Understanding SIBO: Symptoms, Causes, Testing, and Treatment Options
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If you've been dealing with persistent bloating, gas, or unexplained digestive issues, you may have come across the term SIBO—short for Small Intestinal Bacterial Overgrowth.
SIBO is increasingly recognized as a common (and often overlooked) cause of chronic gut symptoms. In this guide, we'll break down what SIBO is, its symptoms, how it's diagnosed, and the most effective treatment options available.
What Is SIBO?
Small Intestinal Bacterial Overgrowth (SIBO) occurs when too many bacteria accumulate in the small intestine.
While your large intestine is designed to house a large population of bacteria that help with digestion, your small intestine is not. When bacteria migrate upward or grow excessively in this area, they can disrupt digestion, interfere with nutrient absorption, and produce uncomfortable symptoms.
SIBO Symptoms: What to Watch For
One of the biggest challenges with SIBO is that its symptoms often mimic other digestive conditions—especially IBS (Irritable Bowel Syndrome).
Common SIBO symptoms include:
- Bloating (often worse as the day goes on)
- Excessive gas and flatulence
- Abdominal pain or cramping
- Diarrhea, constipation, or alternating between both
- Nausea
- Unexplained weight loss
- Nutrient deficiencies (such as vitamin B12 or iron)
If these symptoms feel familiar and persistent, it may be worth exploring SIBO testing.
How Is SIBO Diagnosed?
Because SIBO symptoms overlap with many other gut conditions, proper testing is key.
1. SIBO Breath Test (Most Common)
The SIBO breath test is the most widely used, non-invasive diagnostic tool.
You'll drink a sugar solution (typically glucose or lactulose), and over the next 2–3 hours, breath samples are collected. If excess bacteria are present, they ferment the sugar and release gases like hydrogen or methane, which show up in your breath.
Preparation usually involves:
- A low-fermentation diet for 24 hours
- Avoiding fiber, sugars, and complex carbohydrates
- Fasting before the test
You can access SIBO breath testing through a gastroenterologist, functional medicine provider, or even at-home kits.
2. Small Intestinal Aspirate (Less Common)
This is a more invasive but direct test, involving an endoscopy to collect fluid from the small intestine.
While it can be more precise, it's used less often due to cost, invasiveness, and the risk of contamination.
SIBO Treatment: What Actually Works?
Treating SIBO isn't just about killing bacteria—it's about addressing the root cause and preventing recurrence.
Here are the main approaches:
1. Antibiotics for SIBO
The most common medical treatment is targeted antibiotics such as rifaximin.
These are designed to reduce bacterial overgrowth with minimal systemic absorption. However, they can be expensive, and insurance coverage varies. Other antibiotics may be used but sometimes come with more side effects.
2. Herbal Antimicrobials
For those looking for a more natural or cost-effective option, herbal antimicrobials are commonly used.
Popular options include:
- Berberine (from goldenseal, barberry, Oregon grape)
- Oil of oregano
- Allicin (garlic extract, often used for methane-dominant SIBO)
Some studies suggest these may be comparable to antibiotics in certain cases, though guidance from a practitioner is important.
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Sometimes people experience "die-off" symptoms when treating SIBO. OrthoMolecular SBI Protect is a popular product that can be used to improve gut barrier integrity, as well as symptoms like diarrhea and bloating. It also comes in powder form. This supplement can be used during the treatment phase and beyond.
3. Prokinetic Agents
These medications are sometimes used after (or during) treatment to stimulate the "migrating motor complex" - the guts natural wave,-like sweeping motion that keeps food and bacteria moving through the small intestine. The helps bacteria from stagnating and regrowing.
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4. The SIBO Diet (Low-FODMAP & Beyond)
Diet plays a major role in symptom management.
A low-FODMAP diet or low-fermentation diet is often recommended to reduce bacterial fermentation and ease symptoms during treatment.
Probiotics: Some probiotics mayhelp symptoms, but the wrong kind could hurt. It is important that one uses soil based or spore forming probiotics, saccaromyces boulardii (a yeast), or certain lactobacillus or bifidobacterium blends. Choosing the correct type matter, so it is important to work with a healthcare practitioner.
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Important Information
*Contents in this article are not to replace recommendations from your physician. It is recommended that one consults with their doctor before starting any new supplements. Supplements linked in this article have not been evaluated by the Food and Drug Administration. The products mentioned are not intended to diagnose, treat, cure, or prevent any disease
Sources:
- Adike A, et al. Small intestinal bacterial overgrowth: Nutritional implications, diagnosis, and management. Gastroenterological Clinics of North America. 2018; doi:10.1016/j.gtc.2017.09.008.
- Ferri FF. Small bowel bacterial overgrowth (SIBO). In: Ferri's Clinical Advisor 2020. Elsevier; 2020. https://www.clinicalkey.com. Accessed Jan. 17, 2020.
- Velasco-Aburto S, Llama-Palacios A, Sánchez MC, Ciudad MJ, Collado L. Nutritional Approach to Small Intestinal Bacterial Overgrowth: A Narrative Review. Nutrients. 2025 Apr 23;17(9):1410. doi: 10.3390/nu17091410. PMID: 40362719; PMCID: PMC12073203.
- Velasco-Aburto, S., Llama-Palacios, A., Sánchez, M. C., Ciudad, M. J., & Collado, L. (2025). Nutritional Approach to Small Intestinal Bacterial Overgrowth: A Narrative Review. Nutrients, 17(9), 1410. https://doi.org/10.3390/nu17091410
- Martyniak A, Wójcicka M, Rogatko I, Piskorz T, Tomasik PJ. A Comprehensive Review of the Usefulness of Prebiotics, Probiotics, and Postbiotics in the Diagnosis and Treatment of Small Intestine Bacterial Overgrowth. Microorganisms. 2025 Jan 1;13(1):57. doi: 10.3390/microorganisms13010057. PMID: 39858825; PMCID: PMC11768010.