What are the clinical practice guidelines (CPG) for managing acute gastroenteritis in adults and children?

Management of Acute Gastroenteritis

Rehydration: The Cornerstone of Treatment

Oral rehydration solution (ORS) is the first-line treatment for mild to moderate dehydration in both children and adults with acute gastroenteritis. 1, 2

Assessment of Dehydration Severity

Categorize dehydration based on clinical examination 1:

• Mild (3-5% fluid deficit): Minimal clinical signs, slightly decreased urine output
• Moderate (6-9% fluid deficit): Loss of skin turgor with tenting when pinched, dry mucous membranes, decreased capillary refill 1
• Severe (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, rapid deep breathing indicating acidosis 1

The most reliable clinical predictors are prolonged skin retraction time, abnormal capillary refill, and rapid deep breathing—more accurate than sunken fontanelle or absence of tears 1. Acute weight change provides the most accurate assessment when premorbid weight is known 1.

ORS Administration Technique

For mild to moderate dehydration, administer low-osmolarity ORS using small, frequent volumes (5-10 mL every 1-2 minutes via spoon or syringe), gradually increasing as tolerated. 1 This technique successfully rehydrates >90% of children with vomiting and diarrhea without antiemetic medication 1.

Dosing for moderate dehydration (6-9% deficit): Administer 100 mL/kg ORS over 2-4 hours 1. Replace ongoing losses with 10 mL/kg ORS for each watery stool and 2 mL/kg for each vomiting episode 1. Reassess hydration status after 2-4 hours; if still dehydrated, reestimate deficit and restart rehydration 1.

Nasogastric administration may be considered for patients who cannot tolerate oral intake or refuse to drink adequately 1, 2.

Intravenous Rehydration

Reserve IV rehydration for severe dehydration (≥10% deficit), shock, altered mental status, failure of oral rehydration therapy, or ileus. 1, 2

Use isotonic fluids such as lactated Ringer's or normal saline 1. Continue IV rehydration until pulse, perfusion, and mental status normalize, then transition to ORS to replace remaining deficit 1, 2.

Nutritional Management

Resume age-appropriate diet during or immediately after rehydration—early refeeding is recommended rather than fasting or restrictive diets. 1, 2

Continue breastfeeding in infants throughout the diarrheal episode 1, 2. Avoid foods high in simple sugars (soft drinks, undiluted apple juice) as they can exacerbate diarrhea through osmotic effects 1. Limit or avoid caffeinated beverages (coffee, tea, energy drinks) as caffeine stimulates intestinal motility and worsens diarrhea 1.

Pharmacological Management

Antiemetics

Ondansetron may be given to children >4 years and adolescents to facilitate oral rehydration when vomiting is significant. 1, 2 This can increase success rate of oral rehydration therapy, decrease need for IV fluids, and reduce hospitalization rates 3, 4, 5.

Antimotility Agents

Loperamide is contraindicated in children <18 years with acute diarrhea. 1, 2, 6 The FDA label explicitly states loperamide is contraindicated in pediatric patients less than 2 years of age due to risks of respiratory depression and serious cardiac adverse reactions 6.

For immunocompetent adults with acute watery diarrhea, loperamide may be given once adequately hydrated, but avoid in inflammatory or febrile diarrhea due to risk of toxic megacolon. 1, 2 The FDA-approved dosing for adults is 4 mg initially, then 2 mg after each unformed stool, with maximum daily dose of 16 mg 6.

Probiotics and Zinc

Probiotics may reduce symptom severity and duration in both adults and children 1, 2. Zinc supplementation reduces diarrhea duration in children 6 months to 5 years of age in areas with high zinc deficiency prevalence or in malnourished children 1, 2.

Antimicrobial Therapy

Empiric antimicrobial therapy is NOT recommended in most patients with acute watery diarrhea without recent international travel. 2

Consider antimicrobials only in specific situations 1, 2:

• Immunocompromised patients with severe illness
• Ill-appearing infants <3 months with suspected bacterial etiology
• Fever, abdominal pain, and bloody diarrhea suggesting shigellosis
• Recent international travelers with fever ≥38.5°C or signs of sepsis
• Suspected enteric fever with sepsis

AVOID antimicrobials in STEC O157 and other Shiga toxin 2-producing E. coli infections, as they may increase risk of hemolytic uremic syndrome. 2

For patients requiring IV antibiotics (suspected enteric fever with sepsis, severe dehydration with suspected bacterial etiology), obtain blood, stool, and urine cultures first, then start broad-spectrum IV therapy 2. Transition to oral antibiotics once rehydrated with normalized vital signs 2.

Hospitalization Criteria

Admit patients with severe dehydration (≥10% fluid deficit), signs of shock, failure of oral rehydration therapy, altered mental status, intractable vomiting despite antiemetics, or significant comorbidities. 1

Lower thresholds for admission in 1:

• Elderly patients (≥65 years) due to higher mortality risk
• Immunocompromised patients (HIV, transplant recipients, malignancy, immunosuppressive therapy)
• Infants <3 months given higher risk of severe dehydration
• Bloody diarrhea with fever and systemic toxicity (monitor for hemolytic uremic syndrome)

Red Flags Requiring Immediate Medical Attention

Severe dehydration signs 1:

• Severe lethargy or altered consciousness
• Prolonged skin tenting (>2 seconds)
• Cool, poorly perfused extremities with decreased capillary refill
• Rapid, deep breathing indicating acidosis

Other critical red flags 1:

• Bloody stools with fever and systemic toxicity
• Persistent vomiting despite small-volume ORS administration (5-10 mL every 1-2 minutes)
• Absent bowel sounds (absolute contraindication to oral rehydration)
• Stool output >10 mL/kg/hour

Infection Control Measures

Practice proper hand hygiene after using toilet or changing diapers, before and after food preparation, before eating, and after handling soiled items. 1 Use gloves and gowns when caring for people with diarrhea 1. Clean and disinfect contaminated surfaces promptly 1. Separate ill persons from well persons until at least 2 days after symptom resolution 1.

Common Pitfalls to Avoid

• Never delay rehydration while awaiting diagnostic testing—initiate rehydration promptly 1
• Never use inappropriate fluids like apple juice or sports drinks as primary rehydration solutions for moderate to severe dehydration 1
• Never administer antimotility drugs to children or in cases of bloody diarrhea 1, 2
• Never unnecessarily restrict diet during or after rehydration 1
• Never underestimate dehydration in elderly patients, who may not manifest classic signs and have higher mortality risk 1
• Never give antimicrobials routinely for acute watery diarrhea—viral agents are the predominant cause 1, 2