SIBO vs. IBS: What’s Causing Your Bloating and How to Test It
- Xenia
- Apr 16
- 2 min read
Bloating, gas, abdominal pain, and irregular bowel movements—sound familiar? If you’ve been told you have Irritable Bowel Syndrome (IBS), you’re not alone. IBS affects an estimated 10–15% of the population. But what if your IBS diagnosis is actually masking something deeper—like SIBO?
Small Intestinal Bacterial Overgrowth (SIBO) is an often-overlooked root cause of IBS-like symptoms. Understanding the difference between SIBO and IBS is essential for effective treatment and long-term relief. Let’s break it down.
What is IBS?
Irritable Bowel Syndrome (IBS) is a functional gastrointestinal disorder characterized by symptoms such as:
Bloating
Abdominal discomfort or cramping
Diarrhea, constipation, or alternating patterns
A sense of incomplete evacuation
IBS is considered a "diagnosis of exclusion," meaning it’s diagnosed when no structural cause can be found for the symptoms. It’s often managed with dietary changes, stress reduction, and medications for symptom control—but not necessarily cured.
What is SIBO?
SIBO stands for Small Intestinal Bacterial Overgrowth. It occurs when bacteria that normally reside in the large intestine start multiplying in the small intestine—where they don't belong. This bacterial overgrowth ferments carbohydrates prematurely, leading to:
Excessive gas production
Bloating soon after eating
Belching and flatulence
Abdominal pain
Diarrhea, constipation, or both
Nutrient malabsorption
Interestingly, research shows that up to 70% of IBS cases may actually be due to SIBO. This explains why many patients diagnosed with IBS don’t get better with standard treatments.
Key Differences Between SIBO and IBS
Feature | IBS | SIBO |
Cause | Unknown/functional | Bacterial overgrowth |
Onset | Gradual or stress-induced | Often post-infection, surgery, or food poisoning |
Symptoms | Bloating, pain, bowel irregularities | Bloating after meals, excessive gas, pain, foul-smelling stool |
Testing | No standard diagnostic test | Breath testing for hydrogen/methane |
Treatment | Diet, stress management, symptom-targeted meds | Targeted antimicrobial therapy + root cause resolution |
How to Test for SIBO
The gold standard for SIBO testing is a non-invasive breath test using glucose or lactulose as a substrate. Here’s how it works:
Preparation: You’ll follow a special diet the day before and fast overnight.
Testing: You’ll drink a sugar solution (lactulose or glucose).
Breath Samples: Breath samples are collected every 15–20 minutes for 2–3 hours.
Analysis: Elevated levels of hydrogen or methane gases indicate bacterial fermentation in the small intestine.
Some labs also test for hydrogen sulfide, which may cause symptoms like fatigue, diarrhea, and sulfur-smelling gas—often missed in traditional testing.
Why Proper Diagnosis Matters
Treating IBS with symptom-relieving medications may provide temporary relief, but if the root cause is actually SIBO, it often comes back. Identifying and treating SIBO appropriately can:
Reduce bloating and abdominal pain
Normalize bowel habits
Improve nutrient absorption
Decrease systemic inflammation
Improve mood, energy, and skin health
What’s Next?
If you suspect SIBO may be the real reason behind your “IBS,” don’t guess—test.
Xenia, Your Functional Medicine NP, offers advanced breath testing and personalized treatment protocols to uncover and address the root cause of your gut symptoms. From targeted herbal antimicrobials to gut-healing diets and motility support, we guide you step-by-step toward lasting relief.
Ready to Beat the Bloat?
📍 Schedule a complimentary discovery call
Order your SIBO test kit directly to your home & work with a provider in Austin who gets to the root. Serving patients in Austin, Dallas, Houston and the entire State of Texas.
Yours in health,
Xenia, Your Functional Med NP
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