Diarrhea Classification and Management

Classification by Duration

Acute diarrhea lasts less than 14 days and is predominantly infectious in etiology, typically self-limiting within days to weeks, according to the American College of Gastroenterology 1
Persistent diarrhea continues for 14-29 days and warrants evaluation for parasitic infections, such as Cryptosporidium, Giardia, Cyclospora, Cystoisospora, and Entamoeba histolytica, as recommended by the Infectious Diseases Society of America 2, 1
Chronic diarrhea lasts 30 days or longer and requires comprehensive gastroenterological workup for non-infectious etiologies, as suggested by the American Gastroenterological Association 1

Acute watery diarrhea is most commonly caused by norovirus, presenting with vomiting and nonbloody diarrhea lasting 2-3 days, with low-grade fever in 40% during the first 24 hours, according to the Centers for Disease Control and Prevention 2, 3
Acute bloody diarrhea is defined by frequent scant stools with visible blood admixed in the commode and mucus, often with fever, and is classified as severe disease requiring immediate evaluation, as stated by the American College of Emergency Physicians 4, 1

Stool specimens should be tested in patients with fever and bloody or mucoid stools, or severe abdominal cramping or signs of dysentery, as recommended by the Infectious Diseases Society of America 2, 3
Immunocompromised patients should be tested for a broader panel of pathogens, including Cryptosporidium, Cyclospora, Cystoisospora, microsporidia, MAC, and CMV, as suggested by the American Society of Transplantation 2

Antibiotics are indicated only for moderate-to-severe bacterial diarrhea or dysentery, and provide no benefit for viral gastroenteritis, exposing patients to unnecessary harm, as stated by the American Academy of Pediatrics 3
Loperamide is FDA-approved for acute nonspecific diarrhea in patients ≥2 years of age, and for chronic diarrhea associated with inflammatory bowel disease, as approved by the FDA 3