What is the primary treatment for acute gastroenteritis?

Primary Treatment for Acute Gastroenteritis

Oral rehydration solution (ORS) is the primary treatment for acute gastroenteritis in both children and adults with mild to moderate dehydration, with the goal of correcting fluid and electrolyte deficits while maintaining adequate nutrition. 1, 2

Initial Assessment and Categorization

Evaluate hydration status immediately through specific clinical signs: 1, 2

• Skin turgor (prolonged tenting >2 seconds indicates severe dehydration)
• Mental status (lethargy or altered consciousness signals severe dehydration)
• Mucous membrane moisture
• Capillary refill time
• Vital signs (tachycardia, hypotension)

Categorize dehydration severity: 1, 2

• Mild (3-5% body weight loss): Minimal clinical signs
• Moderate (6-9% body weight loss): Dry mucous membranes, decreased skin turgor, reduced urine output
• Severe (≥10% body weight loss): Altered mental status, prolonged skin tenting, poor perfusion, rapid deep breathing

Rehydration Strategy by Severity

Mild to Moderate Dehydration (First-Line Treatment)

Use low-osmolarity oral rehydration solution exclusively—not sports drinks, juice, or soda. 1, 2

Dosing for moderate dehydration (6-9% deficit): 1

• Administer 100 mL/kg ORS over 2-4 hours (e.g., 3,700 mL total for a 37 kg patient)
• For persistent vomiting: Start with 5-10 mL every 1-2 minutes using a spoon or syringe, gradually increasing as tolerated 1
• This small-volume technique successfully rehydrates >90% of children with vomiting without antiemetics 1

Replace ongoing losses: 1

• 10 mL/kg ORS for each watery stool
• 2 mL/kg ORS for each vomiting episode

Reassess after 2-4 hours: If still dehydrated, reestimate deficit and restart rehydration. 1

Severe Dehydration (Requires IV Therapy)

Reserve intravenous rehydration for: 1, 2

• Severe dehydration (≥10% deficit)
• Shock or altered mental status
• Failure of oral rehydration therapy after appropriate trial
• Intractable vomiting despite small-volume ORS administration
• Absent bowel sounds (ileus)

IV fluid protocol: 2, 3

• Use isotonic fluids: lactated Ringer's or normal saline
• Administer 20 mL/kg bolus over 30 minutes
• Continue until pulse, perfusion, and mental status normalize
• Transition to ORS to replace remaining deficit once patient improves

Alternative for moderate dehydration with oral intolerance: Nasogastric administration of ORS may be considered before escalating to IV therapy. 1, 3

Nutritional Management (Critical Component)

Resume age-appropriate diet during or immediately after rehydration—do not fast or restrict diet. 1, 2 Early refeeding reduces illness severity and duration. 1

• Continue breastfeeding throughout the diarrheal episode in infants 1, 2
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice) as they worsen diarrhea through osmotic effects 1

Pharmacological Adjuncts (Limited Role)

Antiemetics

Ondansetron may be given to children >4 years and adolescents with significant vomiting to facilitate oral rehydration. 1, 2 This can reduce the need for IV fluids and hospitalization. 4

Antimotility Agents

Loperamide is contraindicated in children <18 years with acute diarrhea. 1, 2, 3 It may be given to immunocompetent adults with acute watery diarrhea once adequately hydrated, but avoid in bloody diarrhea or fever. 1, 3

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 in areas with high zinc deficiency or malnutrition. 1, 2, 3

Antimicrobials

Antimicrobial agents have limited usefulness since viral agents predominate. 1 Consider only for: 1, 3

• Bloody diarrhea with fever and systemic toxicity
• Immunocompromised patients
• Specific identified bacterial pathogens (guided by culture)

Common Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic testing—initiate ORS immediately 1, 3
• Do not use inappropriate fluids (apple juice, sports drinks) as primary rehydration for moderate to severe dehydration 1
• Do not administer antimotility drugs to children or in cases of bloody diarrhea 1, 2
• Do not unnecessarily restrict diet during or after rehydration 1
• Do not underestimate dehydration in elderly patients who may not manifest classic signs 1

Infection Control

Practice proper hand hygiene, use gloves and gowns when caring for patients with diarrhea, clean contaminated surfaces promptly, and separate ill persons from well persons until at least 2 days after symptom resolution. 1, 2, 3