Quick answer: Small intestinal bacterial overgrowth (SIBO) is a condition in which too many bacteria build up in the small intestine, where there are normally relatively few. This can interfere with digestion and cause bloating, wind and other tummy symptoms. It is a genuine, recognised condition, but it is also over-diagnosed in wellness circles, so proper assessment by a doctor matters. Because its symptoms overlap heavily with irritable bowel syndrome (IBS), SIBO should not be self-diagnosed. In Singapore, start with your GP, who can refer you to a gastroenterologist or dietitian if needed. Unexplained weight loss, blood in the stool, or a persistent change in bowel habit always need prompt medical assessment.
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If you have ongoing bloating, wind and an unsettled tummy, you may have come across the term SIBO online. It is a real condition worth understanding, but the internet also carries a lot of hype around it. This guide explains what SIBO is, how doctors assess it, and how it is treated, with a measured, evidence-based view.
What SIBO is
The small intestine sits between the stomach and the large bowel and does most of the work of digesting food and absorbing nutrients. It normally contains relatively few bacteria compared with the large intestine. In SIBO, bacteria that belong further down the gut become too numerous in the small intestine. As these bacteria ferment food, they can produce gas and interfere with normal digestion, leading to tummy symptoms.
It is worth being clear-eyed here. SIBO is a recognised medical condition, but it has also become a popular label in wellness circles, where it is sometimes blamed for a wide range of vague symptoms without proper evidence. Because of this over-diagnosis, careful assessment is important rather than assuming SIBO is the cause of every digestive complaint.
Symptoms
The common symptoms of SIBO include:
- Bloating and a feeling of abdominal distension
- Excess wind (flatulence)
- Tummy pain or discomfort
- Diarrhoea, or in some people constipation
In more significant cases, the overgrowth can interfere with the absorption of nutrients. This may lead to unintended weight loss or to deficiencies of certain vitamins and minerals over time. These features overlap with many other digestive conditions, which is one reason a proper assessment matters.
Causes and who is at risk
SIBO tends to develop when something disrupts the normal balance that keeps bacteria in check. This can include anything that slows the movement of the gut, alters its structure, or weakens its natural defences. Contributing factors can include:
- Previous surgery on the gut, which can change its anatomy
- Conditions that affect how the gut moves, such as diabetes-related nerve changes or scleroderma
- Structural issues within the small intestine
- Low stomach acid, which normally helps limit bacterial numbers
Because of this, SIBO often occurs alongside another underlying problem rather than on its own. Identifying and addressing that underlying cause is a key part of managing it well.
Overlap with IBS
SIBO and irritable bowel syndrome share many of the same symptoms, including bloating, wind, tummy discomfort and altered bowel habit. The relationship between the two is debated among specialists, and it is not always clear where one ends and the other begins. This overlap is precisely why SIBO should not be self-diagnosed. Symptoms alone cannot reliably tell these conditions apart, so a doctor’s assessment is needed to work out what is actually going on.
How it is diagnosed
Diagnosis begins with a doctor’s assessment of your symptoms, medical history and any risk factors. Tests may be used to support this, most commonly a breath test, which looks for gases produced when bacteria ferment a test substance. It is important to know that these tests have limitations and are not perfectly accurate, so results are interpreted alongside the wider clinical picture rather than in isolation.
Equally important is looking for an underlying cause. Because SIBO often sits on top of another condition, your doctor may investigate what has allowed the overgrowth to develop, as treating that cause helps reduce the chance of it returning.
Treatment
Treatment is usually built around several strands, tailored to the individual:
- Treating any underlying cause. Where a condition or structural issue is driving the overgrowth, addressing it is central to lasting improvement.
- A course of antibiotics. A doctor may prescribe a course of antibiotics to reduce the bacterial overgrowth. This should always be doctor-directed rather than self-managed.
- Dietary approaches. Some people benefit from working with a dietitian on their eating pattern. This is best done with professional guidance rather than following restrictive diets found online.
- Addressing nutrition. If poor absorption has led to deficiencies, correcting these is part of care.
Symptoms can recur after treatment, particularly if an underlying cause remains. This is why managing that root issue, alongside treating the overgrowth itself, matters for the longer term.
A note of caution
SIBO has become a marketing hook online, with an industry of unproven “SIBO cures”, heavily restrictive diets, cleanses and supplements. Many of these lack good evidence, can be expensive, and restrictive eating in particular can do harm, including nutritional shortfalls and an unhealthy relationship with food. Rather than self-treating based on online claims, see a doctor and, where appropriate, a dietitian who can guide you safely.
When to see a doctor
See a GP if you have persistent tummy symptoms such as ongoing bloating, wind, pain or a change in your bowel habit that does not settle. You should seek prompt assessment for any red flag symptoms, including unexplained weight loss, blood in the stool, or a persistent change in bowel habit. These features are not specific to SIBO and can point to other conditions that need to be checked. Your GP can arrange the right tests and refer you to a gastroenterologist or dietitian if needed.
Common questions
Is SIBO the same as IBS?
No. They are separate labels, though their symptoms overlap heavily and the relationship between them is debated. This is one reason a proper assessment is needed rather than self-diagnosis.
Can I diagnose SIBO myself from my symptoms?
No. The symptoms are shared with several other digestive conditions, so they cannot reliably point to SIBO on their own. A doctor’s assessment, sometimes with a breath test, is needed.
Are the breath tests reliable?
Breath tests can support a diagnosis but they have limitations and are not perfectly accurate. Results are interpreted alongside your history and examination, not on their own.
Will antibiotics cure it for good?
A course of antibiotics can reduce the overgrowth, but symptoms may recur, especially if an underlying cause remains. Managing that cause is important for lasting improvement.
Do I need a special SIBO diet?
Some people benefit from dietary changes, but these are best made with a dietitian. Restrictive diets and supplements marketed online can do more harm than good.
Related guides
Sources
- Singapore General Hospital
- HealthHub
- American College of Gastroenterology
- NHS
Disclaimer: This guide is for general information only and is not a substitute for personalised medical advice. It should not be used to diagnose or treat any condition. Unexplained weight loss, blood in the stool, or persistent tummy symptoms need to be assessed by a doctor. If you are unwell or concerned, please see your GP or a gastroenterologist in Singapore.