What tests and treatment should be ordered for a patient presenting with diarrhea in urgent care?

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Last updated: July 1, 2025View editorial policy

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From the Guidelines

For a patient presenting with diarrhea in urgent care, the initial evaluation should include a thorough history, physical examination, and targeted laboratory tests, with a focus on oral rehydration and symptomatic management for mild to moderate cases. The most recent and highest quality study 1 provides guidelines for the diagnosis and management of infectious diarrhea, emphasizing the importance of stool testing for certain pathogens in specific circumstances. Key considerations include:

  • Complete blood count, basic metabolic panel, and stool studies (including culture, ova and parasites, and Clostridioides difficile testing if indicated) as basic tests.
  • Oral rehydration with electrolyte solutions and symptomatic management for mild to moderate cases without signs of severe dehydration or systemic illness.
  • Loperamide (2mg after each loose stool, maximum 8mg/day) or Bismuth subsalicylate (524mg every 30-60 minutes, maximum 8 doses/day) for non-bloody diarrhea without fever.
  • Antibiotics (such as Ciprofloxacin or azithromycin) may be indicated for specific bacterial causes or severe presentations.
  • Patients should maintain hydration, temporarily avoid dairy products and high-fiber foods, and follow up if symptoms worsen or persist beyond 3-4 days.
  • Severe cases with signs of dehydration, bloody diarrhea, high fever, or immunocompromised status may require intravenous fluids and hospital admission, as suggested by 1 and 1. It's also important to consider the mode of spread of diarrheal diseases and educate patients on careful hand hygiene, particularly if they are involved in food preparation, child or adult education, or healthcare, as noted in 1.

From the FDA Drug Label

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From the Research

Diagnostic Tests for Diarrhea

When a patient presents with diarrhea in urgent care, the following tests can be considered:

  • Stool culture: However, according to 2, stool culture orders should be reduced, especially for nosocomial diarrhea, as they are often low-yield.
  • Stool ova and parasites (O&P): Similar to stool cultures, 2 suggests reducing O&P orders for nosocomial diarrhea.
  • Clostridium difficile (C. difficile) toxin test: This test is recommended for patients with clinically significant diarrhea, especially if they have been exposed to antibiotics 3, 4.
  • Endoscopy: This can be used to diagnose pseudomembranous colitis, but it is expensive and invasive 3.
  • Enzyme immunoassay (EIA) for toxins A/B: This test is not recommended as a stand-alone assay due to its low sensitivity 4.
  • Molecular tests: These are recommended for the diagnosis of C. difficile infection (CDI) in patients with clinically significant diarrhea 4.

Treatment Considerations

When treating a patient with diarrhea, the following should be considered:

  • Antibiotic use: Certain antibiotics, such as clindamycin, cephalosporins, and penicillins, can increase the risk of C. difficile infection 3.
  • Azithromycin: While generally considered safe, azithromycin can increase the risk of C. difficile infection, especially with repeated courses 5.
  • Metronidazole or vancomycin: These antibiotics are effective in treating symptomatic C. difficile infection 3.
  • Infection control measures: Hand hygiene, isolation, and environmental disinfection can help prevent the spread of C. difficile 3.

Evaluation of Chronic Diarrhea

For patients with chronic diarrhea, the following tests can be considered:

  • Complete blood count
  • C-reactive protein
  • Anti-tissue transglutaminase immunoglobulin A (IgA)
  • Total IgA
  • Basic metabolic panel
  • Stool studies to categorize diarrhea as watery, fatty, or inflammatory 6.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Clostridium difficile-associated diarrhea and colitis.

Infection control and hospital epidemiology, 1995

Research

Laboratory diagnosis of Clostridium difficile infections: there is light at the end of the colon.

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America, 2013

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.

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