath test versus 34 percent on rifaximin, a difference that was not statistically significant, and herbs also helped some rifaximin non-responders. There are no randomized trials, the products varied, and dosing is not standardized, so this is an option to raise with a clinician rather than a validated treatment.

Berberine should not be used in pregnancy, while breastfeeding or in newborns (risk of kernicterus), lowers blood sugar, and interacts with many drugs through CYP enzymes including cyclosporine. Oregano oil and wormwood are irritant and not for long-term use.

Probiotics

Preliminary evidence

A 2017 meta-analysis of 18 studies found probiotics normalized the breath test in about 53 percent of treated people versus a pooled rate of about 1 in 3 with placebo or no probiotic (relative risk 1.6), lowered breath hydrogen and reduced abdominal pain, but did not prevent SIBO from developing and the trials were small and heterogeneous. Strains and doses varied widely, so no specific product can be recommended; some people with SIBO feel more bloated on probiotics, particularly those containing prebiotic fibers.

Stop probiotics 1 week before a breath test. People with central venous lines, severe illness or significant immune suppression should avoid live probiotic supplements.

Meal spacing and overnight fasting to support the migrating motor complex

Preliminary evidence

The migrating motor complex, the cleansing wave that moves bacteria down the gut, runs only in the fasting state and is interrupted by eating. Physiological studies show it resumes about 90 minutes to 2 hours after a meal, which is the rationale for leaving 4 to 5 hours between meals and 12 hours overnight; this is standard advice in gastroenterology clinics to reduce recurrence, though no randomized trial has measured its effect on relapse rates. Ginger (1 to 1.5 g a day) accelerates gastric emptying in small trials and is sometimes used as a mild prokinetic.

Prolonged fasting is inappropriate for people who are underweight, pregnant, diabetic on insulin or with a history of an eating disorder; discuss first.

Reviewing acid suppression, alcohol and opioids

Moderate evidence

Because PPIs raise SIBO odds by about 1.7-fold, stepping down to the lowest effective dose, switching to an H2 blocker or stopping when the original indication has passed is one of the most effective ways to prevent recurrence; roughly a third of long-term PPI users in primary care have no ongoing indication. Moderate to heavy alcohol use is associated with SIBO in several studies, and opioids slow motility directly. None of these is a supplement, but all change the result more reliably than anything you can buy.

Do not stop a PPI prescribed for Barrett's esophagus, a healing ulcer, or protection while on anticoagulants or NSAIDs without discussing it; rebound acid for 2 to 4 weeks after stopping is common and manageable.

When to see a clinician promptly

  • Unintentional weight loss of more than 5 percent of body weight, blood in the stool or black stools, persistent vomiting, or new symptoms after age 50: these need endoscopy or imaging, not a breath test.
  • Severe abdominal pain with a rigid or very tender abdomen, fever or inability to pass stool or gas: possible obstruction or perforation, go to the emergency department.
  • Signs of significant malabsorption: greasy stools with weight loss, numbness or tingling, a sore tongue, easy bruising or night blindness, which suggest vitamin B12, fat-soluble vitamin or iron deficiency that needs measuring and replacing.
  • Diarrhea lasting more than 4 weeks, or waking you at night, especially with a family history of celiac or inflammatory bowel disease.
  • A positive breath test with a known structural cause (previous bowel surgery, Crohn's strictures, scleroderma), because management and recurrence prevention are different and a gastroenterologist should be involved.
  • Repeated courses of antibiotics or herbal antimicrobials with symptoms returning each time, which means the underlying cause has not been addressed and the diagnosis should be revisited.

Frequently asked questions

What is a positive SIBO breath test?

Under the North American consensus used by most US labs, the test is positive for SIBO if breath hydrogen rises by 20 ppm or more above your fasting baseline within 90 minutes of drinking the sugar, and positive for intestinal methanogen overgrowth (IMO) if methane reaches 10 ppm or more at any point, including at baseline. A rise after 90 minutes is usually the sugar reaching the colon, which is normal. Some labs also report a combined hydrogen-plus-methane rise of 15 ppm, which is not a consensus criterion.

How do I prepare for a SIBO breath test?

No antibiotics for 4 weeks; no laxatives, stool softeners, prokinetics, probiotics or fiber supplements for 1 week. The day before, eat only low-fermentation foods such as plain white rice, baked or broiled chicken, fish or eggs, clear broth, and water, with no fruit, vegetables, beans, dairy, bread, sweeteners or alcohol. Fast for 8 to 12 hours overnight (water only), skip breakfast, and do not smoke, chew gum, exercise or sleep during the test. Brush your teeth before the baseline sample. Proton pump inhibitors do not need to be stopped under the consensus, but follow your lab's instructions.

How accurate is the SIBO breath test?

Moderately. Against small-bowel aspirate culture, the glucose test has a sensitivity of roughly 20 to 90 percent and specificity of 30 to 85 percent across studies, and the lactulose test about 30 to 70 percent sensitivity and 45 to 100 percent specificity, with most estimates in the middle of those ranges. False positives come mainly from fast transit on lactulose tests and poor preparation; false negatives from overgrowth beyond the reach of glucose, recent antibiotics and non-gas-producing microbes. It is useful when the result matches the clinical picture, and unreliable as a stand-alone verdict.

What is the difference between the lactulose and glucose breath tests?

Glucose is absorbed in the upper small intestine, so a rise can only come from bacteria there; it is more specific but misses overgrowth lower down. Lactulose is not absorbed, so it tests the whole small bowel but reaches the colon and produces a hydrogen peak in everyone, which in people with fast transit can happen within 90 minutes and look like SIBO. Guidelines accept either; many US clinics use lactulose, many European centers prefer glucose, and some clinicians order the other substrate when the first result does not fit.

What does high methane on a SIBO test mean?

Methane of 10 ppm or more means overgrowth of methane-producing archaea, now called intestinal methanogen overgrowth (IMO) rather than SIBO because they are not bacteria and often live in the colon too. Methane slows gut transit, so IMO is linked to constipation, bloating and a feeling of incomplete emptying rather than diarrhea, and the higher the methane the more severe the constipation tends to be. Treatment differs from hydrogen-predominant SIBO and usually targets the archaea specifically.

My SIBO test was negative but I still have symptoms. What now?

A negative test lowers the chance of SIBO but does not rule it out, and it does not explain your symptoms, so the next step is to look elsewhere: celiac testing (tTG-IgA with total IgA, while still eating gluten), fecal calprotectin for inflammation, fecal elastase if stools are greasy, and lactose or fructose breath tests, which use the same technology to find intolerances that cause identical bloating. Irritable bowel syndrome remains the most common diagnosis, and a low-FODMAP trial helps 50 to 75 percent of people with it. If the trace was completely flat, a three-gas test or a repeat after careful preparation may be worthwhile.

Are at-home SIBO breath test kits reliable?

Mail-in kits from clinical laboratories use the same gas analyzers as in-clinic tests and, when the instructions are followed exactly and samples are returned promptly, give comparable results; most US tests are now done this way. The weak points are preparation, collection technique (you must exhale end-expiratory air into the tube) and delays or heat in transit. Kits sold without a clinician's involvement or that promise to diagnose 'gut imbalance' from a single sample are not the same thing. Any positive result should be interpreted by someone who can weigh it against your symptoms and risk factors.

Does SIBO come back after treatment?

Often. In a study following patients after successful rifaximin treatment, 13 percent had relapsed at 3 months, 28 percent at 6 months and 44 percent at 9 months, with older age, previous appendectomy and long-term PPI use predicting recurrence. Relapse is much less likely when the underlying cause is fixed, whether that is stepping down acid suppression, improving diabetic control, treating hypothyroidism or, where appropriate, using a low-dose prokinetic at night. Repeated antibiotic courses without addressing the cause are the main reason people stay on the treatment merry-go-round.

References

  1. Rezaie A, Buresi M, Lembo A, et al.. Hydrogen and methane-based breath testing in gastrointestinal disorders: the North American Consensus. American Journal of Gastroenterology (2017)
  2. Pimentel M, Saad RJ, Long MD, Rao SSC. ACG Clinical Guideline: Small intestinal bacterial overgrowth. American Journal of Gastroenterology (2020)
  3. Khoshini R, Dai SC, Lezcano S, Pimentel M. A systematic review of diagnostic tests for small intestinal bacterial overgrowth. Digestive Diseases and Sciences (2008)
  4. Hammer HF, Fox MR, Keller J, et al.. European guideline on indications, performance, and clinical impact of hydrogen and methane breath tests in adult and pediatric patients. United European Gastroenterology Journal (2022)
  5. Lauritano EC, Gabrielli M, Scarpellini E, et al.. Small intestinal bacterial overgrowth recurrence after antibiotic therapy. American Journal of Gastroenterology (2008)
  6. Lo WK, Chan WW. Proton pump inhibitor use and the risk of small intestinal bacterial overgrowth: a meta-analysis. Clinical Gastroenterology and Hepatology (2013)
  7. Furnari M, Parodi A, Gemignani L, et al.. Clinical trial: the combination of rifaximin with partially hydrolysed guar gum is more effective than rifaximin alone in eradicating small intestinal bacterial overgrowth. Alimentary Pharmacology and Therapeutics (2010)
  8. Chedid V, Dhalla S, Clarke JO, et al.. Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Global Advances in Health and Medicine (2014)
  9. Zhong C, Qu C, Wang B, Liang S, Zeng B. Probiotics for preventing and treating small intestinal bacterial overgrowth: a meta-analysis and systematic review of current evidence. Journal of Clinical Gastroenterology (2017)
  10. Halmos EP, Power VA, Shepherd SJ, Gibson PR, Muir JG. A diet low in FODMAPs reduces symptoms of irritable bowel syndrome. Gastroenterology (2014)
  11. Small intestinal bacterial overgrowth (SIBO). Mayo Clinic (2024)View source
  12. Small intestinal bacterial overgrowth (SIBO). Merck Manual Professional Version (2024)

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This page is educational and is not medical advice or a diagnosis. Lab results have to be interpreted together with your history, symptoms and other results by a clinician who knows you. Do not start or stop a supplement to change a lab value before the cause is known.