Key Symptoms of IBS vs SIBO – What’s the Difference?
If you’ve ever been told you have “Irritable Bowel Syndrome” (IBS), you might have walked out of the doctor’s office thinking… Okay, but what does that actually mean?
The truth is, IBS is a bit of an umbrella term. It’s used to describe a group of gut symptoms—like bloating, diarrhea, constipation, or stomach pain—without necessarily explaining why those symptoms are happening. Think of it as a label for the experience, not the root cause. And that’s where a lot of people feel stuck—because knowing you have IBS doesn’t always tell you what’s actually wrong or how to fix it.
One of the most common hidden causes of IBS? Small Intestine Bacterial Overgrowth (SIBO). And while SIBO can look a lot like IBS from the outside, it’s actually something very specific—and treatable.
Let’s break down the differences.
IBS – More of a “symptom collection” than a single diagnosis
IBS isn’t a disease on its own—it’s a diagnosis given when you’ve had ongoing gut symptoms for at least 3 months, but testing hasn’t revealed anything obviously wrong (like celiac disease, Crohn’s, or cancer).
Common IBS symptoms include:
Bloating (often worse after meals)
Abdominal cramping or discomfort
Diarrhea, constipation, or a mix of both
Mucus in the stool
A feeling that you haven’t fully emptied your bowels
Here’s the tricky part: IBS is actually caused by many different underlying issues. You could line up ten people with an IBS diagnosis, and each of them might have a completely different root cause. Some examples:
Stress-induced IBS – The gut and brain are closely connected. Chronic stress or anxiety can make the nerves in your gut hypersensitive, leading to cramping, urgency, and changes in bowel movements.
Leaky gut – When the lining of your intestines becomes more permeable than it should be, it can cause immune reactions, inflammation, and gut discomfort.
Food sensitivities – Certain foods can trigger symptoms in some people, especially fermentable carbs (known as FODMAPs).
Gut motility issues – If the muscles in your intestines aren’t moving food along properly, you can get backed up—or things can move too quickly.
The point is: IBS is a label, not the whole story. Which means if you’ve been told you have IBS, the next step is finding out why.
SIBO – A specific (and very common) cause of IBS
SIBO stands for Small Intestine Bacterial Overgrowth—and it’s exactly what it sounds like. Normally, your small intestine has relatively few bacteria compared to your large intestine. In SIBO, those bacteria start growing where they shouldn’t—up in the small intestine—where they ferment your food and cause a lot of uncomfortable symptoms.
Here’s why it matters: research shows that up to 60–70% of people with IBS actually have SIBO as the root cause.
SIBO can be triggered by things like:
Food poisoning or gut infections
Abdominal surgeries (scar tissue can affect motility)
Low stomach acid or poor bile flow
Chronic stress slowing down the gut
Conditions like hypothyroidism or diabetes that affect motility
How IBS and SIBO symptoms can look the same… but also different
Symptoms they both share:
Bloating (often within 30–60 minutes of eating)
Gas
Abdominal discomfort or cramping
Changes in bowel movements (constipation, diarrhea, or both)
Symptoms that can be more specific to SIBO:
Bloating that’s extreme or makes you look “six months pregnant” by the end of the day
Symptoms that flare significantly after eating certain carbs (especially beans, onions, garlic, bread, or fruit)
Frequent burping or reflux
Nutrient deficiencies over time (especially B12, iron, and fat-soluble vitamins)
Testing for SIBO
Unlike IBS—which is diagnosed based on symptoms—SIBO can be tested for. The most common method is a breath test, where you drink a sugar solution (like lactulose or glucose) and then measure the gases your body produces over a few hours.
The bacteria in your small intestine produce hydrogen or methane (or both), which show up in your breath. Different gas patterns can even tell us whether your SIBO is more likely to cause diarrhea, constipation, or mixed symptoms.
The good news: SIBO can be treated
One of the most frustrating things about an IBS diagnosis is that you’re often told to “just manage your symptoms” with diet changes or medication. But with SIBO, there’s a clear treatment path that aims to remove the overgrowth and restore gut health.
Treatment typically involves:
Reducing bacterial overgrowth – This can be done with specific herbal antimicrobials for SIBO.
Supporting motility – Using prokinetics, stress management, or dietary timing to keep food moving through the gut.
Repairing and rebuilding – Healing the gut lining, supporting digestion, and preventing recurrence.
Many people feel dramatic relief once SIBO is treated—sometimes after years of thinking they were just “stuck” with IBS.
Bottom line: You don’t have to just live with it
If you’ve been told you have IBS, it’s worth digging deeper to find out why. Whether it’s SIBO, stress, food sensitivities, or something else entirely, there are ways to treat the underlying cause—not just mask the symptoms.
And if it turns out to be SIBO? You’re in luck. It’s one of the most common (and treatable) root causes of IBS. The right testing and a targeted treatment plan can help you get back to feeling like yourself—without the daily bloating, discomfort, and bathroom surprises.
Your gut is talking to you. The next step is figuring out what it’s trying to say—and that starts with asking the right questions.
Ready to make a change?
Book a complimentary 15-minute consult to learn how naturopathic care can help you determine what’s happening with your digestive health and address these symptoms with confidence. We’ll discuss your concerns, review what testing might be helpful, and explore personalized strategies to support your digestion, energy, and long-term health.
Be well,
Dr. Mitchell Schroeder, ND