Frequently Asked Questions

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→ General Information
→ Diagnosis & Testing
→ Causes and Risk Factors
→ Treatment Options
→ Diet and Lifestyle
→ Managing SIBO Relapse
→ SIBO and Other Conditions

General Information

  • An overgrowth of bacteria in the small intestine. These ‘disruptor’ bacteria create excessive gas and lead to a multitude of uncomfortable symptoms.

  • Bloating is the most common symptom for SIBO patients, as the bacterial overgrowth produces gas that can get trapped in the small intestine. Other symptoms include weight changes, flatulence, diarrhea, constipation, brain fog and fatigue.

  • SIBO is a subgroup of IBS characterized by bacterial overgrowth in the small intestine. Recent studies have found that up to 78% of IBS patients- as many as 30 million Americans- have SIBO.

  • It can be useful to categorize SIBO by the major gases the overgrowth produces. This gives valuable insight into the strains of bacteria or archaea that are colonizing the small intestine. Antibiotic therapy can be tailored to target the specific strains if known. Additionally, there are different symptom profiles associated with each type. For example, methane dominant SIBO, or IMO, tends to cause constipation.

  • The gut microbiome refers to the microbes in the gut. This includes bacteria, fungi, viruses, and archaea (single cell organisms similar to bacteria). Gut motility refers to the coordinated movement of the gut to move food through the digestive system. SIBO remission refers to the end goal of treatment to achieve relief from symptoms allowing you to return to a normal lifestyle.

  • SIBO is not a standalone condition but rather a secondary disorder arising from other underlying diseases, structural abnormalities in the digestive system, or external triggers. Anything that disrupts gut motility, impairs digestion, or weakens the body’s ability to regulate bacteria can contribute to SIBO. Some of the most common factors known to cause SIBO can be found on our Root Causes page. description

  • No, SIBO is not contagious, however some of the underlying conditions, for example norovirus food poisoning, may be considered contagious.

  • Estimates vary but one retrospective study found that 33.8% of patients that underwent breath testing after reporting gastrointestinal distress had SIBO.

Diagnosis and Testing

  • SIBO may be diagnosed using information about your symptoms, duodenal/jejunal aspiration testing, and/or breath testing.

  • A SIBO breath test measures levels of exhaled gases. Raised levels of gases immediately after eating indicate an overgrowth of bacteria in the small intestine.

  • It can be useful to categorize SIBO by the major gases produced as this gives valuable insight into the strains of bacteria or archaea that are colonizing the small intestine. Antibiotic therapy can be tailored to target the specific strains if known. Additionally, there are different symptom profiles associated with each, for example methane dominant SIBO, or IMO, tends to present more alongside constipation.

  • There are reports of false negative results in both breath testing and aspirate testing, for this reason it is important to share your symptoms with your care team.

  • The best place to begin is by speaking with your primary care doctor and existing GI doctor about your symptoms and the possibility of SIBO. They may be able to recommend a specialist to you.

Causes & Risk Factors

  • Yes, food poisoning can create the opportunity for bacteria to overgrow in the small intestine. This is known as postinfectious IBS.

  • Other gastrointestinal diseases, such as Intestinal Bowel Disease (Crohn’s, Ulcerative Colitis), Celiac Disease, and gastric paresis may cause inflammation and impair git motility creating an ideal environment for SIBO.

  • Gut motility helps keep food, bacteria, and bile acids moving through the gastrointestinal system at a regular pace. When motility is impaired food and bacteria can sit in the small intestine where the bacteria will flourish, producing gas and other uncomfortable symptoms of SIBO.

  • There is certainly communication between the gut and the brain, known as the gut-brain axis. However, there is no data to suggest that stress or mental health disorders play a role in developing SIBO. There is evidence to suggest that the reverse may be true, that the gut microbiome can influence brain function. Research into the gut-brain axis is ongoing.

  • SIBO may aggravate leaky gut syndrome by increasing inflammation in the gastrointestinal tract.

Treatment Options

  • Treatment for SIBO is done in two phases. The first phase aims to eliminate the bacterial overgrowth, typically involving a 2-3 week elemental diet, antibiotics, or a combination of both. Multiple treatment cycles may be needed before achieving lasting symptom relief (remission) depending on the case. The second phase is maintenance of remission, involving dietary and lifestyle changes and sometimes additional medications to prevent SIBO from recurring.

  • There are many antibiotics that can be used to treat SIBO. The most common is Rifaxamin, but the type of antibiotic used for treatment varies and will be determined by your doctor on a case by case basis.

  • Herbal remedies have yet to be proven in clinical studies and are therefore not widely implemented, but there are promising reports from patients who have used herbal remedies for SIBO.

  • An elemental diet is a liquid form of nutrition in its most basic form. This allows for your nutrition to be absorbed in the first 2-4 feet of the small intestine, giving the rest of your gut a rest from active digestion and cutting the offending bacteria in the rest of the small intestine off from its nutritional source. Elemental Diets have been proven to be 83% effective in eradicating SIBO, as evaluated by breath testing. Patient compliance has historically been an issue with elemental diets, however recent advancements have created a palatable elemental diet resolving this issue.

  • Length of SIBO treatment varies depending on the underlying cause of SIBO and severity.

  • Probiotics are a common tool used for gastrointestinal distress, but may not be a good fit in the case of SIBO. Probiotics aim to increase bacteria growth, while the aim of SIBO treatment is typically to reduce overgrowth.

  • Prokinetics are medications that encourage gut motility. Regular movement of food through the digestive system can help prevent SIBO relapse by clearing food and bacteria out of the small intestine minimizing build up.

  • SIBO can be treated but relapse is seen in up to 44% of cases within 9 months of achieving remission (reduction of symptoms and signs of SIBO). Please see our treatment page for advice on maintaining remission.

  • Severe cases of SIBO have been associated with malabsorption leading to malnutrition and nutritional deficiencies. These complications can include rosacea, anemia, metabolic bone disease and more.

Diet and Lifestyle

  • Low Fermentation Eating (LFE) is a dietary plan for SIBO and IBS patients. The goal of LFE is to encourage regular gut cleansing waves and reduce intake of highly fermentable foods. This two pronged approach normalizes the environment of the small intestine making it less favorable for bacteria growth. LFE is minimally restrictive and nutritionally stable.

  • The Low FODMAP diet restricts the intake of highly fermentable carbohydrates: Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols (FODMAPs). These foods can act as a nutritional source for bacteria in SIBO as they are difficult to digest, so the bacteria in your gut are able to digest them producing gas in a process called fermentation. Fermentation produces gas and encourages bacteria growth, which aggravates SIBO symptoms.

  • Fermented foods are generally not recommended for SIBO as their probiotic and prebiotic properties may negatively impact SIBO.

  • Yes, meal spacing and an 8 hour overnight fasting period are the first pillar of Low Fermentation Eating, a plan developed by clinicians at Cedars-Sinai for the management of SIBO and IBS. LFE stresses the importance of allowing 4-5 hours between meals to work with the migrating motor complex and allow the gut to process its normal cleansing waves to keep food from fermenting in the small intestine.

  • It is best to speak with your healthcare provider before making any dietary changes, as they will best be able to determine what modifications are best on an individual basis. However, there are some foods that are most commonly known to affect SIBO patients negatively. These foods are typically difficult to digest and highly fermentable, meaning they are great food sources for bacteria.

  • Exercise is key to maintaining overall health, and certainly plays a part in aiding digestion. How exercise specifically plays a part in SIBO specifically has yet to be extensively researched.

  • SIBO may affect sleep health by causing excess fatigue. A small study found that IBS and SIBO were common among restless leg syndrome patients.

Managing SIBO Relapse

  • SIBO can be difficult to eliminate, particularly if the underlying cause of the bacterial overgrowth cannot be found or modified. In these cases, often structural issues or motility problems that cannot be resolved, bacteria can overgrow again after treatment since the environment in the small intestine is still favorable for bacterial growth.

  • There are medical, dietary, and lifestyle interventions that can help extend periods between SIBO flares, ideally indefinitely though this is not always possible. In some cases, multiple rounds of treatment may be needed.

  • Prokinetics, dietary modifications, and lifestyle changes can all be used to manage SIBO long term. It is best to consult with your doctor about which strategies are the best for your situation.

  • Yes, maintenance diets such as Low Fermentation Eating (LFE) and Low FODMAP can be used to keep SIBO from returning. For more details please see our Treating SIBO page.

  • If your symptoms return after treatment please speak with your doctor. Additional rounds of treatment may be needed to eliminate SIBO, especially if gut motility is impaired.

SIBO & Other Conditions

  • Yes, SIBO has been associated with weight loss and malabsorption of nutrients.

  • Long term use of PPIs for the management of GERD has been shown to cause changes in the gut microbiome, sometimes leading to SIBO. One study on patients undergoing anti-reflux surgery found that 60.6% had intestinal dysbiosis (SIBO and IMO).

  • Dysbiosis and gut inflammation have long been linked to mental health issues via the gut-brain axis. The relationship between the two has been historically viewed as cause and effect, that stress may lead to gut issues such as SIBO. However, recent research has begun to look at how gut issues may lead to stress. A preliminary study on SIBO patients found that they had higher situational anxiety and stress levels than the non-SIBO group.

  • Chronic inflammation from SIBO may cause skin issues, like rosacea. One study found that there was a high prevalence of SIBO in rosacea patients and that when SIBO was eradicated with antibiotic treatment, clinical improvement in rosacea was also seen.

  • SIBO has been associated with hypothyroidism, given that low thyroid activity can cause low motility in the gut. This slowing of the gastrointestinal system can allow bacteria to thrive in the small intestine.

  • SIBO can lead to sensitivity to harder to digest foods, such as dairy products containing lactose, sugar alcohols, fiber, and FODMAPs.

  • Some gut microbiota produce histamine as a digestive output. There may be overlap in an excess of histamine producing bacteria and SIBO. One study found that SIBO is common in mast cell activation syndrome patients.

  • Inflammation and nutrient deficiencies from SIBO may impact hormone production.

  • SIBO may trigger a response from the immune system, which could exacerbate symptoms in patients with a preexisting autoimmune disease.

Sources:

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  3. Weinstock LB, Walters AS. Restless legs syndrome is associated with irritable bowel syndrome and small intestinal bacterial overgrowth. Sleep Med. 2011 Jun;12(6):610-3. doi: 10.1016/j.sleep.2011.03.007. Epub 2011 May 13. PMID: 21570907.

  4. Haworth, J.J., Boyle, N., Vales, A. et al. The prevalence of intestinal dysbiosis in patients referred for antireflux surgery. Surg Endosc 35, 7112–7119 (2021). https://doi.org/10.1007/s00464-020-08229-5

  5. Clapp M, Aurora N, Herrera L, Bhatia M, Wilen E, Wakefield S. Gut microbiota's effect on mental health: The gut-brain axis. Clin Pract. 2017 Sep 15;7(4):987. doi: 10.4081/cp.2017.987. PMID: 29071061; PMCID: PMC5641835.

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