Why Most IBS Cases Are Actually Undiagnosed SIBO: What Your Doctor Isn’t Telling You

If you’ve ever walked into a doctor’s office complaining of bloating, constipation, cramping, and other digestive woes, only to walk out with the diagnosis of Irritable Bowel Syndrome (IBS), you’re not alone.

It’s a frustrating experience, to say the least. You go in hoping for answers, a clear explanation for why your gut feels like it’s constantly at war with itself, and instead, you leave with a label that says your bowel is simply “irritable.” But what does that even mean? Why is your bowel irritable? Unfortunately, in many cases, IBS isn’t really a diagnosis—it's a symptom of something deeper going on, often undiagnosed Small Intestinal Bacterial Overgrowth (SIBO).

IBS: A Symptom, Not a Diagnosis

Let’s get one thing straight: IBS is not a diagnosis. It’s a catch-all term that essentially means, “We know something’s wrong, but we’re not sure what.” It’s a description of symptoms rather than an identification of the root cause. When you hear “IBS,” it’s easy to think you’ve got a clear-cut diagnosis, but in reality, it’s a way of saying your gut is unhappy without understanding why.

The truth is, many doctors simply don’t have the time to dig deeper. They rule out the extremes—like colon cancer, inflammatory bowel disease, or the need for immediate surgery—and if those aren’t the issue, you’re often sent on your way with advice to “eat more fiber” or take Pepcid. This approach might manage your symptoms temporarily, but it doesn’t get to the root of the problem and actually can make things worse long term. Andddd that’s where many people with IBS are left in limbo, continuing to suffer without real answers.

The Real Culprit: Undiagnosed SIBO

Here’s what many people don’t realize: a significant number of IBS cases are actually caused by SIBO—Small Intestinal Bacterial Overgrowth. SIBO occurs when bacteria that normally reside in the large intestine migrate to the small intestine, where they don’t belong. These bacteria can ferment the food you eat, leading to gas production, bloating, abdominal pain, constipation, diarrhea, and all the other lovely symptoms you’ve been experiencing. Sound familiar?

Studies suggest that up to 60-80% of people diagnosed with IBS actually have SIBO. So why aren’t more people being tested for SIBO? Unfortunately, the standard practice in many medical settings is to treat the symptoms rather than explore the underlying cause. This approach leaves countless people suffering needlessly when a proper diagnosis could lead to more effective treatment.

The Three Types of SIBO: To Make Things Even More Confusing...

SIBO isn’t a one-size-fits-all condition; it comes in different forms, each with its own set of challenges:

1. Hydrogen-Dominant SIBO: This type is often associated with diarrhea (IBS-D) and results from an overgrowth of bacteria that produce hydrogen gas. The excess hydrogen can irritate the gut lining and speed up transit time, leading to loose stools and cramping.

2. Methane-Dominant SIBO: Methane-producing archaea (a type of microorganism) are responsible for this form of SIBO, which is often linked to constipation (IBS-C). Methane gas slows down gut motility, causing bloating, constipation, and abdominal discomfort.

3. Hydrogen Sulfide SIBO: This type is less common and can present with a mix of diarrhea and constipation, along with the telltale sign of foul-smelling gas. Hydrogen sulfide gas can be highly irritating to the gut lining, contributing to inflammation and a wide range of gut symptoms. Body wide inflammatory or "toxic" symptoms are often seen here as well; headaches, chronic fatigue, etc.

   
   

Identifying which type of SIBO you have is crucial because it dictates the treatment approach. But getting to that point requires specific testing—something that’s often overlooked in a quick doctor’s visit.

Testing, Retesting, and the Journey to Recovery

Treating SIBO isn’t a one-and-done process. It’s an entire journey that requires patience, persistence, and a willingness to dig deep. The first step is accurate testing, usually through a breath test that measures the levels of hydrogen and methane gases produced after consuming a specific sugar solution. This test helps determine not only the presence of SIBO but also the type you have.

Once diagnosed, treatment typically involves a combination of antibiotics or herbal antimicrobials to reduce bacterial overgrowth, along with dietary modifications to starve the unwanted bacteria. But the journey doesn’t stop there. After initial treatment, retesting is often necessary to ensure the SIBO has been adequately addressed (unfortunately this step is missed most of the time). SIBO has a high recurrence rate, which is why prevention strategies—like maintaining a healthy diet, supporting gut motility, and addressing underlying causes such as low stomach acid or motility issues—are key to long-term success.

Why a Gut Health Dietitian Is Your Best Ally

If you’ve been stuck in the cycle of receiving an IBS diagnosis without getting real answers, it’s time to take a different approach. As a gut health dietitian, my focus is on finding the root cause of your symptoms, not just treating them on the surface. I work closely with my clients to explore the underlying issues contributing to their gut health problems, using tools like SIBO testing, personalized nutrition plans, and lifestyle modifications to restore balance to the gut.

I understand the frustration of feeling like you’re not being heard or that your symptoms are being dismissed. That’s why I’m dedicated to helping you get to the bottom of what’s really going on in your gut. By identifying and treating conditions like SIBO, we can finally put an end to the cycle of bloating, constipation, cramping, and discomfort—and help you reclaim your life.

SIBO often causes a lot of body wide symptoms as well such as chronic fatigue, histamine intolerance, acne, brain fog, weight gain - yeppp that "I've gained 10 lbs this year and have no clue why?" situation?! This happens because those bacteria when they die off release things called lipopolysaccharides (aka toxins) that then leach out into your blood stream and effect your entire body.

Moving Beyond the “IBS” Label

You deserve more than a generic diagnosis and a quick fix. You deserve answers, and you deserve to feel well. If you’ve been told you have IBS, but the treatments aren’t working, it’s time to consider whether undiagnosed SIBO could be the real culprit. With the right testing, treatment, and prevention strategies, it’s possible to address the root cause of your symptoms and achieve lasting gut health.

Don’t settle for a diagnosis that leaves you in the dark. Let’s work together to uncover the true cause of your gut issues and create a plan that not only alleviates your symptoms but restores your gut health from the inside out. Remember, your gut is the foundation of your overall health, and taking care of it is the first step toward a happier, healthier life.

Apply to work with me here.