Management of Diarrhea in Adults
For uncomplicated diarrhea, start loperamide 4 mg immediately, then 2 mg after each loose stool (maximum 16 mg/day), combined with oral rehydration and dietary modifications. 1, 2, 3
Initial Assessment: Classify as Uncomplicated vs Complicated
Uncomplicated diarrhea includes patients with mild to moderate symptoms (grade 1-2) without warning signs—these can be managed outpatient with conservative measures. 1, 4
Complicated diarrhea requires immediate hospitalization and includes patients with any of the following: 1, 5
- Fever, bloody stools, or severe cramping
- Signs of severe dehydration (tachycardia, orthostatic hypotension, urine output <0.5 mL/kg/h)
- Immunosuppression or neutropenia
- Persistent vomiting or diminished performance status
- Signs of sepsis (altered mental status, fever with tachycardia)
Management of Uncomplicated Diarrhea
Loperamide dosing: 4 mg initial dose, followed by 2 mg after every unformed stool or every 4 hours, not exceeding 16 mg daily. 1, 2, 3
Oral rehydration: Aggressive fluid replacement with oral rehydration solutions or commercial electrolyte solutions is essential to prevent dehydration. 1, 6, 4
- Eliminate lactose-containing products (except yogurt and firm cheeses)
- Avoid high-osmolar dietary supplements, spices, coffee, alcohol, and foods high in insoluble fiber
- Consider the BRAT diet (bananas, rice, applesauce, toast)
- Replace electrolytes, especially potassium
Monitoring: Instruct patients to record stool frequency and report warning signs (fever, dizziness on standing, blood in stool). 1
Skin protection: Use skin barriers to prevent irritation from fecal material, particularly in incontinent patients at risk for pressure ulcers. 1
Management of Complicated Diarrhea
Immediate hospitalization is required for intensive management. 1, 5
Fluid resuscitation: Start with IV bolus of 20 mL/kg if tachycardia or suspected sepsis is present, targeting adequate central venous pressure and urine output >0.5 mL/kg/h. 5
Laboratory evaluation: Obtain complete blood count with differential, electrolyte panel, renal function, and stool cultures for Clostridium difficile, Salmonella, E. coli, Campylobacter, and Shigella. 5, 4
Empiric antibiotics: Start broad-spectrum antibiotics immediately while awaiting culture results. Reasonable options include: 1, 5
- Piperacillin-tazobactam or imipenem-cilastatin as monotherapy
- Cefepime or ceftazidime plus metronidazole
- Fluoroquinolones with metronidazole
Loperamide: Can still be administered at standard dosing (4 mg initially, then 2 mg after each loose stool, maximum 16 mg/day) unless contraindicated. 1, 2
Second-line therapy: If diarrhea persists after 48 hours despite initial treatment, add octreotide 100-150 μg subcutaneously or IV three times daily, which can be escalated to 500 μg three times daily if needed. 1, 5, 6
Critical Contraindications to Loperamide
Absolutely avoid loperamide in: 6, 2
- Bloody diarrhea or suspected dysentery without antibiotic coverage
- Fever with suspected bacterial infection
- Suspected C. difficile infection
- Suspected Shiga toxin-producing E. coli
- Progressive abdominal distension
- Neutropenic patients (risk of aggravating ileus)
- Immunotherapy-induced grade 3-4 diarrhea
Special Considerations
Neutropenic enterocolitis: Requires broad-spectrum antibiotics covering gram-negative enteric organisms, gram-positives, and anaerobes. Avoid all anticholinergics, antidiarrheals, and opioids as they worsen ileus. Consider G-CSF therapy. 5, 2
Surgical consultation: Indicated for persistent GI bleeding after correcting coagulopathy, free intraperitoneal perforation, abscess formation, or clinical deterioration despite aggressive supportive measures. 5
Multidisciplinary approach: Patients with bloody diarrhea, neutropenia, or sepsis require evaluation by gastroenterology, infectious disease, and potentially critical care specialists. 5
When to Refer
Urgent gastroenterology referral is needed for: 7
- Red flag symptoms: bloody stools, unintentional weight loss, anemia, palpable abdominal mass
- Persistent symptoms beyond 4 weeks (chronic diarrhea)
- Failure to respond to initial management within 48 hours
Most cases of acute diarrhea are self-limited viral gastroenteritis and do not require diagnostic workup or specialist referral. 7, 4 Reserve extensive testing for high-risk patients with complicated presentations.