Chronic Diarrhea: Diagnosis and Management

Lawrence R. Schiller; Darrell S. Pardi; Joseph H. Sellin


Clin Gastroenterol Hepatol. 2017;15(2):182-193. 

In This Article

Abstract and Introduction


Chronic diarrhea is a common problem affecting up to 5% of the population at a given time. Patients vary in their definition of diarrhea, citing loose stool consistency, increased frequency, urgency of bowel movements, or incontinence as key symptoms. Physicians have used increased frequency of defecation or increased stool weight as major criteria and distinguish acute diarrhea, often due to self-limited, acute infections, from chronic diarrhea, which has a broader differential diagnosis, by duration of symptoms; 4 weeks is a frequently used cutoff. Symptom clusters and settings can be used to assess the likelihood of particular causes of diarrhea. Irritable bowel syndrome can be distinguished from some other causes of chronic diarrhea by the presence of pain that peaks before defecation, is relieved by defecation, and is associated with changes in stool form or frequency (Rome criteria).

Patients with chronic diarrhea usually need some evaluation, but history and physical examination may be sufficient to direct therapy in some. For example, diet, medications, and surgery or radiation therapy can be important causes of chronic diarrhea that can be suspected on the basis of history alone. Testing is indicated when alarm features are present, when there is no obvious cause evident, or the differential diagnosis needs further delineation. Testing of blood and stool, endoscopy, imaging studies, histology, and physiological testing all have roles to play but are not all needed in every patient. Categorizing patients after limited testing may allow more directed testing and more rapid diagnosis.

Empiric antidiarrheal therapy can be used to mitigate symptoms in most patients for whom a specific treatment is not available.


This clinical perspective addresses the definition, pathogenesis, diagnosis, and treatment of chronic diarrhea, which is based on a systematic review produced for the World Congress of Gastroenterology in 2013[1] and updated by the authors in 2016. Fifteen clinical questions are posed, followed by 24 recommendations pertinent to those questions with supporting evidence. In many instances there is not high-quality evidence to support the recommendations, and that is noted.

A search of PubMed for the years from 1975 to 2015 was conducted by using the following major search terms and subheadings including "diarrhea," "stool analysis," "irritable bowel syndrome," "chronic diarrhea AND diagnosis," "chronic diarrhea AND therapy," and "breath tests." Systematic reviews and meta-analyses were given priority for each topic when available, followed by clinical trial evidence.

The GRADE system was used to evaluate the strength of the recommendations and the overall quality of evidence.[2] A recommendation was graded as "strong" when the desirable effects of an intervention clearly outweigh the undesirable effects and as "conditional" when there is uncertainty about the tradeoffs. The quality of evidence ranged from "high" (implying that further research is unlikely to change the authors' confidence in the conclusion or in the estimate of the effect) to "moderate" (further research is unlikely to have an effect on the conclusion but might have an impact on the estimate of effect) or "low" (further research would be expected to have an important impact on the estimate of the effect or might change the conclusion altogether). For each recommendation, strength is abbreviated as "1" (strong) or "2" (conditional) and quality of evidence as "a" (high), "b" (moderate), or "c" (low).