top of page

Symptoms Quiz

Is Your Diarrhea Caused by IBS?

Take a short quiz to find out if an antibody blood test for IBS is recommended for you.

What Is Chronic Diarrhea?

Diarrhea refers to bowel movements (stool) that are loose and watery. If you have loose stools three or more times in one day, you have diarrhea.

There are three main types of diarrhea:


Acute diarrhea - lasts less than two weeks. Many people experience acute diarrhea once or twice a year, and it can be treated with over-the-counter medications.


Persistent diarrhea - lasts two to four weeks. Traditionally, people will experience loose bowels for only 14-30 days. 

Chronic diarrhea - lasts four weeks or more - can indicate a serious chronic disorder, such as inflammatory bowel disease (IBD) or irritable bowel syndrome (IBS). (Read about the difference between the two.)

Chronic diarrhea symptoms may be continual or they may come and go. Regardless, they can have an enormous impact on your mental, emotional, and social health. 

The sooner you can identify the cause for your chronic diarrhea and receive a confident diagnosis, the sooner you can begin the right treatment for you.

For more information about the types of diarrhea, along with diagnosis and treatment recommendations, please read the ACG guidelines for diarrheal infections.


What Causes Chronic Diarrhea?

Damage to the intestine's epithelium (outer, protective layer) caused by a bacterial or viral infection is a very common cause of diarrhea. When the epithelium is damaged, absorption of water in the gut happens very inefficiently, resulting in the loose, watery stools associated with diarrhea. 

The development of acute diarrhea into chronic diarrhea is less understood. As noted above, chronic diarrhea can be a symptom of chronic illnesses like IBS and IBD. 

Scientists now understand one pathophysiologic sequence that identifies gastroenteritis (food poisoning) as a major root cause of diarrhea-predominant IBS (IBS-D). In fact, research has shown that 1 in 9 people who experience food poisoning go on to develop IBS with diarrhea.


In these cases, post-infectious IBS (or IBS caused by food poisoning) can develop quickly or it can develop many years after the initial infection. Patients often don't remember the original instance of food poisoning that may have led to IBS.

Epithelial Tissue pivotal in chronic diarrhea.jpg

Epithelial Tissue

What Is Traveler's Diarrhea?

The best IBS diet

Traveler's diarrhea (TD) occurs while visiting another area of the world and consuming their food and water that may contain bacteria like Escherichia coli, Campylobacter jejuni, Shigella, or Salmonella or viruses that can upset your bowels


The CDC mentions that traveler's diarrhea is usually caused by poor hygiene in kitchens and restaurants. 


Traveler's diarrhea is different from acute and chronic diarrhea in that it can be predictable. If you are traveling soon and think you are at risk of traveler's diarrhea, ask your healthcare provider about preventative measures to protect you while you travel. 

It’s important to know that patients with post-infectious IBS (or IBS caused by food poisoning) are four times more likely to contract food poisoning again either at home or abroad. Additionally, if you do get food poisoning again, it can significantly worsen your post-infectious IBS symptoms like diarrhea.

Can One Instance of Food Poisoning Lead to Chronic Diarrhea?

Yes, it can. In fact, people who've had food poisoning in the past have a 1 in 9 chance of developing IBS with diarrheal symptoms [IBS-D (diarrhea-predominant IBS) or IBS-M (diarrhea/constipation-mixed IBS)]. 


The path from food poisoning to IBS has to do with a toxin called Cytolethal Distending Toxin B, or CdtB for short. The most common bacteria that cause food poisoning like Shigella, Campylobacter, Salmonella, and E. coli. release the toxin CdtB into your body. 


When a toxin like CdtB enters your body, your immune system fights back with an antibody - in this case, your body creates anti-CdtB. CdtB looks in some ways like vinculin, a naturally occurring protein in your body that is critical for healthy gut function. Because CdtB and vinculin can look alike, your body can think it needs to fight back against vinculin, at which point it starts producing another antibody, anti-vinculin. 


The production of anti-vinculin is an autoimmune response and leads to gut nerve damage and improper functioning of the Interstitial Cells of Cajal (ICC) and Migrating Motor Complexes (MMC). When these do not function properly, your gut microbiome is disrupted. Your gut microbiome is composed of billions of bacteria in your gut that, when balanced, keep your gut healthy.


This can ultimately result in what is called post-infectious IBS. Post-infectious IBS presents itself as diarrhea-predominant and mixed-type (diarrhea with constipation) IBS and can develop a few weeks to many years after the initial infection. 

AGA Logo.png

Here is an excellent patient guide to IBS published by the American Gastroenterological Association​.

How Do I Know If I’m at Risk for Post-Infectious IBS?

Anyone can develop post-infectious IBS. According to the CDC, 48 million people get food poisoning every year in America. According to a review conducted at the Mayo Clinic of over 40 research studies, 11% (1 in 9) will develop IBS. That’s about 5 million people that will develop post-infectious IBS this year in America alone. This makes food poisoning the leading known cause of IBS.


Post-infectious IBS presents itself as IBS-D or IBS-M. Therefore, you might have post-infectious IBS if:


  • You have chronic diarrhea, traveler’s diarrhea, or mixed diarrhea and constipation symptoms;


  • You have abdominal pain and bloating;


  • You have no other serious symptoms like blood in your stool; or


  • You have had food poisoning at some point in the past. (Note: Patients may not accurately recall whether they have had food poisoning.)

How Do You Diagnose Chronic Diarrhea as Post-Infectious IBS?

Diagnosing chronic diarrhea as post-infectious IBS is possible with a doctor-ordered antibody blood test. The test measures the levels of two antibodies known to be elevated in the blood of the majority of patients with diarrheal IBS. The two antibodies measured are anti-CdtB and anti-vinculin.  If either antibody measures over the established threshold, then post-infectious IBS (diarrhea-predominant or diarrhea/constipation-mixed IBS) can be diagnosed with confidence. This is why these antibodies are called biomarkers of IBS.


The only licensed antibody blood test for IBS is ibs-smart. The test was developed by Dr. Mark Pimentel and the M.A.S.T. team at Cedars-Sinai in Los Angeles, California.  ibs-smart can quickly and accurately diagnose IBS with diarrheal symptoms, confirming the root cause of a patient’s IBS (food poisoning). 


Receiving a biomarker-based IBS diagnosis and an understanding that the root cause is a microbiome disruption caused from food poisoning can help your healthcare provider design a personalized treatment plan.


You can order the test through an online prescriber online without an appointment or download a patient-doctor discussion guide to take to your next doctor’s appointment.

Order ibs-smart Online.

No appointment necessary

You can work with a doctor online to order ibs-smart, if it’s right for you.

The online prescriber service includes:

  • A symptoms evaluation by a doctor

  • Clear and actionable results emailed directly to you

IBS-Smart Animated Video
Play Video

Prefer to work with your healthcare provider instead? Download the ibs-smart discussion guide and educational materials here

Post infectious IBS

Post-Infectious IBS

A significant volume of research shows a clear link between food poisoning and irritable bowel syndrome (IBS).

IBS Pain


While what causes SIBO is an excess of bacteria, there are many conditions that can lead to SIBO like irritable bowel syndrome.



While irritable bowel syndrome and inflammatory bowel disease share some symptoms, they are completely different illnesses. 

bottom of page