Chronic Diarrhea

Definition:  Diarrhea, continuous for >1 month, or recurrent episodes that come & go. As opposed to Acute Diarrhea, the chronic form is never caused by a Virus. Viruses just don’t last that long.

The following is the clinicianโ€™s condensed thought-process when face-to-face with a patient. For more in-depth discussion and explanations, see Chronic Diarrhea — Full Text.

Causes of Chronic Diarrhea

xxSuspect / Diagnose by General Clinician
โ€ข Irritable Bowel Syndrome (IBS)
โ€ข Inflammatory Bowel Disease (IBD)
โ€ข Celiac Disease
โ€ข Bacteria / Parasites
โ€ข Malabsorption Syndromes
โ€ข Post-Cholecystectomy Surgery (gallbladder)
Lactose Intolerance
โ€ข Colon Cancer
โ€ข Medications, Laxative Abuse
โ€ข HIV
โ€ข Hyperthyroidism
xxxxLet Gastroenterologist Consider It

โ€ข Chronic Pancreatitis
โ€ข Chronic Diverticulitis
โ€ข Diabetic Autonomic Neuropathy
โ€ข Adrenal Insufficiency (Addisonโ€™s Disease)
โ€ข Carcinoid tumors, Mastocytosis, & other xx xxxxVery Rare Diseases and Infections


1.  Probably diagnose Irritable Bowel Syndrome (IBS) or Lactose Intolerance

  • Far and away the most common causes
  • See below at the end for treatment suggestions
  • Note difference between Irritable Bowel Syndrome (IBS) & Inflammatory Bowel Disease (IBD)

2.  Before making above diagnoses: Order Basic Laboratory Tests:

2a.  Initial Tests

2b.  Possible Tests (they usually turn out negative)

  • Stool Culture for various Bacteriaย  —ย  Especially for immunocompromised persons
  • Stool Ova & Parasites for various Parasitesย  —ย  Only order for Men-having-Sex-with-Men; or for Persons Lived / Traveled in poor countries (must order at least 3 separate specimens)
  • Stool for C. difficile —ย  Suspect C. Difficile (see “bacteria” in link) if antibiotic use before diarrhea began; if recent hospitalization; also in immunocompromised patients
  • Fecal Fat (maybe)ย  —ย  If frequent greasy, foul-smelling stools, for Malabsorption

3. If tests abnormal, we Diagnose & Treat; some we refer for Colonoscopy:

  • Possible IBD (elevated Fecal Calprotectin &/or Fecal Lactoferrin; Sedimentation Rate / CRP)
  • Possible Celiac Disease (elevated tTG-IgA Antibody)
  • Possible Colon Cancer (low Hemoglobin on CBC suggesting Iron-Deficiency Anemia)

4.   If tests all normal  >>> seek “Red Flags“:

Diseases in bold require Gastroenterology Referral for diagnosis or confirmation.  They include:

  • Weight Lossโ€ฆโ€ฆโ€ฆโ€ฆโ€ฆ..โ€ฆโ€ฆ..โ€ฆ…………….โ€ฆ…could be one of many serious illnesses
  • Bloody Diarrheaโ€ฆโ€ฆโ€ฆโ€ฆ..โ€ฆโ€ฆ…………..โ€ฆโ€ฆโ€ฆ.maybe IBD, Colon Cancer, Amebic dysentery
  • Severe Diarrhea, esp. if also at nightโ€ฆ……..โ€ฆneeds colonoscopy
  • Significant abdominal pain alsoโ€ฆ……..โ€ฆโ€ฆ…We order CT Scan for Tumors outside the Lumen
  • Age >50 (at onset)โ€ฆโ€ฆ..โ€ฆโ€ฆโ€ฆ…….โ€ฆ…….โ€ฆ….age for Colon Cancer
  • Greasy, Malodorous Stoolsโ€ฆ……โ€ฆ…….โ€ฆโ€ฆ….Malabsorption
  • AIDS (advanced; not just HIV)โ€ฆโ€ฆ…..โ€ฆโ€ฆ..โ€ฆ. AIDS Infection (mainly for Cytomegalovirus)
  • Family History (IBD, Colon Cancer)……………..IBD, Cancer (by colonoscopy)
  • Immunocompromisedโ€ฆโ€ฆโ€ฆโ€ฆ……………โ€ฆโ€ฆ..Needs extensive work-up

5.  Tests All Normal & NO Red Flags >>>   Diagnose Irritable Bowel Syndrome (IBS)

  • See IBS link above for Diagnostic Criteria for IBS with Diarrhea
  • Try Treatment: More fiber in diet; psyllium (Metamucilยฎ); loperamide (Imodiumยฎ)
  • Consider avoiding dairy products if possible Lactose Intolerance
  • If no improvement:ย  Refer to Gastroenterologist to rule out rare diseases

See Chronic Diarrhea โ€” Full Text for more in-depth explanations and discussions.

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