Differential Diagnosis for Diarrhea of 2 Weeks Duration

Single Most Likely Diagnosis

• Viral Gastroenteritis: This is often the most common cause of acute diarrhea, which can sometimes persist for up to 2 weeks. Viruses such as norovirus, rotavirus, and adenovirus are common culprits.

Other Likely Diagnoses

• Bacterial Gastroenteritis: Bacteria like Salmonella, Shigella, and Campylobacter can cause diarrhea that lasts for weeks. The onset is often more sudden than viral causes.
• Irritable Bowel Syndrome (IBS): While IBS is a chronic condition, its symptoms can fluctuate, and some patients may experience prolonged periods of diarrhea.
• Food Intolerance: Lactose intolerance, fructose malabsorption, or other dietary intolerances can lead to chronic or recurrent diarrhea.
• Medication-Induced Diarrhea: Various medications, including antibiotics, antacids, and laxatives, can cause diarrhea as a side effect.

Do Not Miss Diagnoses

• Inflammatory Bowel Disease (IBD): Conditions like Crohn's disease and ulcerative colitis can present with chronic diarrhea and are critical to diagnose due to their potential for severe complications.
• Celiac Disease: An autoimmune reaction to gluten that can cause chronic diarrhea, malabsorption, and other systemic symptoms.
• Giardiasis: A parasitic infection that can cause prolonged diarrhea, especially in individuals who have traveled to endemic areas or have been exposed to contaminated water.
• Clostridioides difficile (C. diff) Infection: A bacterial infection that can cause severe, potentially life-threatening diarrhea, especially in patients who have recently used antibiotics.

Rare Diagnoses

• Microscopic Colitis: A condition characterized by inflammation of the colon that can cause chronic, watery diarrhea.
• Whipple's Disease: A rare, systemic bacterial infection that can cause diarrhea, among other symptoms like weight loss and joint pain.
• Tropical Sprue: A rare condition that affects the small intestine's ability to absorb nutrients, leading to chronic diarrhea, typically seen in individuals who have traveled to or live in tropical regions.
• HIV/AIDS: In its early stages, HIV infection can cause chronic diarrhea among other symptoms, due to the immune system's compromised state.