The one saving grace when it comes to a stomach bug is that it’s typically short-lived. The brutal nausea and vomiting of norovirus, for instance, subsides in one to three days; even the relentless diarrhea of cyclosporiasis can let up in a couple of days with an antibiotic. But after certain gut infections, once the most intense symptoms have resolved, GI troubles can linger, turning into chronic bowel issues and pain. That’s the usual course of post-infection irritable bowel syndrome (PI-IBS).
As many as 1 in 10 people who have had some type of gastrointestinal infection go on to develop PI-IBS, research suggests.
At first, you might suspect that you’re just not getting over the initial bug — but in reality, the infection “causes damage to the lining of the GI tract, which then subsequently causes the nerves in the gut to become more sensitive,” said Kyle Staller, a gastroenterologist and director of the Gastrointestinal Motility Laboratory at Mass General. That can translate to irritable bowel syndrome (IBS), he said, which is characterized by a disconnect in communication between the brain and the gut that causes the brain to perceive normal gut contractions as painful.
The symptoms of PI-IBS mirror those of typical IBS, defined by recurrent abdominal pain related to defecation and changes in stool frequency and form, such as diarrhea or constipation. You might also deal with cramping, bloating or gas.
A doctor can diagnose PI-IBS by simply asking about your symptoms and recent medical history — so long as you don’t also have any “alarm symptoms,” like bloody stools or unexplained weight loss, which trigger the need for testing to rule out other conditions, Staller said. Any IBS diagnosis also entails having the related symptoms consistently for at least three months.
Read on to learn more about what causes post-infection IBS, who is most at risk and how to find relief.
What causes post-infection irritable bowel syndrome?
Though it isn’t fully clear why it occurs, experts have identified a couple of ways it can happen.
For starters, an infection — whether it’s caused by a bacterium, virus or parasite — can disrupt the gut microbiome, or the community of microbes that populate the GI tract. “This can be a result of the infection itself, for example, diminishing some of the healthy bacteria, and it can also be caused by how the infection changes the gut lining, so that certain bacteria are more happy to live there than others,” Staller explained. An altered microbiome can then lead to shifts in gut function and the gut nerves, setting the stage for IBS symptoms.
There’s also evidence that a stomach bug may cause the gut lining to become more permeable, allowing substances in the gut such as bile acid, nutrients and by-products of microbes to slip into the bloodstream, said Lin Chang, a gastroenterologist and director of the Walter and Shirley Wang Center for Integrative Digestive Health at UCLA Health. As the gut’s main layer of protection breaks down, the immune system launches a response, releasing chemicals that “act on the nerves in the gut and cause them to increase their firing,” Chang said.
Who is most at risk for PI-IBS?
Several groups who are generally at higher risk for IBS are also at elevated risk for the post-infection type, including women, young people and those with mental health conditions such as anxiety or depression. “The GI infection may be just the straw that breaks the camel’s back and brings out that underlying predisposition,” Staller said.
Experiencing psychological distress while having a stomach bug may also raise the chance that you wind up with PI-IBS afterward, Chang said. This kind of mental state can shift the way the brain reads signals from the gut and responds to them, she explained, which could make you more susceptible to a breakdown in that communication. Stress can also increase intestinal permeability, making your gut less resilient in the face of an infection, she added.
More severe, long-lasting GI illnesses — often caused by parasites and bacteria rather than viruses — are also linked to a greater risk of developing PI-IBS, probably because they can cause more damage to the gut lining, Staller said. Parasitic infections, in particular, can also wax and wane for a while in ways that might make people delay seeking treatment, Chang pointed out. The more time a parasitic infection goes untreated, the more of an impact it can have on your system — which may then increase the likelihood that you get stuck with PI-IBS.
To note, it’s not clear yet if there will be a surge in PI-IBS cases after this summer’s cyclosporiasis outbreak; researchers are currently investigating to learn more.
What is the treatment for post-infection IBS?
Some good news: While typical IBS is considered a lifelong condition, “there’s evidence to suggest that PI-IBS generally gets better with time,” Chang said, though that could take anywhere from several months to a few years.
Treatment looks mostly the same as it does for typical IBS, which typically starts with dietary adjustments, Chang said, for instance identifying and limiting trigger foods. These are often foods high in FODMAPs — a type of fermentable carbohydrate — such as onions, garlic, wheat-based products and dairy. (It’s best to work with a registered dietitian before diving into a full-scale low-FODMAP diet because it can involve a lot of restriction.) Ramping up fiber intake, including by taking a supplement like psyllium husk, can also help lessen mild symptoms, Staller said.
Then there are therapies that work by minimizing gut spasms, such as over-the-counter peppermint capsules and prescription medications including hyoscyamine and dicyclomine, which Chang said can help with abdominal pain.
And finally, a slate of different medications are geared more specifically toward either diarrhea- or constipation-predominant types of IBS. Research suggests most people with PI-IBS have a mixed version (and deal with both issues), followed by diarrhea, then constipation.
The main diarrhea solutions include the prescription eluxadoline, which slows down the bowels, and rifaximin, a minimally absorbed antibiotic. Some doctors also recommend neuromodulators called tricyclic antidepressants, which aren’t used much for depression these days but may help IBS by improving nerve signaling, Staller said. Popular constipation options include the prescription medications lubiprostone and linaclotide, which enhance the secretion of chloride into the gut to help raise fluid levels and move stool along, Chang said.
The ideal protocol for you may be any one or a combination of the above. What’s important is to take note of GI symptoms that linger for more than a couple of weeks after a gut infection and flag them to your doctor, Chang said. There’s a chance you’re dealing with a different beast than the original infection — and need a different kind of care to tackle it.
If that’s the case, Staller said, remember that “there’s hope” when it comes to PI-IBS that you will ultimately recover with time, “even if you feel like you’ve exhausted all your options.”
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