What is the management approach for an adult presenting with diarrhea?

Management of Diarrhea in Adults

For an adult presenting with diarrhea, immediately assess severity and warning signs, initiate oral rehydration for mild-to-moderate cases, and use loperamide (4 mg initial dose, then 2 mg every 2-4 hours, max 16 mg/day) for symptomatic relief in uncomplicated watery diarrhea. 1, 2, 3

Initial Assessment and Triage

Determine severity by evaluating for warning signs that require urgent medical attention 1:

• High fever, bloody stools, severe vomiting 1
• Signs of severe dehydration: altered mental status, tachycardia, poor skin turgor, dry mucous membranes 1
• Immunosuppression or significant systemic illness 1

Self-management is appropriate for otherwise healthy adults with uncomplicated acute watery diarrhea, but medical supervision is needed for frail elderly, immunocompromised patients, or those with chronic bowel disease. 1

Rehydration Strategy

Mild to Moderate Dehydration

Oral rehydration is the preferred first-line treatment. 1

• For otherwise healthy adults: glucose-containing drinks, electrolyte-rich soups, or diluted fruit juices with saltine crackers are sufficient 1, 2
• For elderly patients or grade 2+ diarrhea: use formal oral rehydration solutions (ORS) containing 65-70 mEq/L sodium and 75-90 mmol/L glucose 2
• Total fluid intake should be 2200-4000 mL/day, adjusted to exceed ongoing losses 2

Caution: Avoid overhydration in elderly patients with heart or kidney failure 2

Severe Dehydration (Grade 3-4)

Intravenous rehydration is mandatory. 2, 1

• Use isotonic saline or balanced salt solutions 2
• If tachycardic and potentially septic: give initial bolus of 20 mL/kg 2
• Continue rapid fluid replacement until clinical signs improve (blood pressure normalizes, urine output >0.5 mL/kg/h, mental status clears) 2
• Monitor central venous pressure and urinary output in severe cases 2

Dietary Management

Continue eating based on appetite—fasting provides no benefit. 1

• Resume age-appropriate usual diet during or immediately after rehydration 1, 4
• Avoid spices, coffee, alcohol, and reduce insoluble fiber 2, 4
• Consider avoiding milk and dairy products (except yogurt and firm cheeses) as this may reduce symptom intensity 2, 4
• Small, light meals are better tolerated than large, fatty, or heavy meals 1

Pharmacological Management

Loperamide (First-Line Antidiarrheal)

Loperamide is the drug of choice for acute watery diarrhea in adults. 1, 3

• Dosing: 4 mg initial dose, then 2 mg every 2-4 hours or after each unformed stool 2, 4
• Maximum: 16 mg/day 2, 4
• FDA-approved for acute nonspecific diarrhea and chronic diarrhea associated with inflammatory bowel disease 3

Contraindications—avoid loperamide in 1:

• Bloody diarrhea or suspected inflammatory diarrhea
• Fever with diarrhea
• Suspected or proven bacterial dysentery

Antiemetics

• Ondansetron facilitates tolerance of oral rehydration in patients with vomiting 1

Antibiotics

Empiric antibiotics are NOT routinely recommended for acute watery diarrhea. 1, 4

Consider antibiotics only for 1, 5:

• Moderate to severe traveler's diarrhea
• Fever with bloody stools (dysentery)
• Known bacterial pathogens requiring treatment (Shigella, Campylobacter)
• Preferred agent: Azithromycin 500 mg single dose for watery diarrhea; 1000 mg single dose for febrile diarrhea/dysentery 5

When to Seek Medical Attention

Refer or escalate care if 1:

• No improvement within 48 hours
• Worsening symptoms or overall condition
• Development of warning signs: severe vomiting, persistent fever, abdominal distension, blood in stools, signs of dehydration

Chronic Diarrhea (>3 Weeks Duration)

For diarrhea persisting beyond 14-21 days, diagnostic workup is necessary to identify underlying etiology. 4

• Continue rehydration and loperamide as above 4
• Empiric antimicrobials are NOT recommended without diagnostic testing 4
• Perform stool studies and consider gastroenterology referral, especially if red flag symptoms present (blood in stool, weight loss, anemia, palpable abdominal mass) 4, 6

Common Pitfalls to Avoid

• Do not routinely order stool cultures in uncomplicated acute diarrhea—reserve for severe illness, bloody stools, fever, immunosuppression, or suspected outbreak 1, 7
• Do not use loperamide with bloody diarrhea or fever—risk of worsening inflammatory or invasive bacterial infections 1
• Do not give empiric antibiotics for chronic diarrhea without appropriate diagnostic testing 4
• Monitor for paralytic ileus when using high-dose loperamide 2
• Avoid rapid fluid resuscitation in mild-to-moderate hypovolemia—match fluid administration rate to ongoing losses 2