A SIBO breath test checks for small intestinal bacterial overgrowth by measuring hydrogen and methane in breath after a drink of lactulose or glucose. The 2017 North American consensus treats a hydrogen rise of 20 ppm or more within 90 minutes, or methane of 10 ppm or more, as positive. Results depend heavily on preparation, and fast gut transit can give false positives. Nutripath also offers a fructose arm for fructose malabsorption. Verified practitioners can order the kits through Vively.
| Test type | Measured in breath samples |
|---|---|
| Nutripath code | 2025, 2030, 2021, 2027, 2215 |
| Sample and collection | Breath kit collected at home and posted to Nutripath |
| Preparation | No antibiotics for 4 weeks and no bowel prep or colonoscopy in the weeks before. A restricted diet the day before, then an 8 to 12 hour fast. No smoking or exercise during the test. |
| Turnaround | 1 business day for every SIBO breath test (Nutripath estimate, from when the lab receives the kit). Allow extra days for postage. |
| Available through | Nutripath test ordered through Vively. You need to be a verified practitioner to refer it. |
| Pricing | Pricing in your practitioner account |
| Results | PDF report from Nutripath, filed in your client’s record and app beside their blood results |
Only practitioners can order this test. Ask your naturopath, nutritionist or dietitian whether they use Vively.
What does a SIBO breath test measure?
People don’t make hydrogen or methane; gut microbes do. When they ferment a sugar, the gas is absorbed into the blood and breathed out. The timing of the rise shows roughly where the fermentation is happening.
An early rise in hydrogen after the test sugar suggests bacteria in the small bowel. Hydrogen predominant SIBO is often linked with diarrhoea and bloating.
Methane comes from archaea, mainly Methanobrevibacter smithii, which use hydrogen to make it. Raised methane is linked with constipation. The consensus calls this intestinal methanogen overgrowth, because the archaea are not always in the small bowel.
Lactulose isn’t absorbed, so it travels the whole small bowel and can find distal overgrowth, but fast transit can carry it into the colon early. Glucose is absorbed in the upper small bowel, so a positive result is more specific, but it can miss overgrowth further down.
The fructose test looks for fructose malabsorption, not SIBO. Nutripath includes it in the combined kits so a fructose reaction can be told apart from a SIBO pattern.
| Nutripath test | Code | Sample | Turnaround |
|---|---|---|---|
| SIBO Breath Test, lactulose | 2025 | Breath | 1 business day |
| SIBO Breath Test, glucose | 2030 | Breath | 1 business day |
| SIBO Breath Test, fructose | 2021 | Breath | 1 business day |
| SIBO Breath Test, fructose and lactulose | 2027 | Breath | 1 business day |
| SIBO Breath Test, fructose, lactulose and glucose | 2215 | Breath | 1 business day |
How do you order a SIBO breath test through Vively?
- Get verified. You need to be a verified practitioner to refer tests. Practitioners with a recognised qualification or membership (ATMS, NHAA, ANTA, Dietitians Australia, NSA, CMA or Ahpra registration) can request free practitioner access.
- Build the order. Log in to the practitioner platform, choose the Nutripath test and add any blood tests or the $99 Baseline Health Check to the same order. Pricing shows in your account, and either your client or your practice can pay.
- Client collects at home. Nutripath sends your client the collection kit once the order is placed. Your client follows the kit instructions (a baseline breath sample, then breath samples at set times over 2 to 3 hours after drinking the test sugar) and posts the sample back to Nutripath in the packaging provided.
- Review the report. Nutripath’s PDF report is filed in your client’s record and app, next to their blood results, ready for the follow-up consult.
See every Nutripath test you can order on the Nutripath tests page.
Order a SIBO breath test with your client’s blood tests
Free access for verified naturopaths, nutritionists and dietitians. Order Nutripath tests and blood pathology in one place, and see every result in your client’s record.
What does a SIBO breath test tell you, and what does it not?
Breath testing is the only practical test for SIBO outside a hospital, and it has real limits. Read it as one piece of the picture.
The North American consensus treats a hydrogen rise of 20 ppm or more above baseline by 90 minutes as positive for SIBO, and methane of 10 ppm or more at any point as positive for methanogen overgrowth (Rezaie et al., 2017). Not every lab uses the same cut-offs, so read the criteria on the Nutripath report.
If the lactulose reaches the colon early, normal colonic bacteria produce hydrogen and the test can look positive. Recent diarrhoea and some medicines speed transit.
Glucose can miss overgrowth in the lower small bowel. Some people’s gut bacteria produce hydrogen sulphide instead of hydrogen, which these tests don’t measure.
Culture of small bowel fluid taken at endoscopy is the reference test, but it is invasive and rarely done. Breath testing is a practical substitute, not an equivalent.
How does a SIBO breath test fit with blood work?
SIBO can affect absorption, and its symptoms overlap with conditions a breath test can’t see. Order blood markers with the breath test to cover both.
- ContextPositive breath test with low vitamin B12
Bacteria in the small bowel can use up B12. Folate is often normal or high, because the bacteria make it.
- ReferPositive breath test with low ferritin, weight loss or night time symptoms
SIBO doesn’t explain these on its own. Refer to the GP to look for an underlying cause such as coeliac disease or inflammatory bowel disease.
- ContextEarly hydrogen rise on lactulose with loose stools
Could be SIBO or fast transit. A glucose test, or the history, can help tell them apart.
- LowNegative breath test, normal iron and B12
SIBO is less likely. Look at other drivers such as IBS, fructose or lactose malabsorption, and diet.
What can affect a SIBO breath test result?
- Antibiotics in the 4 weeks before the test
- A colonoscopy or bowel prep in the weeks before
- Not following the prep diet or the fast
- Laxatives or promotility medicines in the week before, if the prescriber agrees to stop them
- Smoking, sleeping or exercising during the test
When should you refer the client to their GP?
- Weight loss, rectal bleeding, iron deficiency or night time diarrhoea
- Symptoms that start after age 50 or change quickly
- Previous bowel surgery, diabetes with gut symptoms, scleroderma or other conditions that slow the gut
- A positive result that keeps coming back after treatment
- Any client who may need antibiotics, which a GP prescribes
How should a client prepare for a SIBO breath test?
Copy or print this to send to your client. Follow the instructions in the Nutripath kit if they differ.
Preparing for your SIBO breath test
- Don’t take antibiotics for 4 weeks before the test, and wait a few weeks after a colonoscopy. Ask your doctor before stopping laxatives or other gut medicines, ideally for a week before.
- Follow the prep diet in your kit the day before. It usually means plain foods such as rice, eggs, meat or fish, and no fibre, dairy or fruit.
- Fast for 8 to 12 hours before the test. You can drink water.
- Do the test in the morning. Collect the first breath sample, drink the test sugar, then collect each sample at the times the kit gives.
- Sit quietly during the test. Don’t eat, smoke, exercise or sleep until the last sample is done.
- Post the kit back the same day, early in the week so it isn’t in the post over the weekend.
What does the SIBO breath test report look like?
Nutripath publishes sample reports on its website. They open in a new tab.
How do practitioners use SIBO breath testing with clients?
Use it when bloating, wind and changed bowel habits haven’t settled with first line changes, and red flags have been ruled out. Lactulose is the usual first test. A glucose test is more specific and helps when you suspect fast transit. Add the fructose arm if fructose foods are a clear trigger. Put most of your effort into the prep: a missed fast or a recent antibiotic makes the result hard to read. If treatment needs antibiotics, write to the GP with the report.
SIBO breath test FAQs
Can a naturopath, nutritionist or dietitian order a SIBO breath test through Vively?
Yes. You need to be a verified practitioner to refer it. Add a Nutripath SIBO breath test to an order in the Vively practitioner platform, on its own or with blood tests. Pricing shows in your account. No account yet? Request free access.
Should I choose the lactulose or the glucose SIBO test?
Lactulose covers the whole small bowel but gives more false positives with fast transit. Glucose is more specific but can miss overgrowth lower down. Many practitioners start with lactulose, or choose a combined kit.
What does methane on a breath test mean?
Methane of 10 ppm or more at any point suggests overgrowth of methane producing archaea, called intestinal methanogen overgrowth. It is linked with constipation.
What does the fructose breath test add?
It checks for fructose malabsorption, a separate cause of bloating and loose stools after fruit, honey and some sweeteners. Nutripath uses it to tell a fructose reaction apart from SIBO.
How long do SIBO breath test results take?
Nutripath estimates 1 business day for all five breath tests, from when the lab receives the kit. Allow a few extra days for postage.
References
- 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;112(5):775-784.
- Pimentel M, Saad RJ, Long MD, Rao SSC. ACG clinical guideline: small intestinal bacterial overgrowth. American Journal of Gastroenterology. 2020;115(2):165-178.
- Nutripath. SIBO breath tests, test codes 2025, 2030, 2021, 2027 and 2215. nutripath.com.au, checked 1 October 2026.