Is It IBS… Or Is It Actually SIBO?
Many people are diagnosed with irritable bowel syndrome (IBS) after experiencing symptoms like bloating, gas, abdominal pain, diarrhea, or constipation.
But IBS is not a single disease. It’s a diagnosis based on symptoms, often given when other conditions have been ruled out. That means two people with IBS may actually have very different underlying causes driving their symptoms.
One possibility that has gained significant attention in recent years is small intestinal bacterial overgrowth (SIBO).
What Happens in SIBO
The digestive tract contains trillions of microbes, but their location matters. The large intestine is meant to contain most of the gut’s bacteria. The small intestine, where most nutrient absorption occurs, normally contains far fewer microbes. SIBO occurs when bacteria that normally belong in the large intestine begin multiplying in the small intestine.
When this happens, those bacteria start fermenting carbohydrates earlier in digestion, producing gases such as hydrogen and methane. This gas production can lead to symptoms like bloating, abdominal pressure, and irregular bowel movements.
Why IBS and SIBO Look So Similar
Because bacterial fermentation produces gas and alters gut motility, SIBO symptoms often overlap almost perfectly with IBS. Research suggests that a large percentage of people diagnosed with IBS may actually test positive for SIBO, with some estimates reaching up to 70%.
This doesn’t mean every case of IBS is SIBO. But it does suggest that IBS may sometimes describe the symptoms, while SIBO represents the underlying mechanism.
Symptoms That May Point Toward SIBO
Some patterns tend to appear more frequently when bacterial overgrowth is present:
• bloating that worsens after eating
• abdominal distension that increases throughout the day
• excessive gas or pressure
• constipation, diarrhea, or both
• feeling overly full after small meals
• probiotics making symptoms worse
These symptoms can occur because fermentation and gas production are happening in the wrong part of the digestive tract.
Why Identifying the Cause Matters
When digestive symptoms are labeled broadly as IBS, treatment often focuses on symptom management. But when an underlying mechanism like bacterial overgrowth is identified, it can provide a clearer direction for treatment. Understanding what may be happening in the gut is often the first step toward improving digestion and reducing chronic symptoms.
If persistent bloating, irregular digestion, or discomfort after meals sounds familiar, further evaluation may help determine whether bacterial overgrowth could be contributing to symptoms.
