What is the recommended management for acute gastroenteritis, including rehydration, diet, antiemetics, antidiarrheals, antibiotics, and follow‑up?

Management of Acute Gastroenteritis

Oral rehydration solution (ORS) is the first-line treatment for mild to moderate dehydration in acute gastroenteritis, with intravenous fluids reserved only for severe dehydration (≥10% fluid deficit), shock, altered mental status, or failure of oral rehydration. 1

Initial Assessment

Assess dehydration severity through specific clinical signs to guide treatment intensity 1:

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

Measure body weight if possible, as acute weight change is the most accurate assessment of fluid status 1. Prolonged skin retraction time and abnormal capillary refill are more reliable predictors than sunken fontanelle or absence of tears 1.

Rehydration Protocol

Mild Dehydration (3-5% deficit)

• Administer 50 mL/kg of ORS containing 50-90 mEq/L sodium over 2-4 hours 1
• Start with small volumes (one teaspoon) using a syringe or medicine dropper, gradually increasing as tolerated 1
• Reassess hydration status after 2-4 hours 1
• If rehydrated, progress to maintenance therapy; if still dehydrated, reestimate deficit and restart rehydration 1

Moderate Dehydration (6-9% deficit)

• Administer 100 mL/kg of ORS over 2-4 hours using the same small-volume technique 1
• Reassess after 2-4 hours and adjust accordingly 1

Severe Dehydration (≥10% deficit)

• This is a medical emergency requiring immediate IV rehydration 1
• Administer 20 mL/kg boluses of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 1
• May require two IV lines or alternate access sites (venous cutdown, femoral vein, intraosseous infusion) 1
• Once consciousness returns and patient can tolerate oral intake without ileus, transition to ORS for remaining deficit 1

No Dehydration

• Skip rehydration phase and begin maintenance therapy immediately 1

Replacement of Ongoing Losses

Replace ongoing stool and vomit losses continuously during both rehydration and maintenance phases 1:

• 10 mL/kg of ORS for each watery or loose stool 1
• 2 mL/kg of ORS for each vomiting episode 1
• If losses can be measured accurately, administer 1 mL of ORS for each gram of diarrheal stool 1

Dietary Management

Resume age-appropriate diet immediately during or after rehydration is complete—do not delay feeding 1:

• Breastfed infants: Continue nursing on demand throughout the illness 1
• Bottle-fed infants: Administer full-strength, lactose-free or lactose-reduced formulas immediately upon rehydration 1
• If lactose-free formulas unavailable, use full-strength lactose-containing formulas under supervision 1
• Only reduce or remove lactose if true intolerance develops (worsening diarrhea upon introduction of lactose-containing foods) 1
• Older children: Continue usual diet including starches, cereals, yogurt, fruits, and vegetables 1
• Avoid foods high in simple sugars and fats 1

Antiemetic Therapy

• Ondansetron may be given to children >4 years and adolescents with significant vomiting to facilitate oral rehydration 1
• Use only after attempting small-volume ORS administration (5-10 mL every 1-2 minutes) 2
• Antiemetics are not a substitute for fluid and electrolyte therapy 1

Antidiarrheal Medications

Antimotility agents should NOT be used in children <18 years with acute diarrhea 1:

• Loperamide is contraindicated in all children <18 years due to risk of serious adverse events including ileus and deaths 1
• In immunocompetent adults with acute watery diarrhea, loperamide may be given once adequately hydrated 1
• Avoid loperamide at any age if inflammatory diarrhea, bloody diarrhea, or fever present due to risk of toxic megacolon 1

Antibiotic Therapy

Antibiotics are NOT routinely indicated for acute gastroenteritis 1:

• Consider antibiotics only when:
  • Dysentery (bloody diarrhea) with fever is present 1
  • Watery diarrhea persists >5 days 1
  • Stool cultures, microscopy, or epidemic setting indicate a specific treatable pathogen 1
• Most acute gastroenteritis is viral and self-limited, requiring no antimicrobial therapy 1

Adjunctive Therapies

• Probiotics may be offered to reduce symptom severity and duration in immunocompetent adults and children 1
• Zinc supplementation (10-20 mg daily) reduces diarrhea duration in children 6 months to 5 years in areas with high zinc deficiency prevalence or in malnourished children 1

Follow-up and Monitoring

• Monitor hydration status frequently during treatment by assessing skin turgor, mucous membranes, mental status, and urine output 2
• Continue ORS replacement of ongoing losses until diarrhea and vomiting resolve 1
• Stool cultures are indicated for dysentery but not needed for typical acute watery diarrhea in immunocompetent patients 1

Critical Pitfalls to Avoid

• Do not use sports drinks, juices, or soft drinks for rehydration—they contain inadequate sodium and excessive sugar that worsens diarrhea through osmotic effects 2
• Do not delay feeding or use restrictive diets—early refeeding reduces illness severity and duration 1
• Do not give antimotility agents to children or patients with bloody diarrhea/fever 1
• Do not use metoclopramide—it has no role in gastroenteritis management and may worsen outcomes 2
• Do not withhold ORS while awaiting diagnostic testing—begin rehydration immediately based on clinical assessment 2
• Nasogastric ORS administration may be considered if patient cannot tolerate oral intake but has normal mental status 1