Chronic Diarrhea
Chronic diarrhea is loose or watery stools lasting more than 4 weeks, evaluated per the 2019 AGA Clinical Practice Guideline on laboratory evaluation.
Symptoms
Loose or watery stools occurring frequently for more than 4 weeks; over 90% of chronic diarrhea has a noninfectious cause.
Causes and risk
Common causes include IBS-D, food intolerances, inflammatory bowel disease, bile acid diarrhea, celiac disease, and microscopic colitis, per the 2026 JAMA review.
How it is evaluated
Targeted testing -- fecal calprotectin or lactoferrin, celiac serology (with a total IgA level), and Giardia testing -- is recommended over broad, unfocused workups, per the AGA guideline, which also advises against routine ESR/CRP or stool ova-and-parasite testing.
Treatment
Treatment targets the underlying cause once identified; empiric anti-diarrheal medication should be avoided if there are bloody stools or fever, since these can signal an infection that needs different management.
When to seek care
Bloody stools, fever, nighttime diarrhea that wakes you from sleep, unintended weight loss, onset after age 45, or iron-deficiency anemia are alarm features warranting prompt evaluation, per current clinical review guidance. Diarrhea starting after a course of antibiotics should be tested for C. difficile.