What is the appropriate management for an otherwise healthy adult patient presenting with diarrhea?

Management of Acute Diarrhea in Otherwise Healthy Adults

For an otherwise healthy adult with acute uncomplicated diarrhea, start loperamide 4 mg immediately, then 2 mg after each unformed stool (maximum 16 mg daily), combined with adequate fluid intake guided by thirst. 1, 2

Initial Risk Stratification

Before initiating treatment, screen for warning signs that require hospitalization rather than outpatient management 1:

• High fever (>38.5°C)
• Frank blood in stools
• Severe vomiting preventing oral intake
• Clinical dehydration (tachycardia, orthostatic hypotension, decreased urine output <0.5 mL/kg/h)
• Age >75 years or frail elderly
• Immunosuppression (HIV, chemotherapy, chronic steroids, transplant recipients)
• Chronic inflammatory bowel disease

If any red flags are present, hospitalize immediately for IV fluid resuscitation and further evaluation 1, 3.

Outpatient Management for Uncomplicated Cases

Antidiarrheal Therapy

Loperamide is the first-line agent 1, 2:

• Initial dose: 4 mg orally
• Maintenance: 2 mg after each unformed stool
• Maximum: 16 mg per day
• Clinical improvement typically occurs within 48 hours 1

Critical safety warnings 2:

• Never exceed 16 mg daily due to risk of cardiac arrhythmias, QT prolongation, and sudden death
• Avoid in patients taking QT-prolonging drugs (antiarrhythmics, antipsychotics, certain antibiotics)
• Contraindicated if bloody diarrhea develops (risk of toxic megacolon)
• Stop immediately if constipation, abdominal distention, or ileus develops

Fluid Management

Maintain hydration using thirst as your guide 1:

• Glucose-containing drinks or electrolyte-rich soups are sufficient
• Oral rehydration solutions (ORS) are unnecessary for mild-moderate diarrhea in otherwise healthy adults
• Resume normal eating guided by appetite with small, light meals
• Avoid fatty, heavy, spicy foods and caffeine temporarily 1

Antibiotic Considerations

Do NOT prescribe empiric antibiotics for routine acute diarrhea in otherwise healthy adults 1:

• Most cases are viral and self-limited 4, 5, 6
• Antibiotics are reserved for proven specific pathogens, traveler's diarrhea, or high-risk populations
• Routine stool cultures are not recommended unless red flags are present 6

When to Escalate Care

Refer for diagnostic workup if 1, 4:

• Symptoms persist beyond 3 weeks (chronic diarrhea)
• Development of red flag symptoms during treatment
• No improvement after 48 hours of loperamide therapy
• Weight loss, anemia, or palpable abdominal mass develops

Common Pitfalls to Avoid

• Do not use loperamide if bloody diarrhea is present - this can precipitate toxic megacolon 2
• Do not exceed maximum daily loperamide dose - higher doses cause life-threatening cardiac arrhythmias 2
• Do not order stool cultures routinely - they are low-yield and expensive in uncomplicated cases 6
• Do not prescribe antibiotics empirically - this promotes resistance and is ineffective for viral causes 1, 5
• Do not recommend complex oral rehydration solutions - simple fluids guided by thirst are adequate for mild-moderate cases 1

The vast majority of acute diarrhea cases in healthy adults are self-limited viral illnesses requiring only symptomatic management 5, 7, 6. The key clinical skill is identifying the minority of patients who require hospitalization or further investigation based on red flag features 1, 4.