Food Poisoning Can Trigger IBS That Lasts for Months, Sometimes Years

For some people, an episode of food poisoning can leave behind more than a bad memory. Long after the acute infection has passed, stomach cramps, diarrhea, constipation, and other symptoms can keep happening, sometimes for months or even years.

“It is certainly possible that the incidence will increase with the uptick of foodborne illnesses this summer. About 10 percent of those who suffer from a gastrointestinal illness will go on to develop post-infectious IBS,” says Irene Sonu, MD, a clinical associate professor of medicine in gastroenterology and hepatology at Stanford Medicine in California.

What Is Post-Infection IBS?

William D. Chey, MD, chief of the gastroenterology and hepatology division at Michigan Medicine in Ann Arbor, says it helps to understand what the gut is doing during the original infection.

“When you get an acute infection in the GI [gastrointestinal] tract, whether it be a bacteria, a virus, or a parasite, the reason why there is such a violent reaction — diarrhea, abdominal cramping, and oftentimes nausea and vomiting — is because your body is trying to get rid of the infection as quickly as possible,” says Dr. Chey.

Normally, those reactions stop occurring once the infection clears. “But in post-infection IBS, that doesn’t happen. It’s almost like a hangover in your GI tract. The alcohol is gone, the acute effects of the alcohol are gone, but now you have this hangover that just persists,” Chey says.

• Abdominal pain
• Bloating
• Gas
• Diarrhea
• Constipation
• A combination of diarrhea and constipation

There isn’t a specific test that confirms post-infection IBS, says Chey. Instead, doctors may test for an ongoing infection or another condition that could explain the symptoms.

“For someone with acute or persistent diarrhea, that can include a stool PCR test or stool culture to look for organisms such as Salmonella, Shigella, or Campylobacter [all common types of bacteria that can cause food poisoning], particularly when diarrhea is bloody,” he says.

How Can Food Poisoning Cause IBS?

It’s not really clear why some people recover completely from a gastrointestinal infection while others are left with lasting digestive symptoms, says Chey.

“There are a bunch of different theories,” he says. Among the possibilities Chey points to:

• An immune and nervous system that stays activated. During an infection, both systems in the gut become highly active. For some, these systems may not fully return to normal after the infection clears.
• Changes in the gut microbiome or intestinal barrier. An infection may alter the bacteria living in the gut or make the intestinal lining more permeable, allowing substances inside the intestine to interact more readily with immune cells and nerves in the gut wall.
• An autoimmune response after certain bacterial infections. Some infections may trigger antibodies that mistakenly attack nerves involved in controlling movement in the gut.

While it isn’t known which theory may be correct, the overarching issue is that the gut has become sensitized, says Dr. Sonu.

Who Is Most Likely to Develop Post-Infection IBS?

Researchers have identified a few factors that may increase the risk of food poisoning or another GI infection developing into post-infection IBS.

“The first thing is the duration and severity of the infection. The more severe the infection is, and the longer it goes on, the more likely you are to develop this problem,” says Chey.

In addition, women are more likely than men to develop post-infection IBS, he says.

• About 30 percent of participants developed post-infection IBS after parasitic infections
• About 18 percent after bacterial infections
• About 11 percent after viral infections

Chey says higher rates have been reported after infections caused by Giardia, Campylobacter, and Salmonella.

It’s not clear what the impact of this summer’s Cyclospora outbreak will be, he says. “We really don’t know what the rate of post-infection IBS is in association with Cyclospora.”

Chey’s team is following people who developed Cyclospora infections in Michigan to try to answer that question, but the results will be a few years away.

How Do Doctors Treat Post-Infection IBS?

Post-infection IBS treatment can involve a number of approaches, Sonu says, and the best therapy can depend on the symptoms. She typically recommends:

• For diarrhea: Antidiarrheal medications, certain antibiotics, or bile acid binders
• For constipation: Laxatives
• For either diarrhea or constipation: Soluble fiber supplements
• For cramping: Prescription or over-the-counter antispasmodic medications
• For the gut-brain connection: Cognitive behavioral therapy or gut-directed hypnotherapy, sometimes with the help of a therapist or smartphone app
• For food-related symptoms: A low-FODMAP diet, which temporarily limits certain carbohydrates that are fermented in the gut and can draw fluid into the intestines

A Mediterranean diet may also improve symptoms for some people, says Chey. While some people may need to temporarily follow a restrictive diet, the goal is to gradually reintroduce foods so they can tolerate a normal diet again, she says.

Will Post-Infection IBS Eventually Go Away?

“At least half the patients resolve, or just spontaneously get better over time,” Chey says. It may take months and sometimes even years, but things will gradually go back to normal, he says.

That possibility of recovery is one reason it matters whether IBS began after an infection, Chey says. Compared with people whose IBS wasn’t triggered by an infection, people with post-infection IBS appear more likely to eventually experience remission.