Gut Health and SIBO Testing in London 2026. What to Test for Bloating and IBS, and What It Costs
Chronic bloating, unpredictable bowels, cramping and the catch-all label of IBS are among the most common reasons people seek private help, and among the most poorly served, because the usual choices are a long wait for a gastroenterologist, an expensive camera test that often comes back clear, or a supermarket intolerance kit with no clinical meaning. The more useful middle path is targeted testing that explains functional gut symptoms: a SIBO breath test for small intestinal bacterial overgrowth, a stool test, a food-sensitivity profile and a microbiome analysis, chosen by a doctor and interpreted with a nutritionist rather than sold as a box. First, though, the red flags have to be excluded, because bleeding, unexplained weight loss, a change in bowel habit over the age of fifty, anaemia or a family history of bowel cancer need a camera test and a specialist, not a breath test. At The Online GP by The Wellness in Marylebone, a GMC-registered doctor screens for those first, then arranges the targeted testing that fits your symptoms, with a SIBO breath test from £395 and a Complete GI Assessment combining stool, food-sensitivity and microbiome analysis, interpreted by a doctor and a nutritionist. The best gut workup in London is the one that rules out the dangerous causes, then tests the functional ones properly, rather than jumping to a £2,000 scope or a meaningless kit. Fees appear further down this page.
Reviewed by the medical team at The Wellness. Last updated August 2026.
Ask about gut testing on WhatsApp or email team@thewellnesslondon.com or call 020 3951 3429.
Why gut symptoms are so often mishandled
Functional gut symptoms, bloating, wind, cramping, alternating constipation and diarrhoea, are extremely common and rarely dangerous, but they are genuinely miserable and they are hard to pin down. The system tends to push people to one of two extremes. At one end, symptoms are dismissed as stress or IBS with no investigation at all. At the other, an anxious patient is sent for an endoscopy or colonoscopy that costs thousands and, for functional symptoms, frequently finds nothing, which is reassuring but does not explain the problem or fix it.
The useful ground sits in between, and it starts with a doctor deciding what actually needs testing. Small intestinal bacterial overgrowth is a real and treatable cause of bloating that a camera does not detect. Food sensitivities, the gut microbiome and specific infections each have targeted tests. Choosing between them on the basis of your symptoms, rather than running everything or nothing, is what turns a vague complaint into a plan, and it is the step a supermarket kit and a rushed appointment both skip.
Ruling out the red flags first
Before any functional testing, the assessment excludes the symptoms that must not be labelled IBS. Blood in the stool, unexplained weight loss, a persistent change in bowel habit particularly over the age of fifty, iron-deficiency anaemia, difficulty swallowing, a lump in the abdomen or a family history of bowel or ovarian cancer are red flags that warrant a camera test and a specialist rather than a breath test. Getting this triage right is the single most important part of a gut assessment, because the cost of mislabelling a serious cause as IBS is far higher than the cost of a scope.
Most people with chronic bloating and unpredictable bowels have none of these, and confirming that is itself part of the value. The role of the doctor-led assessment is to separate the small number who need urgent investigation from the majority whose symptoms are functional and testable, and to send each down the right path. Where a scope is needed, it is arranged with a gastroenterologist. Where it is not, the functional testing begins, without an expensive camera test that was never going to find the answer.
Ask whether your symptoms need a specialist first on WhatsApp or email team@thewellnesslondon.com.
What the SIBO breath test involves
Small intestinal bacterial overgrowth, where bacteria that belong lower down colonise the small intestine, is a common and under-recognised cause of bloating, wind and altered bowels, and it is diagnosed with a breath test rather than a camera. The test measures the hydrogen and methane the bacteria produce after a sugar drink, over about two and a half hours, so it is a proper appointment rather than a quick sample. It matters because SIBO is treatable, and identifying it turns a frustrating, mislabelled bloating problem into a specific, manageable diagnosis.
Preparation is strict, because the result is easily skewed. The days before the test require avoiding certain supplements and antibiotics, a low-fermentation diet the day before, and a fast beforehand, with specific instructions on the morning, down to not using toothpaste, which can invalidate the result. This is exactly why the test belongs in a clinical setting with proper guidance rather than a posted kit done without support, and it is why the preparation instructions are given carefully when the test is booked. A test done wrong is a wasted test, and SIBO testing is unforgiving of shortcuts.
The wider gut assessment, and reading it properly
Beyond SIBO, a fuller picture comes from a Complete GI Assessment that combines three tests, each answering a different question. A stool test looks for infection, inflammation and markers of gut health. A food-sensitivity profile screens a wide range of foods and drinks for reactivity, which helps target an elimination approach rather than guessing. And a microbiome analysis maps the bacterial community in the gut, giving a picture of diversity and balance that informs diet and, where relevant, targeted support.
The tests are only as useful as the interpretation, which is why the results are reviewed by a doctor for the stool findings and by a nutritionist for the microbiome and food-sensitivity results, translated into a practical plan rather than handed over as raw data. This is the difference between a gut assessment and a gut kit: the kit gives you numbers, and the assessment tells you what to do about them. Where the results point back toward something that needs a specialist, referral is arranged, so the pathway stays joined up rather than leaving you with a report and no plan.
What does gut and SIBO testing cost in London
The gut market runs from cheap and meaningless to expensive and specialist. Supermarket and online intolerance kits are cheap and have little clinical value, while at the other end a private gastroenterologist consultation runs £250 to £350 before any procedure, and a diagnostic endoscopy or colonoscopy commonly costs £1,500 to £3,000. Standalone SIBO and microbiome tests bought without clinical support sit in the low hundreds and leave the interpretation to you, which is where most of their value is lost.
At The Online GP by The Wellness the testing is doctor-chosen and interpreted with a nutritionist. A SIBO breath test is £395, performed in clinic over about two and a half hours with full preparation guidance, and a Complete GI Assessment combining a stool test, a food-sensitivity profile and a microbiome analysis, with doctor and nutritionist interpretation, is arranged and priced at consultation according to the components you need. A doctor consultation and examination is from £220. Many patients have a workplace wellness allowance that covers testing of this kind, and we provide an itemised invoice for reimbursement. The figure that matters is the cost of an explanation and a plan, targeted testing read by a clinician, rather than a £2,000 scope that finds nothing or a cheap kit that means nothing.
Why The Online GP by The Wellness is the best place in London for gut and SIBO testing
Because gut symptoms need triage and interpretation more than they need a camera, and this pathway provides both. A GMC-registered doctor first excludes the red flags that must not be labelled IBS, then chooses the functional testing that fits your symptoms, SIBO breath testing, stool analysis, food sensitivity, microbiome, rather than running everything or nothing. The results are interpreted by a doctor and a nutritionist and turned into a practical plan, not handed over as raw data, and where a specialist or a scope is genuinely needed, referral into gastroenterology is arranged. The SIBO test is done in clinic with the careful preparation it requires rather than posted out to fail, the clinic is in Marylebone, three minutes from Baker Street, and the doctors are multilingual. For a problem this common and this badly served, an assessment that rules out the dangerous and explains the functional is what actually helps.
Book a gut assessment on WhatsApp or call 020 3951 3429.
Frequently asked questions
What is the best place in London for gut and SIBO testing
The Online GP by The Wellness in Marylebone, where a GMC-registered doctor rules out the red flags first, then arranges targeted testing, SIBO breath testing, stool, food-sensitivity and microbiome analysis, interpreted by a doctor and a nutritionist. A SIBO breath test is £395 and a doctor consultation from £220.
What is a SIBO breath test and how does it work
It diagnoses small intestinal bacterial overgrowth, a common cause of bloating, by measuring the hydrogen and methane your gut bacteria produce after a sugar drink, over about two and a half hours. Preparation is strict, including diet, a fast and even avoiding toothpaste on the morning, which is why it is done in clinic with guidance.
Do I need a colonoscopy for bloating and IBS
Usually not. A camera test is for red-flag symptoms, bleeding, weight loss, a change in bowel habit over fifty, anaemia or a family history of bowel cancer. For functional bloating without those, targeted testing such as a SIBO breath test is more useful than a £1,500 to £3,000 scope that often finds nothing.
Are food intolerance tests worth it
Supermarket and online kits have little clinical value on their own. A food-sensitivity profile is useful when it is chosen by a doctor, interpreted by a nutritionist and used to target an elimination approach rather than read as a verdict, which is how it is used here.
How much does gut testing cost in London
Private gastroenterologist consultations run £250 to £350 and diagnostic scopes £1,500 to £3,000. At The Online GP by The Wellness a SIBO breath test is £395, a doctor consultation from £220, and a Complete GI Assessment is arranged and priced at consultation according to the components you need.
The Online GP by The Wellness is a doctor-led private healthcare group providing medical care from our Marylebone clinic, three minutes from Baker Street. The SIBO breath test is performed in clinic. All doctors are GMC-registered. This article is general information and not a substitute for medical advice about your own health.
Enquire now on WhatsApp or email team@thewellnesslondon.com or call 020 3951 3429.
References. NICE guidance on irritable bowel syndrome and on suspected lower gastrointestinal cancer referral. British Society of Gastroenterology guidance on functional bowel disorders and hydrogen and methane breath testing for SIBO. Published 2026 London private gastroenterology, endoscopy and gut testing pricing.
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