Bloating, frequent belching, a feeling of fullness, abdominal pain, or persistent constipation can have a substantial impact on daily life. When routine tests do not explain these symptoms, some people wonder whether small intestinal bacterial overgrowth could be a contributing factor.
SIBO stands for small intestinal bacterial overgrowth. It describes an altered amount or composition of microorganisms in the small intestine. This page explains how SIBO may be assessed, which other causes should be considered, and why treatment needs to be individualised.
The small intestine normally contains far fewer microorganisms than the large intestine. If carbohydrate fermentation increases there, gas can develop and cause distension, pressure, fullness, or pain. Breath tests commonly measure hydrogen and methane. Increased methane is now often described as intestinal methanogen overgrowth (IMO) and may be associated with slower bowel transit and constipation.
These symptoms are not specific to SIBO. They can also occur with food intolerances, irritable bowel syndrome, coeliac disease, altered gut motility, medication effects, or other digestive conditions. Symptoms alone therefore cannot confirm a diagnosis.
During a breath test, a lactulose solution is taken and breath samples are analysed at defined intervals. The result should be interpreted alongside the timing of gas production, symptoms, and the clinical context. Breath testing has limitations; no single result replaces a medical assessment.
The goal is not simply to reduce bloating for a short time. Depending on the findings, bowel motility, previous abdominal surgery, anatomical factors, associated conditions, nutrition, and medication may need review. Highly restrictive diets should not be continued without a clear indication and professional guidance.
Antibiotics and other measures are considered case by case. Choice, duration, and follow-up depend on the diagnosis and individual risks; self-treatment and promises of a permanent cure are not appropriate. If symptoms persist or recur, the diagnosis and possible underlying causes should be reviewed.
At Dr. Anna Mueller's practice in Munich, we review symptoms, available reports, and medication. Where indicated, assessment may include a breath test and a realistic follow-up plan. Warning signs such as unintentional weight loss, bleeding, anaemia, fever, or severe pain require prompt medical assessment.