Duration Defining Chronic Diarrhea
Diarrhea is considered chronic when symptoms persist for more than 4 weeks. 1
Consensus Definition Across Guidelines
The 4-week threshold is universally accepted across major gastroenterology societies and represents the point at which symptoms suggest a non-infectious etiology requiring further investigation 1:
The British Society of Gastroenterology (2018) explicitly states that "symptoms persisting for longer than 4 weeks suggest a non-infectious aetiology and merit further investigation" 1
The earlier BSG guidelines (2003) confirm this same timeframe, noting that "most groups would accept that symptoms persisting for longer than four weeks suggest a non-infectious aetiology" 1
Multiple international guidelines consistently use the ≥4 week duration as the defining criterion for chronic versus acute diarrhea 2, 3, 4
Clinical Significance of the 4-Week Cutoff
This temporal distinction is clinically meaningful because it fundamentally changes the diagnostic approach 1:
Acute diarrhea (<4 weeks) is predominantly infectious in origin, with management focused on preventing dehydration and electrolyte disturbances 5
Chronic diarrhea (≥4 weeks) requires systematic investigation for non-infectious causes including inflammatory bowel disease, microscopic colitis, celiac disease, bile acid diarrhea, malabsorption syndromes, and colorectal neoplasia 1, 2, 4
Practical Application
Once the 4-week threshold is crossed, the diagnostic workup should begin with first-line investigations in primary care, including complete blood count, inflammatory markers, celiac serology, thyroid function, and fecal calprotectin 3, 4. The presence of alarm features (weight loss, blood in stool, nocturnal symptoms, age >45-50 years) mandates more urgent and aggressive evaluation including colonoscopy with biopsies 2, 3.