Complications of Gastroenteritis (Stomach Flu)
Health ConditionsDigestive Health

Complications of Gastroenteritis (Stomach Flu)

Complications of Gastroenteritis (Stomach Flu)
Everyday Health
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Updated on December 15, 2025
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Gastroenteritis, a common illness that’s also known as the stomach flu, causes diarrhea, vomiting, and stomach pain that usually lasts less than a week.

What you might not know is that this condition can sometimes trigger complications. Many of these issues will eventually go away, while others may linger. Read on to learn more.

Dehydration and Gastroenteritis

Dehydration is the most common complication of gastroenteritis.

 It happens because your body loses fluids and electrolytes that aren’t replaced when you vomit or have diarrhea.

Being dehydrated is especially dangerous for small children, older adults, and people with weakened immune systems.

If you have severe dehydration, you might have to go to the hospital to have fluids delivered intravenously (through an IV).

You may be able to prevent dehydration by drinking extra fluids and, in some cases, taking an oral rehydration solution.

Gastroenteritis and Long-Term Stomach Problems

Most of the time, the symptoms of gastroenteritis go away when you recover from the infection that caused your illness. Yet some people have stomach issues that stick around.

Gut Changes

Researchers have found that gastroenteritis can actually change the microbiome balance in your body.

 This means that you’ll have a decrease in the variety and quantity of good bacteria in your gut.

Postinfectious IBS

One possible complication of gastroenteritis is something called postinfectious irritable bowel syndrome (IBS), which means you might have ongoing stomach pain, bloating, or changes in bowel habits after the infection has passed.

Studies also show a greater prevalence of postinfectious IBS in people who experienced acute gastroenteritis during a norovirus outbreak.

Colitis and Crohn’s

Some people with gastroenteritis may develop an inflammatory bowel disease (IBD) such as ulcerative colitis or Crohn’s disease — conditions that cause inflammation of your digestive tract.

Researchers believe that further studies are necessary to determine the prevalence of this link.

Gastroenteritis and Reactive Arthritis

A bout of gastroenteritis can lead to reactive arthritis, a painful form of inflammatory arthritis. Reactive arthritis can occur in reaction to an infection caused by salmonella, campylobacter, yersinia, shigella, E. coli, vibrio, or other bacteria.

The incidence rate of reactive arthritis after gastrointestinal infections varies between 0 and 15 percent.

What Should You Do if You Have Signs of a Complication?

See your doctor if you think you have a complication associated with gastroenteritis. Your doctor can monitor your condition to make sure it doesn’t worsen.

The Takeaway

  • Gastroenteritis, also known as the stomach flu, usually lasts less than a week. But this condition can sometimes trigger complications.
  • Dehydration is one common complication of gastroenteritis. Other long-term effects include the development of conditions like IBS and IBD.
  • A painful condition called reactive arthritis can also occur in reaction to the stomach flu, so check with your doctor if you think you may be experiencing complications.

Resources We Trust

EDITORIAL SOURCES
Everyday Health follows strict sourcing guidelines to ensure the accuracy of its content, outlined in our editorial policy. We use only trustworthy sources, including peer-reviewed studies, board-certified medical experts, patients with lived experience, and information from top institutions.
Resources
  1. Symptoms & Causes of Viral Gastroenteritis (“Stomach Flu”). National Institute of Diabetes and Digestive and Kidney Diseases. May 2018.
  2. Dehydration. Mayo Clinic. May 2, 2025.
  3. Lupu VV et al. Emerging Role of the Gut Microbiome in Post-Infectious Irritable Bowel Syndrome: A Literature Review. World Journal of Gastroenterology. June 7, 2023.
  4. Di Re A et al. Acute Gastroenteritis in the Etiology of Inflammatory Bowel Disease: Systematic Review and Meta-analysis. Crohn's & Colitis 360. October 1, 2021.
  5. Cheeti A et al. Reactive Arthritis. StatPearls. January 2, 2023.
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Waseem-Ahmed-bio

Waseem Ahmed, MD

Medical Reviewer

Waseem Ahmed, MD, is an assistant professor of medicine in the Karsh Division of Gastroenterology and Hepatology at Cedars-Sinai Medical Center in Los Angeles and serves as Director, Advanced Inflammatory Bowel Disease Fellowship and Education within the F. Widjaja Inflammatory Bowel Disease Institute.

He received his undergraduate degree from the University of Michigan and attended medical school at Indiana University. He then completed an internal medicine residency at New York University, followed by a fellowship in gastroenterology and hepatology at Indiana University, and an advanced fellowship in inflammatory bowel disease at the Jill Roberts Center for Inflammatory Bowel Disease at New York-Presbyterian Hospital/Weill Cornell Medicine. Prior to his current role, Dr. Ahmed served as an assistant professor of medicine within the Crohn’s and Colitis Center at the University of Colorado from 2021-2024.

Dr. Ahmed is passionate about providing innovative, comprehensive, and compassionate care for all patients with inflammatory bowel disease (IBD). His research interests include IBD medical education for patients, providers, and trainees; clinical trials; acute severe ulcerative colitis; and the use of combined advanced targeted therapy in high-risk IBD.

He enjoys spending time with his wife and dog, is an avid follower of professional tennis, and enjoys fine dining.

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Julie Lynn Marks

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Julie Marks is a freelance writer with more than 20 years of experience covering health, lifestyle, and science topics. In addition to writing for Everyday Health, her work has been featured in WebMD, SELF, Healthline, A&E, Psych Central, Verywell Health, and more. Her goal is to compose helpful articles that readers can easily understand and use to improve their well-being. She is passionate about healthy living and delivering important medical information through her writing.

Prior to her freelance career, Marks was a supervising producer of medical programming for Ivanhoe Broadcast News. She is a Telly award winner and Freddie award finalist. When she’s not writing, she enjoys spending time with her husband and four children, traveling, and cheering on the UCF Knights.

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