Diarrhea in Adults - Infectious Disease Summary

Last updated: 30 January 2026

Overview

Diarrhea is the change in normal bowel movements characterized by an increase in frequency, water content, or volume of stools, as stated in the Introduction section.

The estimated yearly cases of diarrhea are at 1.5 billion worldwide. A detailed discussion about the prevalence of diarrhea is in the Epidemiology section.

Discussions on non-infectious and infectious causes of diarrhea are in the Etiology section.

The Pathophysiology section states that inflammatory diarrhea (ie watery or bloody diarrhea) is characterized by enterocyte damage, villus atrophy, and crypt hyperplasia. The development process of diarrhea in infected patients is in this section.

The Risk Factors section discusses different causes of diarrhea depending on factors such as the place of residence, history of travel, attendance in daycare, or ingestion of unsafe foods.

The Classification section defines the different types of diarrheas depending on the duration, causes, and symptoms. Classifications of acute traveler’s diarrhea are also listed in this section.



Diarrhea in Adults - Infectious_Disease SummaryDiarrhea in Adults - Infectious_Disease Summary

History and Physical Examination

The Clinical Presentation section describes the importance of an initial clinical evaluation in the diagnosis of diarrhea. The different clinical features of patients with different degrees of dehydration are also explained in this section.

The History section emphasizes the need to determine the onset of bowel movements, stool characteristics, and symptoms of volume depletion in the evaluation of diarrhea.

Evaluation of hydration status, vital signs, and signs of volume depletion should be the focus of the physical exam and are discussed in detail in the Physical Examination section.  

The Screening section identifies conditions that should be considered in patients presenting with acute diarrhea.

Diagnosis

Discussions on stool exams and microscopy, molecular diagnostic tests, stool culture and sensitivity, blood cultures, biopsy, and other tests that can be requested in the evaluation of diarrhea are in the Laboratory Tests and Ancillaries section.  

Other conditions that should be ruled out in the diagnosis of diarrhea are listed in the Differential Diagnosis section.

Management

A comprehensive discussion of the clinical manifestations of infectious diarrhea, which may aid clinical decision-making in its management, is provided in the Evaluation section. Indications for specialist consultation or hospitalization are also in this section.

General therapy principles for the management of infectious diarrhea are in the Principles of Therapy section.

The Pharmacological Therapy section discusses in detail the symptomatic therapy and pathogen-specific antibiotic treatment of infectious diarrhea as well as the duration of the therapy.

The Nonpharmacological section enumerates and discusses the importance of oral rehydration therapy and intravenous (IV) therapy in the management of diarrhea. 

The Prevention section includes measures to prevent diarrheal diseases and how to educate patients on these measures.

The Monitoring section identifies indications for follow-up in patients who were treated for infectious diarrhea.