Getting the Right Diagnosis for Digestive Symptoms: Is It Really IBS or SIBO?

Digestive issues can be incredibly frustrating to live with—whether it’s bloating, abdominal pain, gas, irregular bowel movements, or a general sense of discomfort. Often, these symptoms are lumped together under the diagnosis of Irritable Bowel Syndrome (IBS), but is that really the whole story?

IBS is considered a diagnosis of exclusion, meaning it’s typically given when no other clear cause for symptoms can be found. However, not every diagnosis of IBS is accurate—many people are misdiagnosed when, in fact, their symptoms could be caused by Small Intestinal Bacterial Overgrowth (SIBO) or another underlying issue. Let’s explore how to get the right diagnosis and why it matters.

Why Getting the Right Diagnosis Matters

Living with chronic digestive issues without a clear diagnosis is not just uncomfortable—it can also impact your overall health and quality of life. Symptoms like bloating, gas, and abdominal pain can persist for years if the root cause isn’t addressed. That’s why getting the correct diagnosis is essential for effective treatment and long-term relief.

Too often, people are given an IBS label without proper investigation. IBS should not be a catch-all diagnosis—especially when other treatable conditions like SIBO or gut infections could be the real issue.

Step 1: Start with Your GP

Your General Practitioner (GP) is your first point of contact for investigating digestive symptoms. A thorough initial evaluation should include:

• Screening for Coeliac Disease: A simple blood test can detect markers for coeliac disease. It’s crucial to rule this out early, as untreated coeliac disease can cause long-term gut damage.

• Testing for Parasites: If your symptoms began after travel or an acute illness, a stool test to check for parasitic infections is important.

• Referral to a Specialist: If your symptoms are severe or persistent, ask for a referral to a gastroenterologist who can conduct more comprehensive testing.

Step 2: Understand IBS as a Diagnosis of Exclusion

IBS is a functional gut disorder characterised by symptoms like abdominal pain, bloating, and changes in bowel habits. However, it should only be diagnosed after excluding other potential causes. If your GP has labeled your symptoms as IBS without conducting thorough tests, advocate for a more comprehensive investigation.

IBS should never be given as a default diagnosis without first ruling out conditions like coeliac disease, inflammatory bowel disease (IBD), parasitic infections, or SIBO. If your symptoms don’t resolve with standard IBS treatments, it’s worth considering other potential causes. If you require constant medications or a restrictive diet to manage your symptoms then I would encourage you to keep investigating to find the root cause of your symptoms.

Step 3: Could Your IBS Actually Be SIBO?

One of the most overlooked causes of IBS-like symptoms is Small Intestinal Bacterial Overgrowth (SIBO). In fact, up to 80% of IBS cases might actually be SIBO.

SIBO occurs when bacteria that are normally found in the large intestine migrate to the small intestine, where they ferment carbohydrates, producing gases like hydrogen and methane. This leads to symptoms such as:

• Bloating and gas

• Abdominal pain

• Diarrhoea or constipation (or a mix of both)

• Nausea

• Fatigue

The most accurate way to diagnose SIBO is with a breath test, where you drink a series of sugar solutions (like lactulose or glucose) and then measure hydrogen and methane levels in your breath over a few hours. This test can be done at home. Elevated levels indicate bacterial overgrowth.

Step 4: Functional Testing for Digestive Health

If conventional testing doesn’t provide answers, consider functional testing to dig deeper. These tests can help identify specific imbalances or issues that might be overlooked in standard medical evaluations.

• Breath Testing for SIBO: Detects bacterial overgrowth by measuring hydrogen and methane levels.

• Leaky Gut (Intestinal Permeability) Testing: Identifies compromised gut lining that can lead to systemic inflammation and immune activation.

• Microbiome Sequencing: Provides a detailed analysis of gut bacteria diversity and composition, helping identify dysbiosis or imbalances that could be driving symptoms.

These tests are particularly useful if your GP has ruled out common conditions but you still experience symptoms. Functional testing can give you a clearer picture of what’s happening in your gut and guide targeted treatment.

Step 5: Personalised Treatment Matters

Getting the right diagnosis is just the first step. Treatment for digestive issues must be personalised, considering factors like:

• Dietary adjustments (low FODMAP, SIBO-specific diet)

• Antimicrobial protocols (ideally herbal, to avoid microbiome damage)

• Gut motility support

• Addressing underlying imbalances

If your GP is unable to support your ongoing care or you haven't experienced the relief you're looking for, as a gut health specialist I can help you develop a tailored plan.

Don’t Settle for Incomplete Answers

Living with digestive discomfort is not something you should have to accept. A clear and accurate diagnosis can transform your approach to managing symptoms and improving your quality of life. A low FODMAP diet can be helpful to manage symptoms but this should only be used short term (6-8 weeks) to avoid nutrient deficiency. Your care provider should have a clear plan to transition you away from a restrictive diet in a way that supports the natural function of your digestive system. If you feel your symptoms are being dismissed or inadequately investigated, keep asking questions and seeking the support you deserve.

If you’re feeling overwhelmed by conflicting information or stuck with a vague diagnosis, I’m here to help. Book a 1:1 consultation to discuss your symptoms, explore potential causes, and develop a clear path forward.

Getting the right diagnosis is the first step to lasting relief—let’s find the answers together.