What is SIBO?
SIBO affects 1 in 9 adults, yet most have never heard of it.
What is SIBO?
Small Intestinal Bacterial Overgrowth
SIBO (pronounced “see-bo”) is a gastrointestinal (GI) disorder that occurs when there is an overabundance of bacteria in your small intestine. While it’s normal to have bacteria in your small intestine, if it is the wrong kind or too many, it can disrupt the balance of your gut microbiome and wreak havoc on your digestive system. These “disruptor” bacteria cause various health problems including painful bloating, diarrhea, constipation, brain fog, and fatigue.
SIBO is not a primary disease but rather a condition resulting from an underlying root issue that is causing the dysmotility. Common causes of SIBO include:
Other GI diseases, including IBS, IBD, Celiac disease, and others
Prescription medications such as antibiotics or opioids
Food poisoning
Despite its prevalence, SIBO is frequently overlooked, misdiagnosed, or dismissed. Many people with SIBO struggle for years with symptoms before receiving an accurate diagnosis.
Symptoms of SIBO
SIBO results in many debilitating symptoms in the digestive system and beyond:
Digestive Symptoms:
Abdominal bloating and distension
Abdominal discomfort and/or cramps
Excessive gas leading to belching and/or flatulence
Heartburn and/or acid reflux
Nausea
Nutritional deficiencies, including iron and B12
Non-Digestive Symptoms:
Fatigue
Brain Fog
Headaches
Weight loss/gain
Joint pain
Mood symptoms
Skin problems, such as eczema and rashes
SIBO & IMO
Types of SIBO
It can be useful to categorize SIBO by the major gases the overgrowth produces. There are three types: hydrogen dominant (SIBO), methane dominant (IMO) and hydrogen sulfide dominant. Because the gases are produced by different strains of bacteria or archaea that are over colonizing the small intestine, this is the clearest indicator of your type.
Antibiotic therapy can be tailored to target the specific type of overgrowth if known. Additionally, there are different symptom profiles associated with each type:
Hydrogen Dominant SIBO typically causes diarrhea in patients and overlaps with the symptoms of IBS-D.
Methane Dominant SIBO has been reclassified as Intestinal Methanogen Overgrowth (IMO), as the methane producing microorganisms are archaea not bacteria. These methanogens are naturally present in the gut, but can overgrow in both the small intestine and the large intestine. IMO typically causes constipation and overlaps with the symptoms of IBS-C.
Hydrogen Sulfide Dominant SIBO typically causes diarrhea in patients, similar to hydrogen dominant SIBO. Certain breath tests measure hydrogen sulfide levels alongside hydrogen and methane and can help differentiate between the types when symptoms overlap.
SIBO Awareness
April 8th is SIBO Awareness Day
This April, join the movement to raise awareness for SIBO—an often-overlooked condition affecting millions. Our mission is to educate, support, and provide resources so those suffering can find the right treatment, take control of their gut health, and reclaim their lives.
75%
78%
in US have never heard of SIBO
of IBS patients have SIBO
27%
44%
in US feel dismissed by doctors when discussing GI symptoms
in US suffer from digestive discomfort
SIBO Diagnosis
Official diagnosis of of SIBO can help guide effective treatment and improve digestive health. Consult with your doctor to determine the best method for you.
Which Test Is Right For You?
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Breath Test
Most widely available and least invasive. Options now include at-home testing kits as well as in-clinic testing.
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Bowl Aspiration
More costly and invasive procedure that provides a more in-depth view of the bacteria.
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Symptomatic Diagnosis
Doctors can review your symptoms and make a diagnosis based on your clinical presentation.
#KnowSIBO
Know SIBO: Frequently Asked Questions
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An overgrowth of bacteria in the small intestine. These ‘disruptor’ bacteria create excessive gas and lead to a multitude of uncomfortable symptoms.
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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.
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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.
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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.
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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.
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ItemSIBO 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
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No, SIBO is not contagious, however some of the underlying conditions, for example norovirus food poisoning, may be considered contagious.
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Estimates vary but one retrospective study found that 33.8% of patients that underwent breath testing after reporting gastrointestinal distress had SIBO.