IBS, IBD, SIBO: What’s the Difference?

This original article and video interview with Dr. Gary Weiner was published on December 11, 2018 by Shivan Sarna at sibosos.com. It is the third part of our new series of posts on IBS, IBD, and SIBO highlighting previous articles that are still very relevant in 2019.


This post and interview with Dr. Gary Weiner introduce you to the differences and relationship between the conditions of IBS, IBD and SIBO. If you have been diagnosed with one or a combination of these conditions this interview will help you understand how they may be related and help you to understand how to get effective treatment to help you get healthy again.

The previous posts in the series were about Treating IBD. Look forward to additional articles in this series on the Use of Elemental Diets in IBS and IBD, and additional videos and summary articles including posts related to Chinese Medicine and Acupuncture as treatments for IBS, IBD, and SIBO.

Gary Weiner, ND, LAc

If you’re having digestive problems, you have enough to deal with without having to keep a bunch of acronyms straight.

But if you go visit your doctor – or do some research on your own – you’ll find a LOT of acronyms – and three of them more than any others: IBS, IBD, and SIBO.

IBS stands for Irritable Bowel Syndrome, IBD for Inflammatory Bowel Disease, and SIBO for Small Intestine Bacterial Overgrowth.

Today, I want to teach you not just what each of these important acronyms means, but what the difference between each is – and, most importantly, how they are all related.

Understanding the link between Irritable Bowel Syndrome, Inflammatory Bowel Disease, and Small Intestine Bacterial Overgrowth can help you get the right treatment the first time.

If your doctor has told you or someone you love that you have any of these conditions (or even if you just suspect it), keep reading.

What Is IBS?

IBS stands for Irritable Bowel Syndrome.

In Western medicine, “syndrome” is a way of classifying a group of symptoms. Think Chronic Fatigue Syndrome or Restless Leg Syndrome.

In almost any syndrome, doctors use what is called a diagnosis of exclusion. A diagnosis of exclusion just means that there is no other physical explanation for a person’s symptoms.

Imagine you go visit your doctor with stomach pain and diarrhea. They might refer you to a gastroenterologist who performs tests to check for pathological issues, something like Celiac Disease or an ulcer. But if all those tests come back negative  – yet you still have symptoms – you might be told you IBS.

The most common symptom patterns in IBS are abdominal pain, bowel motility disruption like spasms or gastroparesis, diarrhea, constipation (or alternating between both) and pain, bloating and discomfort.

Doctors use something called the Rome Criteria to define what type of IBS a person has:

  • Predominantly diarrhea
  • Predominantly constipation
  • Mixed constipation and diarrhea
  • Post-infectious

(Just FYI – there is some controversy about the Rome Criteria. Not all doctors think it is useful.)

Depending on what type of IBS you have, your doctor might suggest medications or other treatments that can make the symptoms go away or be less severe.

What Is IBD?

Unlike IBS,  IBD (Inflammatory Bowel Disease) is a pathological disease.

That means that there is a pathology  – AKA a cause – for the symptoms that doctors can find.

It gets confusing because IBS and IBD can cause the same symptoms: abdominal pain, constipation and diarrhea, and bloating (to name a few!). But IBS and IBD are different.

Imagine you’re back at your doctor with symptoms. They refer you to a gastroenterologist who performs more tests. But this time, not all the tests come back negative: instead, tests show you have an Inflammatory Bowel Disease.

There are two inflammatory bowel diseases: ulcerative colitis and Crohn’s Disease.

Ulcerative colitis (UC) causes inflammation on the mucosa of the colon. This can cause severe diarrhea, blood in the stool, and lots of pain.

Crohn’s Disease causes inflammation throughout the entire digestive system – anywhere from your mouth to your anus – but the inflammation goes deeper than it does in ulcerative colitis. This is called intramural inflammation.

Treatments for IBD include both medications to manage symptoms (sometimes the same ones used for IBS) and to treat the inflammation in the digestive system.

Why IBS & IBD Aren’t Totally Same OR Different

You might be thinking that it sounds like IBS and IBD are totally different. You either have IBS or you have IBD.

But that actually isn’t all true.

In fact, according to naturopathic physician Dr. Gary Weiner, IBS and IBD are more likely two different ends of the same continuum.

Both IBS and IBD have overlapping features. And even more importantly: the same person can have both IBS and IBD.

This can be confusing for both people with IBS and IBD and for their doctors. They might wonder why treatments don’t seem to be working or why some symptoms went away and others didn’t.

While IBS and IBD can cause similar symptoms, the treatment needed for each can be totally different in some cases  – that’s why figuring out which symptoms are part of IBD and which are caused by IBS is a crucial step in the healing process.

Does That Mean IBS Causes IBD?

Right now, doctors can’t say for certain that IBS and IBD exist on a continuum or that one could cause the other.

But there is evidence to support the idea.

IBS and IBD can have overlapping features like causing:

  • Production of inflammatory cytokines
  • Alterations in the microbiome
  • Inflammation at levels not detectable by colonoscopies or or other standard tests

This evidence has led some experts – like Dr. Weiner – to question if IBS is a precursor to IBD.

After all, many people who are diagnosed with IBD have struggled for years with IBS symptoms – or even have a formal IBS diagnosis. Their tummy troubles seem to have “escalated” into either UC or Crohn’s.

And, just because someone has IBD doesn’t mean they can’t also have IBS. Sometimes people with IBD have an increase of symptoms like diarrhea, pain, gas and bloating. But when they are tested for elevated levels of fecal calprotectin or fecal lactoferrin (two signs of inflammation), results come back normal. This means their IBD isn’t active or “flaring” – they are just having IBS symptoms.

Of course, not everyone who has IBS develops IBD – and not everyone with IBD had IBS symptoms first. But there’s another thing IBS and IBD have in common, too.

What Does SIBO Have To Do With IBS And IBD?

You just learned that IBS and IBD can overlap. Now, imagine 2 circles drawn so they overlap – a Venn diagram. One is labeled IBS, and the other is labeled IBD. Right in the middle where the overlap occurs, that’s SIBO.

SIBO stands for Small Intestine Bacterial Overgrowth, and it can be both a cause and an outcome of IBS and IBD.

SIBO researcher Dr. Mark Pimentel has demonstrated that SIBO is often a root cause of IBS.

And SIBO is also often present in people who have an IBD.

So what’s the difference?

While SIBO is a known cause of Irritable Bowel Syndrome, with Inflammatory Bowel Disease, it’s the other way around: Inflammatory Bowel Disease can cause SIBO.

Let me repeat that because it can be confusing:

SIBO can cause Irritable Bowel Syndrome.

Inflammatory Bowel Disease can cause SIBO.

Is SIBO The Chicken Or The Egg?

SIBO or IBSJust like the question of the chicken and the egg can be very confusing if you think about it too much, so can the relationship between IBS, IBD, and SIBO.

SIBO is often the cause of Irritable Bowel Syndrome. While there are many other potential causes for IBS, and not everyone with IBS has SIBO, it is estimated that as much as 84% of people who have IBS have SIBO, too.

But there actually isn’t any evidence that SIBO causes Inflammatory Bowel Disease. In fact, it seems to be the other way around: having an IBD can cause SIBO to develop.

The inflammation caused by IBD can create an opportunity for SIBO to develop when normal motility is disrupted.

In basic terms, this just means that when inflammation brought on by UC or Crohn’s causes the digestive system to either slow down (constipation) or speed up (diarrhea), bacteria has a chance to overgrow in the small intestine.

IBD can also interfere with the function of the migrating motor complex (MMC). The MMC is responsible for moving food through the digestive system – some people think of it like a broom sweeping food down the digestive system. When the MMC is interrupted, SIBO can occur.

Why The IBS-IBD-SIBO Link Is So Important

I know that everything we’ve covered so far has been complex and sometimes confusing – but it is really important to understand how Irritable Bowel Syndrome, Inflammatory Bowel Disease, and Small Intestine Bacterial Overgrowth are all related if you want to get healthy again.

If you have SIBO, you (or your doctor) might be confusing it with Inflammatory Bowel Disease. If you IBS, your doctor may not realize it is being caused by SIBO. And if you have Inflammatory Bowel Disease, you might also develop SIBO.

Knowing this is so important for getting effective treatment.

Treating the SIBO within Inflammatory Bowel Disease can help you get better faster and go into remission from IBD. For some people, treating SIBO can cause all IBS symptoms to disappear. And if IBS does often to lead to BID later on, getting IBS under control is even more important.

If you have symptoms of IBS, IBD, or SIBO it’s very important to find out which condition is causing what symptoms. If you treat the SIBO as IBS or the IBD as IBS, you wind up very frustrated and not healing.

Take Ownership & Find The Right Treatment For You

Whether you have Irritable Bowel Syndrome, Inflammatory Bowel Disease, SIBO, or a combination of all three, there is hope for healing and remission.

But, healing starts with become educated and empowered about what is happening to your body! Just like I did, you need to take ownership of your health. That means asking questions, researching, and staying informed.

After all, if you won’t advocate for yourself, who will?

That doesn’t mean you have to become the expert on SIBO, IBS, or IBD. Fortunately, there are many other people who already ARE experts on these complex topics – and they’re willing to share their knowledge with us so we can finally get better.

Dr. Gary Weiner, IBD, IBS, SIBOSee the interview and read the full text of the original article here

Dr. Gary Weiner, ND. L.Ac. is the medical director of Pearl Natural Health in Portland, Oregon, where he has developed an alternative and complementary care program for inflammatory bowel disease. He graduated from NCNM in 1997 and completed a 1-year residency in family medicine. He has served as adjunct faculty and clinical supervisor at NCNM, and is on the medical advisory board of the Northwest Crohn’s and Colitis Foundation of America. He is a sought after speaker and lecturer on IBD< IBS and SIBO, speaking to both naturopathic and conventional medical doctors. Dr Weiner lives with his wife and daughter.

  1. I found it interesting that you state that if you have both IBD and IBS the symptoms will be different and will require separate medicines to control them. My brother has been having severe stomach cramps and wants to get rid of them as soon as possible. I will send him this information so he can start looking for a gastroenterologist to help him out.

  2. I believe my SIBO is caused by my Selective IgA deficiency which, I believe also caused my Cold Agglutinin Disease and my Achlorhydria (and low stomach acid probably causes my high Candida overgrowth and gut microbiome imbalance).

  3. OOPs correction, as you said symptoms get confusing and I am still learning. I think my Selective IgA deficiency caused both my SIBO and my CAD/Cold Agglutinin Disease. And my achlorhydria influences or causes my high Candida overgrowth and gut microbiome imbalance. My major gut symptoms are bloating and stomach distention without diarrhea or constipation (though my stool moves toward pebbles on and off, this is not constipation– meaning not passing stool for two or three days is not my problem. Watching food quantities and restricting FODMAP foods helps. Stopping the gut distention and preventing gastrointestinal cancer due to inflammation is my main goal. Do you think it is important to also test for IBS or IBD in my situation? It seems a waste of time and money if nothing more can be done for me. Thank you for teaching me the difference between SIBO, IBD and IBS.

  4. I am currently on a 2nd round of xifaxan and I take a probiotic. But why do I still have issues with smelly gas, either diahrrea or constipation, major bloating. One note I lost a ft of my colon 10.5 yrs ago from cancer, no gallbladder and have reflex issues. Can these be a part of my problem I am desperate for some help. I am 77 yrs old but very healthy otherwise.

  5. how do i get tested for these

  6. This was such an interesting read I was diagnosed with IBS a year ago and since my symptoms are getting worse and worse and changing into a bigger range all the time. It is now affecting my quality of life and I don’t know what to do.

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