Please note: This information was current at the time of publication but now may be out of date.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. 2020;101(8):online

Related article: Chronic Diarrhea in Adults: Evaluation and Differential Diagnosis

What is chronic diarrhea?

It is frequent, loose bowel movements lasting longer than one month.

What causes it?

It may be caused by some medicines, diseases, infections, or surgeries.

Irritable bowel syndrome (IBS) and functional diarrhea are common causes of chronic diarrhea. People with IBS have belly pain that gets better or worse with bowel movements. People with functional diarrhea have watery stools that get better with fasting (i.e., not eating food for a certain amount of time) and during sleep. There might be mucus in the stools, but not blood. IBS and functional diarrhea can be uncomfortable but are not dangerous.

Inflammatory bowel disease (IBD) also causes chronic diarrhea. There are two types: Crohn disease and ulcerative colitis. The stools often have blood or pus in them. IBD can cause belly pain, fever, weight loss, and anemia. People with IBD sometimes have symptoms that seem unrelated to their diarrhea. IBD is a serious condition that must be treated.

Microscopic colitis causes loose stools, even overnight and during fasting. It usually happens in older people and may be caused by using anti-inflammatory pain medicines (e.g., ibuprofen) for a long time.

Some people have diarrhea because of problems with certain foods. People with lactose intolerance have diarrhea when they eat or drink milk products. People with celiac disease have diarrhea when they eat foods containing gluten, a protein found in wheat and some other grains.

Most infections only cause diarrhea for a few days and go away without treatment. Clostridioides difficile can cause serious illness, usually after antibiotic use or a hospital stay. Some parasites, like Giardia, cause chronic diarrhea, usually after drinking contaminated water or eating tainted food.

What are some danger signs?

  • Blood in stools

  • Feeling dizzy when you stand up

  • Fever

  • Four or more stools per day for several days

  • Not urinating as much as usual

  • Severe belly 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 exam. The doctor will probably inspect your anus. He or she may also do blood tests and stool tests. If these tests do not tell your doctor the cause of your diarrhea, you may need a procedure called a sigmoidoscopy or colonoscopy to look at the inside of your large intestine.

How is it treated?

The type of treatment depends on the cause of the diarrhea. It is important to drink enough water to prevent dehydration. Talk to your doctor before you make major dietary changes or stop taking any of your prescription medicines.

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

Where can I get more information?

Your doctor

AAFP's Patient Information Resource

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