Please note: This information was current at the time of publication but now may be out of date. This handout provides a general overview and may not apply to everyone. 

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Am Fam Physician. 2011;84(10):1133-1134

See related article on chronic diarrhea.

What is chronic diarrhea?

It is frequent, loose bowel movements that last longer than four weeks.

What causes it?

It may be caused by an infection, a disease, bowel surgery, or certain medicines.

Irritable bowel syndrome (IBS) is a common cause of chronic diarrhea. IBS is an uncomfortable disorder, but it is not dangerous. It causes cramps, a change in bowel habits, and watery diarrhea (which can sometimes alternate with constipation) after meals. People with IBS usually feel better after having a bowel movement. With IBS, there may be mucus in the stool, but not blood. Stress and eating large or spicy meals may make IBS worse.

Inflammatory bowel disease (IBD) is a much more serious condition that causes chronic diarrhea. With IBD, there may be blood or pus in the stool. There are two types of IBD: ulcerative colitis and Crohn disease. Ulcerative colitis usually causes rectal bleeding, diarrhea, and pain during a bowel movement. It can also cause fever, weight loss, and anemia. Crohn disease causes diarrhea, stomach pain, and infections in the anal area.

Microscopic colitis is a diarrheal illness in older people. It causes diarrhea at night that may continue even without eating. Using anti-inflammatory pain medicines (e.g., ibuprofen) for a long time may cause microscopic colitis.

Problems absorbing nutrients (called malabsorption) is another cause of chronic diarrhea. Symptoms include bloating and pale or foul-smelling stools. Malabsorption can be caused by Giardia infection, lactose (a sugar found in milk) intolerance, and celiac disease (a disease caused by gluten intolerance). Gluten is a protein found in certain grains, primarily wheat. Examples of wheat-based foods that contain gluten include breads, cakes, cereals, pizza, and pastas.

Clostridium difficile infection can also cause chronic diarrhea, especially following antibiotic use or hospitalization. This infection is serious and is caused by antibiotic-resistant bacteria that take over the bowel.

Chronic infection and malignancy (cancer) are other causes of chronic diarrhea. Symptoms include weight loss and swollen glands.

What are some danger signs?

  • Blood in stools

  • Dehydration

  • Fever

  • More than three stools per day for several days

  • Stomach pain

  • Weakness

  • Weight loss

How is it diagnosed?

Your doctor will ask you about your allergies, diet, medicines you are taking, family history, surgical history, and travel before doing an examination. He or she may also do other tests, such as blood tests, stool tests, cultures, and anoscopy. If these tests do not tell your doctor the cause of your diarrhea, you may need a sigmoidscopy, colonoscopy, or colon biopsy.

There are no specific tests to diagnose IBS. Describing your symptoms can help with diagnosis, and blood tests are usually done to make sure nothing else is causing the diarrhea. To diagnose IBD, you will probably need blood tests and a colonoscopy. Other tests may be needed to diagnose microscopic colitis, malabsorption, and chronic infections.

How is it treated?

The type of treatment needed depends on the cause of the diarrhea. It is important to drink a lot of water to prevent dehydration. Antibiotics or laxatives can contribute to diarrhea, so it may help to stop taking them. Fasting (not eating food for a certain amount of time) may help some types of diarrhea, but not all.

Most conditions that cause diarrhea can be treated. Diarrhea caused by certain medicines and foods will usually go away without treatment.

Where can I get more information?

Your doctor

AAFP's Patient Education Resource

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