IBS, Post-Infectious IBS, and SIBO: What's the difference?

IBS, Post-Infectious IBS, and SIBO: What's the difference?

It's essential to know what type of IBS you have. Post-infectious IBS may be curable over time. Or you may have SIBO, which often looks very similar to classic IBS. Learn more about these 3 commonly misunderstood digestive disorders, and how to diagnose and manage them.

If you’re here, you may be familiar with IBS already. The majority of people I work with have what I call “classic” IBS, which is what I have, too. 

The process of diagnosing IBS can be challenging, because it’s more about identifying certain symptoms and narrowing down other possibilities. That set of symptoms is called the Rome Criteria. You don’t have to have every single symptom on the list, but you do have to have a majority of them. 

The other part of diagnosing IBS is ruling out conditions that can have similar symptoms. Some examples of other conditions could be celiac, colon cancer, inflammatory bowel disease, food intolerances, and so forth. All of those can look similar, so a doctor would want to do tests to rule them out. 

But once the other possibilities are ruled out, you’ll likely get that IBS diagnosis. 

Some quick facts about IBS:

  • IBS is typically categorized into IBS-D, for IBS with diarrhea, and IBS-C, for IBS with constipation, but it can be unique for each individual, and you may have a mix of both.
  • An estimated 10-15% of people have IBS, and an estimated two-thirds of them are women. 
  • It’s also estimated that IBS is under-reported in men, so the numbers could actually be closer to 50%, but we don’t know for certain.
  • IBS is the second leading cause of missed work days, after the common cold!
  • The causes of IBS are still not fully understood.
  • While some people get IBS as children, if often starts in adulthood.

Despite many of these common symptoms, criteria lists, and similar experiences, IBS is unique to everybody. If you have IBS, or suspect you may have it, then any quick look through a Facebook group or a forum online will confirm that it presents differently for everyone, and with differing severity.

Different stress triggers, food triggers, and lifestyles can make the presentation of symptoms vary widely. 

When you start to get into the FODMAP diet, it is very likely that your specific food triggers will be different from someone else’s. As you go through the process of eliminating the high-FODMAP foods, then carefully reintroducing them by category, you will find your individual tolerance levels will be specific to you, too. 

So even though IBS is one condition, it can look very different! Studies on IBS suggest that the condition does have some genetic component. If one of your parents has it, there’s a chance you might inherit it as well, even if your symptoms present differently from theirs. 

(Rather watch? Scroll to the end for the video that goes with this post!)

What is Post-Infectious IBS?

Now that you have a general overview of IBS, let’s look at a less common form that isn’t well understood. 

Sometimes a severe illness can alter the environment in your gut enough to cause the tell-tale signs of IBS. If your symptoms presented after some kind of an infection, you may have what’s called Post-Infectious IBS

Post-infectious IBS typically starts suddenly after you’ve experienced an infection of the stomach or intestines, also known as bacterial gastroenteritis. This initial infection can be caused by clostridium difficile (c. diff), salmonella, yersinia, E.coli, or other bacterial contaminants in food and water. 

Generally, the longer and more severe the infection, the greater the risk of developing post-infectious IBS. But the good news is, many people with PI-IBS recover completely, although this might take years.

The other good news is that the FODMAP diet is a good way to manage symptoms for both classic IBS and PI-IBS. It can improve your quality of life, and help with identifying those trigger foods, so you can avoid them.

There's also evidence that probiotics can help restore the gut microbiota, and fecal microbiota transplantation appears to be an effective treatment, particularly in people infected with c. diff.

When IBS isn’t IBS: Understanding SIBO: Small Intestinal Bacterial Overgrowth

IBS has a lot of gray areas, a lot of mysteries yet to be discovered, in terms of causes, triggers, and heritability factors. 

SIBO—which stands for Small Intestinal Bacterial Overgrowth—is a digestive condition that’s even more mysterious, frustrating, and challenging to diagnose. The reason for this is that it looks a lot like IBS, in terms of symptoms: 

  • Heartburn (due to low acid, not high!) 
  • Gas
  • Bloating
  • Cramping
  • Indigestion
  • Diarrhea or constipation
  • Food intolerances

There is a breath test for SIBO, but unfortunately it can give both false positives, and false negatives. It’s not entirely reliable, which is why some doctors might not consider it as an option to begin with. 

Unlike IBS, these symptoms, and others, are caused by the overgrowth of intestinal bacteria. Because this bacteria can be brought back into balance, unlike classic IBS, you can, potentially, recover from SIBO. 

Some of the suggested causes of SIBO include:

  • Very slow gut motility. Food is moving through your digestive system slower than normal. 
  • Structural abnormality of the digestive tract, which may be causing this slow gut motility.
  • A condition that causes damage to the nerves and muscles of the gut, such as Diabetes Mellitus or Scleroderma.
  • Scarring on the small intestine, either from prior surgery to the digestive tract, or from Crohn’s disease.
  • Low stomach acid production, due to acid-blocking medications, infection, or just due to your own biology.

So since IBS and SIBO tend to present with similar symptoms, how do you know you might have SIBO, rather than IBS? 

One indicator that you might have SIBO is if you’ve been following the FODMAP diet for a while, eliminating those specific foods, and you’re really not seeing much, if any, improvement. Some other signs or indicators are: 

  • Low stomach acid, or if you’re currently taking acid-blocking drugs
  • A vitamin b12 deficiency, as this is one of the things harmful bacteria feed on
  • Difficulty digesting fat
  • The presence of certain associated conditions—which is not to suggest that these cause SIBO, but that they are associated. 

Taking the Next Steps

If you believe you may have SIBO, I highly recommend talking to a medical professional about diagnosis and treatment options.  It is a complex condition and can be challenging to diagnose, let alone treat. 

There is at present one well-received antibiotic treatment for SIBO (Rifaximin combined with Neomycin), but many of my clients who have taken it say that it’s expensive, and rarely covered by insurance. 

An alternative to this antibiotic is taking a botanical antimicrobial. But, again, talk to your doctor. If you don’t know where to begin, the SIBO Center for Digestive Health provides resources to learn more about diagnosis and testing.

And if you’re not sure whether your digestive issues are a result of SIBO, IBS, post-infectious IBS, or something else entirely, your next steps are to talk to your doctor and ask what options are available to you, in terms of testing and diagnosis. 

Dietary Treatment for IBS

Consider asking your doctor if the FODMAP diet might be a good choice for you. Since both IBS and post-infectious IBS can see a reduction of symptoms following the FODMAP diet, it’s certainly worth trying! 

For more information on how to get started AND be successful on the FODMAP Diet, click here to sign up for our free 7-Day Calm Belly Challenge