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.
The type of infection appears to matter, too. One review of nearly 50 studies involving more than 28,000 people found that 14.5 percent developed post-infection IBS after acute gastroenteritis. Broken down by infection type:
- 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.
Unfortunately, recovery is not universal. Evidence suggests that about 15 percent of adults with post-infection IBS still had ongoing symptoms after 8 years, says Sonu.
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