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October 30, 2025
Sharon Burbat
If the stomach constantly rebels... Bloating, abdominal pain, and digestive issues right after eating? These symptoms could be due to bacterial overgrowth in the small intestine, also known as SIBO.
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Many are familiar with the uncomfortable feeling when digestion simply doesn't cooperate. It is often referred to as irritable bowel syndrome or attributed to "too much stress." But what if something entirely different is behind the symptoms? One possible—and often overlooked—cause is called SIBO. What lies behind the abbreviation, why it affects so many, and how to finally get the symptoms under control.
SIBO stands for Small Intestinal Bacterial Overgrowth, which means a bacterial overgrowth of the small intestine. Normally, only a few bacteria live in the small intestine—in contrast to the large intestine, which has a high microbial density. However, in SIBO, gut 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 such as hydrogen or methane, which can lead to bloating, abdominal pain, diarrhea, or constipation.
SIBO can manifest very differently, the symptoms are often diffuse. This often makes the diagnosis so difficult. However, the most common symptoms include:
Since many of these symptoms also occur with irritable bowel syndrome (IBS), SIBO is often overlooked and sufferers 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 using lactulose or glucose, measuring 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 yield false-positive and false-negative results. A holistic view of symptoms, medical history, and findings is therefore essential. Additionally, 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 underlying causes.
Medications or herbal preparations to promote small intestine movement to prevent relapses (examples: prucalopride, low-dose erythromycin, Iberogast®).
Treating only symptoms is not enough. In the long term, it is important to find and address the cause of the dysbiosis: for example, improving bowel movement, reducing stress, or restoring 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, strengthening the gut microbiome).
In recent years, evidence has been mounting that a significant portion of IBS diagnoses are actually due to SIBO. Studies show that up to 60-80% of IBS patients show positive breath tests. Rifaximin has also been shown in studies to significantly relieve symptoms in IBS-D (diarrhea-predominant). Therefore, targeted SIBO screening in irritable bowel symptoms could 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. Those suffering from unclear digestive problems should therefore also consider SIBO, especially when classic IBS therapies do not help.
The right diagnosis, targeted treatment, and a conscious approach to nutrition and lifestyle can make a difference and improve quality of life again.
