Is a Bacterial Overgrowth Breath Test Really Worth It?

Does your gut need a reset?

Yes, I'm Ready

Do you want to start feeling better?

Yes, Where Do I Start?

Do you want to start feeling better?

Yes, Where Do I Start?

Is a Bacterial Overgrowth Breath Test Really Worth It?

A Breath Test May Not Be the Best First Step for Treating SIBO

Key Points

  • Bacterial overgrowth breath tests are a non-invasive method for diagnosing small intestinal bacterial overgrowth (SIBO), which can be accompanied by symptoms of bloating, stool changes, headaches, and skin disorders.
  • Breath tests don’t always correlate with SIBO symptoms and may not perfectly correspond with clinical recovery.
  • Other types of dysbiosis, such as hydrogen sulfide SIBO and small intestinal fungal overgrowth (SIFO), aren’t detected on standard methane and hydrogen breath tests, but can be picked up by newer tests like the TrioSmart breath test.
  • Breath tests might indicate some type of imbalance in the GI tract, and retesting after treatment may correlate with SIBO symptom improvement (but not always).
  • It may be best to seek out a bacterial overgrowth breath test and other types of digestive testing after you’ve implemented dietary and lifestyle changes, and supplements like probiotics.

If you’re struggling with symptoms like gas, bloating, stool changes, fatigue, and food sensitivities, you have likely stumbled across small intestinal bacterial overgrowth (SIBO) in your search for answers. 

However, pursuing a diagnosis of SIBO can be tricky, as the gold standard for testing is an invasive endoscopy. This makes the bacterial overgrowth breath test a top contender for diagnosing SIBO. Breath tests are moderately useful when interpreted properly and used at the right time. However, there are a few things to be cautious of: SIBO breath test results often don’t correlate with symptoms, can result in false positives, and may miss other types of imbalances in the gut microbiota. 

Due to these limitations, it may be best to skip the breath test as a first step in your recovery from SIBO-like symptoms — or at the very least, make sure you’re working with an experienced practitioner who can properly interpret your results (and doesn’t rely too heavily on them). 

While a bacterial overgrowth breath test can help guide your treatment options, and improvements in repeat testing may indicate symptom relief, it’s more beneficial to focus on treating your symptoms — not just normalizing labs. 

Fortunately, many people with symptoms of SIBO can benefit from dietary changes and targeted supplements, like probiotics and natural antimicrobials, without having to undergo a breath test first. These therapies are often helpful, whether you test positive for SIBO or not, and can save you some time and money otherwise spent on a breath test. 

But when all else fails, it may be time to recruit a healthcare provider and seek out a breath test or other type of dysbiosis testing. This can help you get to the root of your symptoms before moving on to other targeted SIBO treatments, like prescription antibiotics. Let’s dig into the details of bacterial overgrowth breath tests. 

Why You May Be Considering a Bacterial Overgrowth Breath Test

Small intestinal bacterial overgrowth, or SIBO, is well-recognized in the functional medicine community for contributing to a wide array of disruptive health symptoms. It’s believed to cause many digestive symptoms, including excessive gas, bloating, cramping, abdominal pain, reflux, and stool changes, like diarrhea and constipation [1]. 

Because of the numerous connections between the gut and other systems in the body, SIBO also tends to come with non-digestive symptoms, including:

  • Brain fog and headaches
  • Joint pain
  • Fatigue or low energy [1]
  • Weight loss due to malabsorption
  • Mood changes like depression and anxiety [1, 2, 3, 4]
  • Food sensitivities [1]
  • Carbohydrate, fructose, or lactose intolerance
  • Skin disorders, like rosacea [5]

Research supports that SIBO is also linked to a wide array of gastrointestinal disorders, like irritable bowel syndrome (IBS), Celiac disease, and Crohn’s disease [6, 7, 8, 9, 10]. It may even create or contribute to metabolic dysfunction, such as weight gain, and elevated blood sugar and lipids [11, 12, 13].

What Is a Bacterial Overgrowth Breath Test?

Technically a lab finding, not a health condition, SIBO can be detected through an at-home breath test [1]. For this particular diagnostic test, you drink a sugar solution consisting of either glucose or lactulose. Your breath samples are then collected at regular intervals over the course of about three hours and measured for methane and hydrogen gas. An excessive production of intestinal gasses is considered to be a positive result for SIBO [14].

But these bacterial overgrowth breath tests don’t always hit the mark and their validity can highly depend on your healthcare provider’s interpretation of the results. Let’s jump into the specifics of breath testing.

The Pitfalls of Bacterial Overgrowth Breath Tests

Unfortunately, a positive breath test doesn’t always mean symptomatic SIBO, and vice versa. I often see that patient symptoms don’t always correlate with bacterial overgrowth breath test results. Those with SIBO-like complaints may come back with a normal breath test, creating a lot of frustration for both the patient and practitioner. 

These “normal” results are possibly attributed to traditional breath tests missing other types of gut dysbiosis, or an imbalance in the gut flora. This may be the case in those who have hydrogen sulfide SIBO or SIBO’s close relative, small intestinal fungal overgrowth (SIFO), which can have nearly identical symptoms to SIBO. However, newer breath tests (discussed later on) can now detect hydrogen sulfide SIBO, lessening the inconsistency of having SIBO symptoms with normal test results. 

On the flipside, some patients may get positive SIBO test results and worry about their health — even when they’re not actually experiencing symptoms. While being proactive is a good thing, a positive SIBO breath test if you’re feeling well isn’t reason enough to be concerned. 

When SIBO Isn’t Really SIBO

Occasionally, these false positives that result in a diagnosis of small intestinal bacterial overgrowth are caused by faulty interpretation of test results. To understand how this occurs, we must touch upon the differences between the bacterial makeup of the large and small intestines. 

While a healthy small intestine typically has a smaller amount of gut flora, the large intestine has a robust gut microbiome. Since bacteria are what produce the gasses observed through breath tests, it’s quite normal — and even expected — to see hydrogen and methane levels rise when the sugar solution enters the colon. 

Unfortunately, well-intentioned practitioners may give a SIBO diagnosis when the amount of hydrogen rises above 20 ppm, or when methane levels increase to 10 ppm or higher, at any point during the test. But due to the differences in bacterial composition of the large and small bowel, a more accurate cut-off for a positive test result is prior to the 80- to 90-minute mark — the point at which the solution enters the large intestine [15].

However, as a quick caveat, if you have symptoms of SIBO and show gas elevations above baseline past the 90-minute mark, that doesn’t necessarily mean that you won’t benefit from SIBO treatment. For this reason (as we’ll discuss later), it’s best to focus on treating your symptoms, not your lab results.

Further adding to the breath test conundrum, those without any SIBO-related symptoms may test positive on a breath test [1]. While a glucose breath test (as opposed to a lactulose breath test) may protect against these false positive results [14], this isn’t always the case and a misdiagnosis can lead to fear, restrictive diets, and unnecessary treatment interventions, like antibiotics. 

Breath Tests Aren’t Always the Best Indicator of Recovery 

In some cases, an improvement in SIBO symptoms post-treatment isn’t always reflected on a bacterial overgrowth breath test. This discrepancy is highlighted by one of my own patient’s experiences with overcoming a diagnosis of SIBO. 

One Patient’s SIBO Success Story

Christine came to me, bedridden, with symptoms of severe daily headaches, chemical sensitivities, and lifelong constipation and bloating. Her breath test showed positive results for SIBO, and we began treatment immediately. 

Within a month of dietary and supplemental interventions, Christine’s headaches, sensitivities, and digestive symptoms had dissipated. As an added benefit, she experienced a desired 40-pound weight loss and was able to now tolerate daily activities that she couldn’t before, such as grocery shopping and having a social life. Christine was able to successfully reintroduce many foods back into her diet without backsliding, and she now “feels like she has a whole new life and better than she did as a teenager.” 

Curiously, while her breath test results had improved overall and she felt great, she still tested positive for SIBO. This mismatch between her lab results and resolution of symptoms is highly relevant and important. If we had relied solely on her test results to dictate whether she had completely recovered, her case could be considered a “fail.” 

Christine’s case highlights the importance of not over-relying on lab results when evaluating for a successful recovery. While bacterial overgrowth breath tests may be helpful in screening for SIBO and evaluating for improvements during treatment, the true measure of success should focus on improvement in patient symptoms. 

So is a bacterial overgrowth breath test always a bad idea? Not necessarily, and we’ll discuss the benefits of breath testing in our next section. 

When a Breath Test Should Be Your Next Step

Despite the limitations surrounding bacterial overgrowth breath tests, they’re still the most justifiable diagnostic tests for SIBO, as the gold standard, or “best method,” for detecting intestinal bacterial overgrowth is fairly invasive and inconvenient for most people. 

This inaccessible (but more accurate) method involves an endoscopic procedure. Jejunal aspirate testing assesses for bacterial overgrowth by sampling secretions from the small bowel. During this procedure, a gastroenterologist inserts a thin tube down the esophagus into the small intestine, where a sample of jejunal (a section of the small intestine) secretions are collected and analyzed for intestinal bacteria [14].

The Upside to Bacterial Overgrowth Breath Tests

As the above test is performed under general anesthesia, you can see why a bacterial overgrowth breath test is the “go-to” method for many functional medicine practitioners. Additionally, imbalances in gut bacteria are associated with poor digestive health and a myriad of chronic health conditions, making a bacterial overgrowth breath test an attractive option.

When properly interpreted, a positive breath test may indicate some type of imbalance in the microbiome, even if it’s not SIBO, and can be used to help guide treatment in those with persistent health symptoms. Furthermore, repeat breath tests (measured after treatment) are more likely to correspond with improvement in symptoms [1].

As previously mentioned, advancements in SIBO breath tests now have a way to pick up on hydrogen sulfide SIBO that traditional breath tests miss [16, 17]. The TrioSmart breath test may actually detect all three known types of SIBO [18]:

  • Hydrogen
  • Methane 
  • Hydrogen sulfide 

Unfortunately, there’s still no practical method or breath test for detecting fungal overgrowths in the small intestine.

When to Try Out the SIBO Breath Test (and Other Types of Testing)

While switching to a new diet (such as the low FODMAP diet) and trying out probiotics and natural antimicrobials can often relieve symptoms of SIBO — whether you’ve had a positive breath test or not — they may not work for everyone. If this is the case and you haven’t had a SIBO breath test yet, it might be time to seek out the guidance of a healthcare provider who’s knowledgeable in interpreting breath tests and isn’t overly reliant on the results. 

Breath tests and other types of dysbiosis testing are useful in these cases, as they can help guide your treatment. For instance, it probably isn’t best to use certain SIBO therapies, like prescription antibiotics, without having a positive breath test first. 

Breath tests may not be perfect, but their limitations aren’t to dissuade you from getting help for your digestive complaints and other persistent health concerns. SIBO breath testing may be especially helpful for those with chronic gut disorders, like IBS or inflammatory bowel disease, particularly if they’ve had limited results with conventional or alternative treatments. 

To sum it up, if you have SIBO-like symptoms you’ll likely benefit from “DIY” treatments without having to undergo prior testing first, saving you a lot of time, energy, and money. However, when nothing seems to help, it’s probably time to find a provider familiar with breath tests and other types of dysbiosis testing. This will help you get to the bottom of your symptoms to see if SIBO or another type of gut flora imbalance is to blame.

Is a Bacterial Overgrowth Breath Test Really Worth It? - Your%20SIBO%20Treatment%20Plan 01 L

The Verdict on Bacterial Overgrowth Breath Tests 

In some cases, it may be best to skip the breath test as a first step when addressing your digestive health concerns. While many providers prefer a SIBO breath test over jejunal secretion sampling due to its ease and accessibility, it comes with its own set of limitations.

Traditional bacterial overgrowth breath tests can miss other types of intestinal dysbiosis, including hydrogen sulfide SIBO and SIFO. More importantly, when bacterial overgrowth breath test results are prioritized over patient symptoms, those with no symptoms may be subjected to unnecessary interventions, fear, and restrictive diets. 

However, when dietary changes, lifestyle modifications, and certain supplements (such as probiotics) fail to give you relief, a breath test may come in handy for determining if SIBO or another form of dysbiosis is behind your chronic health symptoms. 

I recommend following my simple protocol, outlined in my book Healthy Gut, Healthy You, to get you started on treating your digestive symptoms and other health concerns. If you would like assistance in your health journey, we have several SIBO-fluent healthcare providers at our functional medicine clinic

The Ruscio Institute has developed a range of high-quality formulations to help our patients and audience. If you’re interested in learning more about these products, please click here. Note that there are many other options available, and we encourage you to research which products may be right for you.

➕ References
  1. Ruscio M. Is SIBO A real condition? Altern Ther Health Med. 2019 Sep;25(5):30–8. PMID: 31550680.
  2. Ng QX, Peters C, Ho CYX, Lim DY, Yeo W-S. A meta-analysis of the use of probiotics to alleviate depressive symptoms. J Affect Disord. 2018 Mar 1;228:13–9. DOI: 10.1016/j.jad.2017.11.063. PMID: 29197739.
  3. Huang R, Wang K, Hu J. Effect of Probiotics on Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Nutrients. 2016 Aug 6;8(8). DOI: 10.3390/nu8080483. PMID: 27509521. PMCID: PMC4997396.
  4. Akkasheh G, Kashani-Poor Z, Tajabadi-Ebrahimi M, Jafari P, Akbari H, Taghizadeh M, et al. Clinical and metabolic response to probiotic administration in patients with major depressive disorder: A randomized, double-blind, placebo-controlled trial. Nutrition. 2016 Mar;32(3):315–20. DOI: 10.1016/j.nut.2015.09.003. PMID: 26706022.
  5. Parodi A, Paolino S, Greco A, Drago F, Mansi C, Rebora A, et al. Small intestinal bacterial overgrowth in rosacea: clinical effectiveness of its eradication. Clin Gastroenterol Hepatol. 2008 Jul;6(7):759–64. DOI: 10.1016/j.cgh.2008.02.054. PMID: 18456568.
  6. Schmulson M, Bielsa MV, Carmona-Sánchez R, Hernández A, López-Colombo A, López Vidal Y, et al. Microbiota, gastrointestinal infections, low-grade inflammation, and antibiotic therapy in irritable bowel syndrome: an evidence-based review. Rev Gastroenterol Mex. 2014 Jun;79(2):96–134. DOI: 10.1016/j.rgmx.2014.01.004. PMID: 24857420.
  7. Takakura W, Pimentel M. Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome – An Update. Front Psychiatry. 2020 Jul 10;11:664. DOI: 10.3389/fpsyt.2020.00664. PMID: 32754068. PMCID: PMC7366247.
  8. Pimentel M, Wallace D, Hallegua D, Chow E, Kong Y, Park S, et al. A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing. Ann Rheum Dis. 2004 Apr;63(4):450–2. DOI: 10.1136/ard.2003.011502. PMID: 15020342. PMCID: PMC1754959.
  9. Tursi A, Brandimarte G, Giorgetti G. High prevalence of small intestinal bacterial overgrowth in celiac patients with persistence of gastrointestinal symptoms after gluten withdrawal. Am J Gastroenterol. 2003 Apr;98(4):839–43. DOI: 10.1111/j.1572-0241.2003.07379.x. PMID: 12738465.
  10. Shah A, Morrison M, Burger D, Martin N, Rich J, Jones M, et al. Systematic review with meta-analysis: the prevalence of small intestinal bacterial overgrowth in inflammatory bowel disease. Aliment Pharmacol Ther. 2019 Mar;49(6):624–35. DOI: 10.1111/apt.15133. PMID: 30735254.
  11. Mathur R, Chua KS, Mamelak M, Morales W, Barlow GM, Thomas R, et al. Metabolic effects of eradicating breath methane using antibiotics in prediabetic subjects with obesity. Obesity (Silver Spring). 2016 Mar;24(3):576–82. DOI: 10.1002/oby.21385. PMID: 26833719. PMCID: PMC4769647.
  12. Basseri RJ, Basseri B, Pimentel M, Chong K, Youdim A, Low K, et al. Intestinal methane production in obese individuals is associated with a higher body mass index. Gastroenterol Hepatol (N Y). 2012 Jan;8(1):22–8. PMID: 22347829. PMCID: PMC3277195.
  13. Mathur R, Amichai M, Chua KS, Mirocha J, Barlow GM, Pimentel M. Methane and hydrogen positivity on breath test is associated with greater body mass index and body fat. J Clin Endocrinol Metab. 2013 Apr;98(4):E698-702. DOI: 10.1210/jc.2012-3144. PMID: 23533244. PMCID: PMC3615195.
  14. Losurdo G, Leandro G, Ierardi E, Perri F, Barone M, Principi M, et al. Breath Tests for the Non-invasive Diagnosis of Small Intestinal Bacterial Overgrowth: A Systematic Review With Meta-analysis. J Neurogastroenterol Motil. 2020 Jan 30;26(1):16–28. DOI: 10.5056/jnm19113. PMID: 31743632. PMCID: PMC6955189.
  15. Rezaie A, Buresi M, Lembo A, Lin H, McCallum R, Rao S, et al. Hydrogen and Methane-Based Breath Testing in Gastrointestinal Disorders: The North American Consensus. Am J Gastroenterol. 2017 May;112(5):775–84. DOI: 10.1038/ajg.2017.46. PMID: 28323273. PMCID: PMC5418558.
  16. Singer-Englar T, Rezaie A, Gupta K, Pichetshote N, Sedighi R, Lin E, et al. Sa1219 – Validation of a 4-Gas Device for Breath Testing in the Determination of Small Intestinal Bacterial Overgrowth. Gastroenterology. 2018 May;154(6):S-281. DOI: 10.1016/S0016-5085(18)31300-3.
  17. Guo HZ, Dong WX, Zhang X, Zhu SW, Liu ZJ, Duan LP. [The diagnostic value of hydrogen sulfide breath test for small intestinal bacterial overgrowth]. Zhonghua Nei Ke Za Zhi. 2021 Apr 1;60(4):356–61. DOI: 10.3760/cma.j.cn112138-20200731-00725. PMID: 33765706.
  18. Gemelli Biotech | Unlocking the Potential of the Microbiome [Internet]. Available from:

Need help or would like to learn more?
View Dr. Ruscio’s, DC additional resources

Get Help


I care about answering your questions and sharing my knowledge with you. Leave a comment or connect with me on social media asking any health question you may have and I just might incorporate it into our next listener questions podcast episode just for you!