Complications of Gastroenteritis (Stomach Flu)

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. ( 1 ) What you might not know is this condition can sometimes trigger unusual complications — or secondary problems. Many of these issues will eventually go away, while others may linger.
Dehydration: A Common Risk? Dehydration Dehydration is the most common complication of gastroenteritis. (1) 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, the elderly, 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). Dehydration can lead to more serious problems, such as: Heat Injury If you don’t have enough fluids while you’re physically active, you could have a life-threatening heatstroke. Urinary and Kidney Issues A long or repeated episode of dehydration can trigger kidney stones, urinary tract infections (UTIs) , or kidney failure. Seizures When your electrolytes are out of whack, you could develop seizures. Hypovolemic Shock This life-threatening condition happens when low blood volume causes a drop in blood pressure and the amount of oxygen in your body. ( 2 ) You may be able to prevent dehydration by drinking extra fluids, and in some cases, taking an oral rehydration solution. (2)
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Gastroenteritis and Long-Term Stomach Problems Stomach Problems Most of the time, 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 you’ll have a decrease in the variety and quantity of good bacteria in your gut. ( 3 ) In one study, about 1 in 5 people who had norovirus, a common culprit for gastroenteritis, experienced changes in their microbiota. (3) Post-Infectious IBS One possible complication of gastroenteritis is something called post-infectious irritable bowel syndrome (IBS). This condition resembles IBS and causes symptoms such as diarrhea, nausea, stomach cramps, or constipation. ( 4 ) Studies have shown that post-infectious IBS affects between 5 and 32 percent of people who have gastroenteritis. (3) Symptoms can last months or even years. The good news is they usually do go away. (3) Colitis and Crohn’s Some people with gastroenteritis may develop an inflammatory bowel disease such as ulcerative colitis or Crohn’s disease — conditions that cause inflammation of your digestive tract. ( 5 , 6 ) Researchers believe an abnormal immune system reaction may be the trigger. When your immune system tries to fight off a virus or bacteria, it might also attack the cells in your digestive tract. (5) Another type of colitis, called hemorrhagic colitis, can happen when you have gastroenteritis caused by Escherichia coli ( E. coli ) bacteria. With this condition, E. coli infects the large intestine and produces a toxin that causes bloody diarrhea and other problems. ( 7 )
Gastroenteritis and Pregnancy Complications Pregnancy Problems As many as one-third of pregnant women will have gastroenteritis during their pregnancy. ( 8 ) While most pregnant women will recover from the sickness without any problems, it can lead to complications. Severe dehydration from the illness may prompt preterm labor. (8) In a 2017 study , gastroenteritis during pregnancy was also linked to miscarriages, low birth weight, and stillbirth. ( 9 ) It’s a good idea to see your doctor if you’re pregnant and have symptoms of gastroenteritis. If you do develop the stomach flu, be sure to drink plenty of liquids and get adequate rest.
Gastroenteritis and Aneurysms Aneurysms Having gastroenteritis may up your risk of developing an aortic aneurysm — a bulge in the wall of the major blood vessel that carries blood from your heart to the rest of your body. ( 10 ) In a 2008 Swedish study, researchers found a person’s risk of an aortic aneurysm was higher within three months after having a salmonella infection . ( 11 ) Aortic aneurysms may not cause any symptoms at first, but if they burst, they can be deadly. ( 12 )
Gastroenteritis and Reactive Arthritis Reactive Arthritis A bout of gastroenteritis can lead to reactive arthritis — a painful form of inflammatory arthritis. It used to be called Reiter’s syndrome. ( 13 ) Reactive arthritis can occur “in reaction” to an infection caused by salmonella, campylobacter, yersinia, shigella, E. coli , vibrio, or other bacteria. In a 2001 study, about 29 percent of people who had a salmonella infection developed symptoms of reactive arthritis. ( 14 ) Reactive arthritis may cause painful, red, and swollen joints, especially in the knees, ankles, and feet. Additionally, some people experience swelling of the membrane lining the eyes (conjunctivitis) or inflammation of the urinary tract. ( 15 ) Recovery for this type of arthritis varies from person to person. Some people get better after their first flare of symptoms. Symptoms usually last from 3 to 12 months. For about 30 to 50 percent of people, symptoms return or become chronic. (15)
What Should You Do if You Have Signs of a Complication? What to Do See your doctor if you think you have a complication associated with gastroenteritis. Your healthcare provider can monitor your condition to make sure it doesn’t worsen. There may also be a treatment option available, depending on the type of issue you have. It’s important to remember that most people with gastroenteritis will recover without experiencing any long-term problems. (3)