What is the management approach for acute gastroenteritis in adults?

Management of Acute Gastroenteritis in Adults

For uncomplicated acute gastroenteritis in adults, initiate oral rehydration with glucose-containing fluids or electrolyte-rich soups, use loperamide 2 mg flexibly dosed for symptom control once adequately hydrated, and resume normal diet guided by appetite—oral rehydration solutions are not necessary in otherwise healthy adults. 1, 2

Initial Assessment and Risk Stratification

Determine if self-management is appropriate or if medical supervision is required:

• Self-medication is safe for previously healthy adults under 75 years with sudden onset of loose/watery stools without warning signs 1
• Immediate medical evaluation is required for: high fever >38.5°C with frank blood in stools (dysentery), severe vomiting risking rapid dehydration, or obvious clinical dehydration 1
• Frail or elderly patients >75 years and those with significant systemic illnesses require physician-directed treatment 1

Rehydration Strategy

Oral rehydration is first-line for mild to moderate dehydration:

• Maintain adequate fluid intake guided by thirst using glucose-containing drinks (lemonades, sweet sodas, fruit juices) or electrolyte-rich soups 1, 2
• Oral rehydration solutions (ORS) are not needed in otherwise healthy adults—there is no evidence they relieve symptoms or shorten illness duration compared to standard fluids 1
• Low-osmolarity ORS formulations are preferred over sports drinks if ORS is used 2
• For moderate dehydration (6-9% deficit), administer 100 mL/kg over 2-4 hours if using ORS 2

Intravenous rehydration is reserved for:

• Severe dehydration, shock, altered mental status, failure of oral rehydration, or ileus 2
• Use isotonic fluids (lactated Ringer's or normal saline) until pulse, perfusion, and mental status normalize, then transition to oral fluids 2

Nutritional Management

Resume normal eating without dietary restrictions:

• Consumption of solid food should be guided by appetite—there is no evidence that solid food hastens or retards recovery in adults 1
• Small light meals are appropriate; avoid fatty, heavy, spicy foods and caffeine (including cola drinks) 1
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice) as they can exacerbate diarrhea through osmotic effects 2
• Consider avoiding lactose-containing foods (milk) in more prolonged episodes 1
• Early refeeding is recommended rather than fasting or restrictive diets 2

Pharmacological Management

Loperamide is the drug of choice for symptom control:

• Use loperamide 2 mg with flexible dosing according to loose bowel movements once the patient is adequately hydrated 1, 2
• Evidence suggests anti-diarrheal medication may diminish diarrhea and shorten its duration—there is no evidence that reducing stool output prolongs the disorder 1
• Do not use loperamide in cases of bloody diarrhea or high fever 2, 3

Antiemetics have limited but specific roles:

• Ondansetron may be given to adults after adequate hydration is achieved to facilitate oral rehydration when vomiting is significant 2, 3
• Avoid ondansetron in suspected inflammatory diarrhea or diarrhea with fever 3

Antimicrobials are rarely indicated:

• Viral agents are the predominant cause; antimicrobial therapy should be considered only for bloody diarrhea, recent antibiotic use, exposure to certain pathogens, recent foreign travel, or immunodeficiency 2
• Quinolones are first-line for empirical treatment of moderate to severe traveler's diarrhea with fever and/or bloody stools 1
• For C. difficile-associated diarrhea: oral vancomycin 125 mg four times daily for 10 days is indicated 4

Agents to avoid:

• Antimotility agents, adsorbents, antisecretory drugs, and toxin binders do not demonstrate effectiveness in reducing diarrhea volume or duration 2
• Probiotics are not widely available and available evidence does not support their use in early treatment of adult gastroenteritis 1

Monitoring and Follow-Up

Assess for complications requiring escalation of care:

• Monitor for signs of worsening dehydration: decreased urine output, altered mental status, poor skin turgor, dry mucous membranes 2
• Reassess hydration status after 2-4 hours of oral rehydration; if still dehydrated, reestimate deficit and restart rehydration 2
• Obtain stool studies (including C. difficile testing) for symptoms lasting >7 days, bloody diarrhea, recent antibiotic use, or severe symptoms 2, 5

Infection Control

Prevent transmission to others:

• Practice proper hand hygiene after using toilet, before food preparation and eating, and after handling soiled items 2
• Use gloves and gowns when caring for people with diarrhea 2
• Clean and disinfect contaminated surfaces promptly 2
• Separate ill persons from well persons until at least 2 days after symptom resolution 2

Common Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic testing—initiate rehydration promptly 2
• Do not use inappropriate fluids like sports drinks as primary rehydration in moderate to severe dehydration 2
• Do not unnecessarily restrict diet during or after rehydration—early refeeding is beneficial 1, 2
• Do not use antimotility drugs in bloody diarrhea or high fever as this may worsen outcomes 1, 2
• Do not prescribe antimicrobials empirically for uncomplicated viral gastroenteritis in immunocompetent adults 2