SIBO: 12 Causes, Symptoms, Treatment, Diet, and Prevention

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Living with small intestinal bacterial overgrowth (SIBO) may significantly decrease your quality of life and is more prevalent than experts previously believed. SIBO is estimated to impact up to 15% of healthy individuals, often without their awareness of its presence.

SIBO may be caused by irritable bowel syndrome (IBS), hypothyroidism, or a whole host of other medical conditions. SIBO can also be an underlying condition that triggers other diseases.

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What Is SIBO?

Most of your gut bacteria should be growing in your large intestine. SIBO occurs when excess bacteria is growing in your small intestine instead. This can lead to malnutrition or other gastrointestinal tract disorders, such as IBS. A majority of IBS patients also have SIBO. 

A bacterial overgrowth can break down undigested food in your small intestine, which produces hydrogen. That hydrogen may feed other small organisms in your small intestine and produce methane. The excess hydrogen, methane, or both, then gets trapped in your digestive tract.

Treating SIBO often reverses IBS permanently, especially when combined with other IBS-healing strategies.

Here at PrimeHealth, when we treat someone for IBS, we test for SIBO. The test often comes back positive. If you’re in Denver and suffering from gut issues, our team of functional doctors would love to help you cure them at the root cause.

What Causes SIBO?

There are several ways SIBO develops in the gut. The root cause of SIBO is a complex and controversial topic. Because there are multiple separate underlying conditions that can lead to SIBO, conventional doctors may say the cause of SIBO is unknown.

Investigating, diagnosing, and treating the underlying condition at the root cause of your SIBO can effectively cure you. For that reason, we know that there is a cure; you just have to find a doctor willing to find it. 

Medical conditions that may trigger or be associated with SIBO include:

  1. Hypothyroidism
  2. Cirrhosis of the liver
  3. Diabetes
  4. Scleroderma
  5. Celiac disease
  6. Fibromyalgia
  8. Parkinson’s disease
  9. Small bowel diverticulosis
  10. Crohn’s disease
  11. Ulcerative colitis
  12. Irritable bowel syndrome

5 risk factors that increase your risk of SIBO include:

  1. Old age
  2. Female gender
  3. Alcohol use
  4. Previous bowel surgery
  5. Certain medications, such as antibiotics or proton pump inhibitors

SIBO Symptoms

SIBO may cause or be caused by IBS. This is why SIBO and IBS share so many symptoms. Common symptoms of SIBO include:

  • Abdominal pain
  • Bloating
  • Cramping
  • Stomach growling
  • Flatulence
  • Diarrhea
  • Constipation
  • Nausea
  • Nutritional deficiency
  • Fat malabsorption
  • Weight loss
  • Fatigue
  • Rash
  • Joint pain
  • Asthma
  • Skin conditions, such as acne, eczema, rosacea

Call your doctor right away if you experience SIBO symptoms such as trouble breathing, unusual food cravings, or pale skin. This may indicate your SIBO has caused malnutrition, which may be life-threatening.

Read Next: Stomach Growling and Bowel Cancer 

How to Diagnose SIBO

A primary care doctor or a specialist, such as a gastroenterologist, may diagnose SIBO using several methods, including a breath test. Here at PrimeHealth, we always run SIBO breath tests when diagnosing IBS. Up to 84% of IBS patients test positive for SIBO.

Glucose, xylose, and lactulose breath tests are less invasive diagnostics than blood tests and produce reliable test results for SIBO. 

The results of the breath tests indicate one of 2 things:

  • A methane-positive breath test usually indicates constipation-dominant IBS. (IBS-C)
  • A hydrogen-positive breath test usually indicates diarrhea-dominant IBS. (IBS-D)

Other ways to diagnose SIBO include:

  • Symptoms checklist
  • Physical examination
  • Personal medical history
  • Family medical history
  • Blood testing
  • Urine testing
  • Comprehensive stool testing

SIBO Treatment Options

Curing SIBO can only happen by diagnosing and treating the root cause of the bacterial overgrowth. However, there are still steps to treat bacterial overgrowth in the small intestine. 

3 steps to treat SIBO are:

  1. Reduce small intestine bacterial overgrowth
  2. Restore gut motility
  3. Repopulate good bacteria

Although your small intestine is naturally home to some bacteria, most bacteria should be living in your large intestine.

Can SIBO go away on its own? No, SIBO needs to be treated to go away. That being said, you may unintentionally treat SIBO if you change your diet, switch out medications, or start to exercise regularly.


We prefer to keep pharmaceuticals to a minimum. They can be overused and often come with adverse side effects, so they should be used strategically. 

Medications we may prescribe for SIBO include:

  • Prucalopride (Motegrity) and low-dose naltrexone: These are promotility agents used to treat IBS-C and SIBO. It is important to restore gut motility to reduce small intestine overgrowth and get beneficial bacteria down to your large intestine. Both of these medications are prescribed for “off-label” treatment of SIBO or IBS.
  • Rifaximin: This is the generic of Xifaxan, an FDA-approved antibiotic to treat IBS-D. Rifaximin seems to treat SIBO effectively. (While several insurance companies don’t want to pay its high price tag, PrimeHealth uses pharmacies in Canada to obtain the generic form at a reasonable price.)
  • Prokinetics: This medication helps strengthen the lower esophageal sphincter and helps control acid reflux. A 2018 study showed that prokinetics enhanced gut motility and reduced the risk of SIBO in patients taking proton pump inhibitors.
  • Neomycin: This medication is an antibiotic we may use for methane-dominant SIBO. 
  • Antispasmodics: This medication helps relieve cramping. It may also cause constipation, so antispasmodics are usually only for hydrogen-dominant SIBO patients.

Even though we don’t often prescribe it, another antibiotic you may hear about for the treatment of SIBO is Metronidazole.

Bacteria may form a protective biofilm that is resistant to antibiotics. For this reason, we may suggest biofilm disruptors, such as systemic enzymes (ie: Interfase Plus). A biofilm disruptor helps to neutralize the bacteria’s defenses and leave the bacteria vulnerable.

A 2014 study concluded that certain herbal blends were as effective as Rifaximin in treating SIBO. For some SIBO sufferers, the all-natural route is the preferred route.

Dietary Supplements & Probiotics

Oil of oregano and allicin may treat SIBO. Certain herbal blends, like Dysbiocide or FC-cidal, may also treat SIBO.

Usually, probiotics are not ideal for correcting this overgrowth. Probiotics are supposed to repopulate your gut with beneficial bacteria. If you have an overgrowth in your small intestine, probiotics may populate in your small intestine, making the problem worse.

You will need to repopulate your beneficial bacteria after the overgrowth is taken care of. However, until you fully understand which probiotics help SIBO and which do not, you probably shouldn’t use probiotics until after your SIBO is reversed.

Probiotics for treating SIBO is a very nuanced topic, as certain strains of probiotics may counteract SIBO symptoms even better than antibiotics. This nuance can best be approached with a holistic provider like ours at PrimeHealth. 

SIBO Diets

We suggest the same diet for SIBO as we do for IBS: the low-FODMAP diet.

The most common SIBO diet is the low-FODMAP diet, or some less restrictive version of it (like Whole30). The low-FODMAP diet starves the harmful bacteria in your gut of fermentable carbs it needs, including if the overgrowth is in your small intestine (SIBO).

FODMAP stands for “fermentable oligosaccharides, disaccharides, monosaccharides and polyols.” Simply put, a FODMAP is a carbohydrate that can be fermented. Avoiding FODMAPs makes it harder for harmful bacteria to thrive in your small intestine.

A SIBO diet still includes:

  • Lean proteins
  • Healthy fats
  • Non-starchy vegetables
  • Leafy greens
  • Fruit, in moderation

However, this diet may not be right for all SIBO patients. The low-FODMAP diet is not recommended while treating SIBO with antibiotics. These antibiotics are more effective when you eat foods containing FODMAPs.

It may also be wise to cut out food allergens (wheat, dairy, alcohol, etc.) that may be causing gut health problems. 

Alcohol can be a trigger for many with SIBO. So if you’re planning to indulge, definitely check use ZBiotics® Pre-Alcohol™ Probiotic Drink first. For 10% off, use promo code PRIME at checkout.

How to Prevent SIBO

SIBO may recur if you do not permanently change your diet or lifestyle. Following these 4 prevention tips can help you keep your gut healthy.

4 tips for preventing SIBO:

  • Avoid added sugar and refined carbs
  • Lay off the probiotics if they worsen symptoms
  • Reduce daily stress
  • Exercise regularly

The key to preventing SIBO relapse is ensuring that gut motility is restored. If a certain medical condition is the underlying cause of your SIBO, treating your root condition may help resolve SIBO for good.


What are the first signs of SIBO?

The first signs of SIBO often include bloating, abdominal pain, and changes in bowel habits, such as diarrhea or constipation. If left unaddressed, SIBO can lead to nutritional deficiencies, unintended weight loss, and systemic symptoms like joint pain and fatigue.

How can I know if I have SIBO?

To know if you have SIBO, consult your healthcare provider who may recommend diagnostic procedures like endoscopy and the hydrogen breath test, especially if you are experiencing symptoms resembling inflammatory bowel disease. 

What’s happening in my gut with SIBO?

SIBO involves an overgrowth of bacteria in the small intestine, leading to increased fermentation of undigested carbohydrates like lactose. This can be influenced by factors such as the number of bacteria, reduced stomach acid, and impaired digestive secretions.

What does SIBO stool look like?

Stool changes in SIBO can vary, with individuals experiencing diarrhea, constipation, or a combination. The appearance may range from loose and watery to pellet-like, depending on the predominant symptom.

Does SIBO cause fistulas?

Fistulas are abnormal connections between body parts, and they can sometimes occur in association with conditions that cause inflammation, including SIBO.

What foods trigger SIBO?

Foods high in fermentable carbohydrates, such as certain fruits, vegetables, and grains, can trigger SIBO symptoms by promoting bacterial overgrowth in the small intestine. Limiting these fermentable foods, often referred to as the FODMAPs, might help SIBO-related symptoms.

Is there a test for SIBO?

Yes, a breath test is commonly used to diagnose SIBO. It measures the gases produced by bacteria in the small intestine after the ingestion of a substrate, helping to identify bacterial overgrowth.

Long-Term Prognosis

If SIBO goes untreated, it can lead to complications. These complications may greatly reduce your quality of life and, in rare cases, become life-threatening.

Complications of untreated SIBO:

  • Irritable bowel syndrome
  • Malnutrition
  • Dehydration
  • Neuropathy
  • Leaky gut syndrome
  • Vitamin deficiency
  • Night blindness (vitamin A deficiency)
  • Soft bones or tetany (vitamin D deficiency)
  • Slower blood clotting (vitamin K deficiency)
  • Anemia or fatigue (vitamin B12 deficiency)

Because SIBO can affect your gut microbiome (the balance of beneficial bacteria in your gut), SIBO may indirectly affect your immune system. 

Much of your immune system exists in your gut and relies on beneficial bacteria to protect it. SIBO may lead to increased harmful bacteria, followed by immune dysfunction.

SIBO (small intestinal bacterial overgrowth) is a relatively common problem in adults. It can be triggered by hypothyroidism, antibiotic overuse, diabetes, and more. 

SIBO may cause IBS, malnutrition, or vitamin deficiencies.

Effective SIBO treatments — including prescription drugs and all-natural options — may offer you a chance to reclaim your quality of life.

If you are in Colorado and struggling with signs of SIBO or other gut imbalances, schedule a free consultation with PrimeHealth today! You can work directly with our providers to reset your gut and restore your health.


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  2. Chedid, V., Dhalla, S., Clarke, J. O., Roland, B. C., Dunbar, K. B., Koh, J., … & Mullin, G. E. (2014). Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth. Global Advances in Health and Medicine, 3(3), 16-24.
  3. Soifer, L. O., Peralta, D., Dima, G., & Besasso, H. (2010). Comparative clinical efficacy of a probiotic vs. an antibiotic in the treatment of patients with intestinal bacterial overgrowth and chronic abdominal functional distension: a pilot study. Acta gastroenterologica Latinoamericana, 40(4), 323-327.
  4. Pimentel, M., Morales, W., Rezaie, A., Marsh, E., Lembo, A., Mirocha, J., … & Barlow, G. M. (2015). Development and validation of a biomarker for diarrhea-predominant irritable bowel syndrome in human subjects. PLoS One, 10(5), e0126438.
  5. Dukowicz, A. C., Lacy, B. E., & Levine, G. M. (2007). Small intestinal bacterial overgrowth: a comprehensive review.Gastroenterology & hepatology, 3(2), 112.
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