What is the recommended treatment for an adult patient with acute diarrhea?

Treatment for Acute Diarrhea in Adults

For most adults with acute watery diarrhea, oral rehydration is the cornerstone of treatment, empiric antibiotics are not recommended, and loperamide can be used for symptom relief once adequate hydration is achieved. 1

Initial Assessment and Risk Stratification

Determine severity by evaluating for warning signs that require immediate medical attention 2:

• High fever (>38.5°C) suggests invasive/inflammatory process 3
• Bloody or mucoid stools indicate possible bacterial dysentery 1
• Severe vomiting preventing oral intake leads to rapid dehydration 1, 3
• Signs of dehydration: altered mental status, poor skin turgor, dry mucous membranes, orthostatic changes 2
• Immunocompromised status or significant comorbidities 1

Most cases are viral, self-limited, and require only supportive care without diagnostic workup 4, 5.

Rehydration Strategy

Mild to Moderate Dehydration

Oral rehydration solution (ORS) is first-line therapy for all patients who can tolerate oral intake 1:

• Reduced osmolarity ORS is recommended, though formal ORS is not essential for otherwise healthy adults 1, 2
• Acceptable alternatives include glucose-containing drinks (lemonades, sweet sodas, fruit juices) or electrolyte-rich soups 1, 3
• Maintain fluid intake as indicated by thirst 1, 2
• For patients with vomiting, administer small volumes (5-10 mL) every 1-2 minutes via spoon or syringe, gradually increasing 3

Severe Dehydration

Isotonic intravenous fluids (lactated Ringer's or normal saline) are required for 1:

• Severe dehydration with shock or absent peripheral pulse 2, 3
• Altered mental status 1
• Failure of oral rehydration therapy 1
• Ileus 1

Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS for remaining deficit 1.

Dietary Management

Resume normal, age-appropriate diet immediately after rehydration is completed 1:

• Food intake should be guided by appetite—there is no evidence that fasting benefits recovery 1, 2
• Small, light meals are appropriate 1, 3
• Avoid fatty, heavy, spicy foods and caffeine (including cola drinks) 1, 3
• Consider avoiding lactose-containing foods (except yogurt and firm cheeses) if diarrhea persists beyond several days 2, 3
• Continue breastfeeding throughout the illness in infants 1

Pharmacological Management

Antimotility Agents

Loperamide 2 mg is the drug of choice for immunocompetent adults with acute watery diarrhea 1, 6:

• Use flexible dosing according to loose bowel movements 1
• The outdated belief that loperamide "traps toxins" and prolongs illness is not evidence-based; modern evidence shows it safely relieves symptoms 2
• Contraindications: Do NOT use in children <18 years, bloody diarrhea, high fever (>38.5°C), or suspected inflammatory/invasive diarrhea 1, 3

Antiemetics

Ondansetron and other antiemetic agents can facilitate tolerance of oral rehydration in patients with vomiting 2.

Antibiotics

Empiric antimicrobial therapy is NOT recommended for most adults with acute watery diarrhea without recent international travel 1:

• Exceptions include immunocompromised patients or those appearing severely ill 1
• Antibiotics ARE indicated for:
  • Documented dysentery (high fever >38.5°C AND frank blood in stool) 3
  • Suspected enteric fever with sepsis 1
  • Moderate to severe traveler's diarrhea 1, 2
• Fluoroquinolones are first-line for empirical treatment of invasive diarrhea 3
• AVOID antibiotics in STEC O157 and other Shiga toxin 2-producing E. coli, as they increase risk of hemolytic uremic syndrome 1

Modify or discontinue antibiotics when a clinically plausible organism is identified 1.

When to Seek Medical Attention

Patients should seek immediate medical evaluation if 1, 2:

• No improvement within 48 hours 1, 2
• Worsening symptoms or overall condition 1, 2
• Development of bloody stools 2
• Persistent fever >38.5°C 2
• Severe vomiting or signs of dehydration 1, 2
• Abdominal distension 1, 2
• Altered mental status or severe lethargy 3

Special Populations

Elderly patients (>75 years) or those with significant comorbidities should be treated under physician supervision due to higher complication risk 3.

Asymptomatic contacts should NOT receive empiric or preventive therapy, but should follow appropriate infection prevention and control measures including hand hygiene 1.