SynopsisCodesLook ForDiagnostic PearlsDifferential Diagnosis & PitfallsBest TestsManagement PearlsTherapyReferences

View all Images (3)

Other Resources UpToDate PubMed


Contributors: Sreeja Natesan MD, Sarah K. Kennedy MD, Sara Manning MD
Other Resources UpToDate PubMed


Emergent Care / Stabilization:
In the setting of severe dehydration or hypovolemic shock, rapid intravenous (IV) access is needed to begin resuscitation. An IV fluid bolus (20-30 mL/kg of isotonic fluid such as Lactated Ringer's or normal saline) should be started. If sepsis is a concern, blood cultures and empiric antibiotics may be considered. Serial vital signs and examinations can help aid in resuscitation, including capillary refill, tenting of the skin, urine output, and mental status. If a patient is febrile or has abdominal pain or a concerning abdominal examination, advanced imaging is recommended.

Diagnosis Overview:
Diarrhea is defined as stool that contains excessive water content with either a larger-than-normal frequency or a less-solid-than-normal consistency. Typically, there are more than 3 stools per day or a total weight of over 200 grams a day.

Etiology / pathophysiology: The 4 common mechanisms leading to diarrhea include abnormal motility, decreased absorption of water, higher-than-normal osmotic load within the intestines, or increased secretion of fluids, resulting in loose stools. Diarrhea can also be categorized as infectious (viral, bacterial [eg, diarrheagenic Escherichia coli], and parasitic [eg, giardiasis]) or noninfectious (eg, functional disorder, malabsorptive diseases, foods, inflammatory bowel disease [Crohn disease, ulcerative colitis], irritable bowel syndrome, medication effects, cystic fibrosis, short gut syndrome, gastrointestinal [GI] bleeds, and toddler diarrhea).

Diarrhea is also characterized by duration, with acute diarrhea typically lasting less than 2 weeks, persistent diarrhea lasting 2-4 weeks, and chronic diarrhea lasting for more than a month. Most infectious diarrhea is short lived with a seasonal predominance in the winter in the United States. Norovirus and rotavirus are 2 of the most common viral pathogens, while foodborne infections account for the majority of bacterial disease. Traveler's diarrhea is frequently bacterial in nature, typically Escherichia coli. Chronic diarrhea is most commonly noninfectious.

Demographics: People of all ages are at risk of developing diarrhea, but those at the extremes of age or who are immunosuppressed can have the most severe symptoms and complications. Worldwide, 88% of deaths from diarrhea are due to lack of access to sanitary water or poor hygiene.

Predisposing history / risk factors: Diarrhea impacts certain patient populations more adversely than others due to the resulting severe dehydration and electrolyte abnormalities. These vulnerable populations include the young, older adults, and those who are immunocompromised, including patients on chronic steroids, those with diabetes, patients on immunosuppressants, and those undergoing cancer treatments such as chemotherapy. Outbreaks can occur where a large mass of people gather, including nursing homes, cruise ships, prisons, and day care settings. Milk and food intolerances or allergies can also lead to diarrhea, and a trial of avoidance can serve as a tool to determine etiology (eg, dairy-free milk or lactose-free foods, avoiding gluten). Toddler diarrhea typically occurs in children younger than 5 years and is frequently caused by the overconsumption of fruit juices, which contain a high load of carbohydrates and sugars.

Risk factors / exposures that can predispose to diarrheal illness include:
  • Age (very young children or older adults).
  • Close living quarters (dorms, cruise ships, nursing homes, prisons, shelters).
  • Comorbidities such as cirrhosis, HIV, obesity, inflammatory bowel disease.
  • Contaminated food.
  • Exposure to sick contacts.
  • Exposure to untreated water sources.
  • Immunosuppression.
  • Malignancy.
  • New medications or recent medication changes.
  • Recent antibiotic use.
  • Recent dietary changes.
  • Recent hospitalization.
  • Recent travel.


R19.7 – Diarrhea, unspecified

128333008 – Diarrheal disorder

Look For

Subscription Required

Diagnostic Pearls

Subscription Required

Differential Diagnosis & Pitfalls

To perform a comparison, select diagnoses from the classic differential

Subscription Required

Best Tests

Subscription Required

Management Pearls

Subscription Required


Subscription Required


Subscription Required

Last Reviewed:02/27/2024
Last Updated:04/01/2024
Copyright © 2024 VisualDx®. All rights reserved.
A medical illustration showing key findings of Diarrhea (Dehydration - Child/Adult)
Copyright © 2024 VisualDx®. All rights reserved.