What Causes Diarrhea After Eating?

Diarrhea after every meal may indicate a larger digestive issue.
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Nearly everyone experiences diarrhea from time to time, but diarrhea after every meal can be a sign of a larger problem. It may also take a bit of detective work to diagnose, as there are a number of possible causes of diarrhea after eating.


When Diarrhea After Eating Becomes an Issue

The Cleveland Clinic defines mild diarrhea as loose and watery bowel movements that may be accompanied by cramping, bloating, urgency, nausea and vomiting. The condition progresses to severe diarrhea if, in addition to those symptoms, you have undigested food, blood or mucus in your stool, experience weight loss or dehydration or have severe pain or fever.

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The primary symptom of viral gastroenteritis — commonly called stomach flu — is diarrhea that usually resolves within a few (miserable) days. In the case of food poisoning, diarrhea and other symptoms may last a couple of weeks.


But if diarrhea persists almost every time you eat, certain clues can help you and your doctor get to the root cause.

1. Digestive Diseases or Disorders

"The first thing I would wonder is if you have an underlying issue that has been undiagnosed," says Will Bulsiewicz, MD, a gastroenterologist with Lowcountry Gastroenterology in Mount Pleasant, South Carolina, and author of ​The Fiber Fueled Cookbook​.


Some possibilities, he says, include:

  • Celiac disease
  • An infection such as Clostridium difficile (C. diff.)
  • A parasitic infection such as Giardia
  • Inflammatory bowel disease (IBD)
  • Microscopic colitis

Symptoms of these conditions include blood in the stool, which can indicate an IBD such as ulcerative colitis or Crohn's disease, anemia or symptoms of anemia such as fatigue, lightheadedness, weakness and weight loss.


Diarrhea that disrupts sleep in the middle of the night is one sign of microscopic colitis, an autoimmune condition.

Chronic diarrhea may also affect people who have gallbladder problems or have had their gallbladder removed.

2. Gallbladder or Pancreas Issues

"That is not uncommon — about 10 percent of people who have had their gallbladder removed develop chronic diarrhea, or bile salt enteropathy," Dr. Bulsiewicz says, adding that "it's quite easy to treat once it's diagnosed."



In some people, the underlying problem may stem from pancreatic insufficiency, which impairs the absorption of fats in the small intestine.

3. Could It Be IBS?

Irritable bowel syndrome (IBS) is the most common cause of chronic diarrhea after eating. Though less debilitating than IBD or celiac disease, IBS can still have a serious negative impact on quality of life.


People with IBS may have what Dr. Bulsiewicz calls an overactive gastrocolic reflex.

"The entire gut is wired together — the stomach talks to the colon, the colon talks to the stomach," he explains. "When the stomach receives food, it sends a signal to the colon to start to move and make room."

Normally, this reflex triggers a healthy bowel movement after eating. But in someone with IBS, the reflex is over-stimulated, which leads to diarrhea after a meal.


4. Food Allergies and Intolerances

If the diarrhea follows a specific pattern — say, chronic but sporadic — that could indicate a food intolerance or food allergy.

According to Mayo Clinic, people with a food intolerance may be able to ingest small amounts of those foods without consequence, but a true food allergy will be set off by even the smallest amount of the food or food component in question.


While fish, shellfish, peanuts and tree nuts cause most of the food allergies in adults, the foods most likely to trigger diarrhea are dairy, which can be especially difficult for people with an intolerance to lactose, fructose or artificial sweeteners.

When to See a Doctor About Diarrhea After Eating

The Cleveland Clinic recommends getting medical attention if you have severe diarrhea, especially with a fever lasting more than 24 hours, or if you're unable to drink or retain fluids because of vomiting.

"You should definitely see a doctor if you have any of those red-flag symptoms," Dr. Bulsiewicz says. "But I would add that any person whose diarrhea is affecting their quality of life has enough reason to see a doctor."




Is this an emergency? If you are experiencing serious medical symptoms, please see the National Library of Medicine’s list of signs you need emergency medical attention or call 911.

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