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October 30, 2025
Sharon Burbat
If the stomach constantly rebels… Bloating, stomach pain, and digestive issues right after eating? These symptoms could be caused by bacterial overgrowth in the small intestine, also known as SIBO.
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Many people know the unpleasant feeling when digestion just doesn't want to cooperate. It is often referred to as irritable bowel syndrome or blamed on “too much stress. But what if something completely different is behind the complaints? A possible - and often overlooked - cause is SIBO. What is behind the abbreviation, why it affects so many, and how to finally get the complaints under control.
SIBO stands for Small Intestinal Bacterial Overgrowth, a bacterial overgrowth of the small intestine. Normally, there are few bacteria in the small intestine - compared to the colon, which has a high microbial density. However, in SIBO, intestinal bacteria multiply excessively in the small intestine, where they do not belong.
The result: The bacteria begin to ferment undigested carbohydrates there. This produces gases like hydrogen or methane, which can lead to bloating, abdominal pain, diarrhea, or constipation.
SIBO can manifest in many different ways, often with diffuse symptoms. This often makes the diagnosis so difficult. However, the most common symptoms include:
Since many of these symptoms also occur in irritable bowel syndrome (IBS), SIBO is often overlooked and patients are sometimes misdiagnosed for years.
SIBO is not an independent disease but usually the result of other disorders in the gastrointestinal tract or metabolism. Common causes and risk factors include:
Diagnosing SIBO is not always straightforward. The most common method is a breath test with lactulose or glucose. This measures how much hydrogen or methane is exhaled after ingesting a sugar solution, which indicates bacterial fermentation in the small intestine.
However, breath tests are not standardized and can give false-positive and false-negative results. A holistic consideration of symptoms, medical history, and findings is therefore essential. In addition, blood tests for nutrient deficiencies, stool analyses to identify dysbiosis or inflammation, and imaging (if anatomical causes are suspected) may be used.
The treatment of SIBO is multi-stage and individually tailored. The goal is to reduce bacterial overgrowth, stabilize the intestinal barrier, and address the causes.
Medications or herbal preparations to promote small intestine movement to prevent relapse (examples: prucalopride, low-dose erythromycin, Iberogast®)
Treating symptoms alone is not enough. It is important in the long term to find and address the cause of the dysbiosis: for example, to improve bowel movement, reduce stress, or restore balance in the microbiome.
Unfortunately, SIBO has a high relapse rate, especially if the underlying triggers persist. Studies show that up to 50% of those affected may develop symptoms again after 6–9 months. Therefore, sustainable follow-up care is crucial, including regular breath tests in chronic cases, nutritional counseling by qualified professionals, and long-term gut care (stress management, exercise, gut microbiome strengthen).
In recent years, evidence has been mounting that a significant portion of IBS diagnoses actually stem from SIBO. Studies show that up to 60–80% of IBS patients test positive in breath tests. Rifaximin has also been shown in studies to significantly alleviate symptoms in IBS-D (diarrhea-predominant). A targeted SIBO screening for IBS symptoms could therefore help many patients achieve more effective treatment.
SIBO is a typical example of a hidden cause that can go undetected for years, even though the symptoms are severe. Anyone suffering from unclear digestive problems should therefore also consider SIBO, especially if classic irritable bowel therapies do not help.
The right diagnosis, targeted treatment, and conscious management of diet and lifestyle can make the difference and improve quality of life again.
