A patient’s story
Anna, a 34-year-old London professional, had been struggling with bloating, abdominal discomfort, and irregular bowel habits for months. Her GP suggested she might have SIBO, a small intestinal bacterial overgrowth, and recommended a breath test. Sophie was relieved to finally have a test but felt anxious when she read online that the results might not always be accurate.
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If you have similar symptoms, it is important to understand what a SIBO breath test can and cannot tell you.
What is a SIBO Breath Test?
A SIBO breath test measures gases such as hydrogen and methane in your breath after consuming a specific sugar solution. The test detects bacterial fermentation in your small intestine, which can explain bloating, abdominal pain, and changes in bowel habits.
It is simple, non-invasive, and can be done at home, but accuracy varies.
Why Breath Test Results Can Be Misleading
Even though breath testing is widely used, several factors can affect the results:
Location of Overgrowth: SIBO can occur anywhere in the small intestine. The test mainly captures the upper part, so bacteria lower down may be missed
False Positives: Certain foods, medications, or natural variations in gut bacteria can raise gas levels, mimicking SIBO
Test Sensitivity: Different labs and test types vary in reliability. Not all tests detect both hydrogen and methane
Breath Sampling Issues: Inaccurate collection or contamination can skew results. Following instructions closely is essential
Intermittent Overgrowth: Bacterial patterns can fluctuate. A single test may miss SIBO if symptoms are not active that day
Dietary Preparation: Pre-test diet can temporarily reduce bacterial activity, lowering gas production and affecting results
Rapid Intestinal Transit: Food moving too quickly through the small bowel may prevent gas buildup, leading to false negatives
Subtypes of SIBO: Some patients have methane-predominant SIBO, which certain tests may not detect
Antibiotic Use: Recent antibiotics can temporarily suppress bacteria, altering test results
How We Diagnose SIBO at LSDC
At LSDC Healthcare, we never rely on a breath test alone. Our approach combines:
Detailed review of your symptoms and medical history
Properly conducted breath testing
Follow-up consultations to interpret results in context
If SIBO is strongly suspected despite a negative test, we may recommend:
Repeat breath testing
Endoscopic evaluation
Additional investigations to rule out other digestive conditions
This ensures a reliable, personalised diagnosis so treatment can be accurately tailored.
When to Seek Specialist Review
Persistent bloating, gas, or abdominal discomfort
Changes in bowel habits that affect daily life
Negative test results but ongoing symptoms
Previous misdiagnoses or ineffective treatments
Speak to a clinician about your symptoms
If bloating, gas, or abdominal discomfort is affecting your life, LSDC Healthcare offers expert assessment, breath testing, and personalised guidance to identify and manage SIBO effectively.