Reviewed by: HU Medical Review Board | Last Reviewed: January 2018.

Diarrhea is defined as loose, watery stool that occurs more than 3 times per day.1 Diarrhea that lasts for 4 weeks or more is considered chronic diarrhea.2

Diarrhea is a typical symptom of inflammatory bowel disease.3,4 The severity of diarrhea ranges from mild to severe. It may get worse when the disease flares up and better when inflammation goes down.4 If Crohn’s disease affects your small intestine, you may have mostly watery diarrhea.2,4 If your colon is affected with Crohn's disease or ulcerative colitis, your diarrhea may be bloody. You may experience urgency or incontinence, which is when you are unable to control your bowel movements.

Inflammation is the main cause of diarrhea in people with inflammatory bowel disease (IBD). When your intestine is inflamed, it absorbs much less sodium and water. It also may leak more fluids. The result is loose, watery stool. However, other factors contribute to diarrhea in people with IBD. These include:4

  • Difficulty absorbing fat, starches, sugars, and bile acids
  • Bacterial infection
  • Fistulas
  • Malabsorption after surgery

What other conditions can cause persistent diarrhea?

There are hundreds of causes of chronic diarrhea.2 Testing for all the causes is not practical. Your health care provider will ask you questions about the type of diarrhea you are having in order to narrow down the list of possible causes. Diarrhea can be classified as watery, fatty, or inflammatory (with blood or pus). Your provider will use this information and other clues from your medical history to decide what tests are needed.

How common is diarrhea?

About 3% to 5% of the population has chronic diarrhea from any cause.2 One study reported that 77% of people with ulcerative colitis and 82% of people with Crohn's disease had diarrhea at the time of their diagnosis.4 In a year-long survey of people with Crohn’s disease, a similar proportion (84%) reported having diarrhea during a flare.5 Another 13% reported having diarrhea even when their disease was in remission.

How is diarrhea evaluated?

To find the cause of diarrhea, your health care provider will take a medical history, perform a physical examination, and do laboratory tests.

You may be asked questions such as:2-4

  • When did the diarrhea start?
  • Would you describe it as watery or fatty?
  • Do you see blood or pus in the diarrhea?
  • How often do you have diarrhea?
  • Can you always control your bowel movements?
  • What makes the diarrhea worse? What makes it better?
  • Have you recently traveled? Taken medications? Changed your diet?
  • Do you have any food allergies?
  • What other symptoms do you have?
  • Has anyone in your family been diagnosed with an inflammatory bowel disease?

During the physical examination, your provider will look and listen to your abdomen. He or she will probably perform a rectal examination to look for signs of perianal disease, which suggests inflammatory bowel disease.2 If signs of perianal disease or rectal bleeding are found, you will probably need additional tests to confirm the diagnosis.

Your health care provider may ask you to provide stool samples.2 The samples may be analyzed for hidden blood in the stool, markers of inflammation, and electrolytes. One test for inflammation is the “fecal calprotectin test.”2 This test is a reliable way to screen for inflammatory bowel disease. You may need to have blood work to check for anemia and inflammation, among other things.

If laboratory tests suggest that you have inflammatory bowel disease, your provider will probably recommend a colonoscopy. An colonoscopy is performed using a long, thin tube with a very small camera and light. The camera lets your provider look inside your digestive tract for signs of inflammatory bowel disease.

How is diarrhea related to inflammatory bowel disease treated?

Most of the time, diarrhea related to IBD gets worse because inflammation has flared up.4 Therefore, treating the inflammation is the best way to manage the diarrhea. IBD is treated with:

Anti-diarrheal medications can help people with diarrhea after they have had surgery to remove part of the digestive tract.4 Some fiber supplements, called bulking agents, also may be useful. They bind to some of the water and make the stool a little firmer.4 It is important to note that these over-the-counter medications are meant for people without a severe digestive disorder, such as IBD. Therefore, talk with your health care provider before using any non-prescription products to manage your IBD symptoms. Over-the-counter medication could interact with other medications you are taking. Inflammation could change the way over-the-counter medications act.

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