What is the recommended hydration treatment for acute gastroenteritis?

Acute Gastroenteritis Hydration Management

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

Initial Assessment

Clinically evaluate dehydration severity using these specific physical findings 3, 2:

• Mild dehydration (3-5% fluid deficit): Slightly dry mucous membranes, normal mental status, normal capillary refill 3
• Moderate dehydration (6-9% fluid deficit): Sunken eyes, decreased skin turgor (skin retraction <2 seconds), pinched appearance, dry mucous membranes 3
• Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool poorly perfused extremities, decreased capillary refill, rapid deep breathing indicating acidosis 3

Measure body weight and assess recent fluid intake/output history 2, 4. The four-item Clinical Dehydration Scale based on physical examination is more reliable than laboratory studies for determining dehydration severity 4.

Rehydration Phase

Mild Dehydration (3-5%)

• Administer 50 mL/kg of ORS over 2-4 hours 3, 1
• Use low-osmolarity ORS formulations (50-90 mEq/L sodium) rather than sports drinks or juices 3, 2
• Start with small volumes (5-10 mL every 1-2 minutes using teaspoon, syringe, or medicine dropper), then gradually increase as tolerated 3, 1
• Reassess hydration status after 2-4 hours 3

Moderate Dehydration (6-9%)

• Administer 100 mL/kg of ORS over 2-4 hours using the same technique as mild dehydration 3
• If vomiting is significant, give small frequent volumes (5-10 mL) every 1-2 minutes with gradual increase 1
• Consider ondansetron for children >4 years to facilitate oral rehydration when vomiting impairs tolerance 2
• Nasogastric ORS administration may be used for patients who cannot tolerate oral intake but have normal mental status 1, 2

Severe Dehydration (≥10%)

This is a medical emergency requiring immediate intravenous therapy 3, 2:

• Administer boluses of 20 mL/kg of Ringer's lactate or normal saline until pulse, perfusion, and mental status normalize 3, 2
• May require two IV lines or alternate access sites (venous cutdown, femoral vein, intraosseous infusion) 3
• Once mental status normalizes, transition to ORS for remaining deficit replacement 3, 2

Maintenance Phase

Replace Ongoing Losses

• Administer 10 mL/kg of ORS for each watery/loose stool 3
• Give 2 mL/kg of ORS for each vomiting episode 3
• Continue ORS replacement until diarrhea and vomiting resolve 2

Nutritional Management

• Continue breastfeeding throughout the diarrheal episode in infants 1, 2
• Resume age-appropriate normal diet during or immediately after rehydration 1, 2
• Early refeeding is superior to fasting or restrictive diets 1, 2
• Avoid foods high in simple sugars (soft drinks, undiluted apple juice) as they worsen diarrhea through osmotic effects 2

Pharmacological Considerations

What NOT to Use

• Never give loperamide to children <18 years with acute diarrhea 1, 2
• Avoid antimotility drugs in inflammatory diarrhea, bloody diarrhea, fever, or suspected toxic megacolon 1
• Do not use adsorbents, antisecretory drugs, or toxin binders—they lack effectiveness 2
• Antimicrobials have limited usefulness since viral agents predominate; reserve for bloody diarrhea, recent antibiotic use, specific pathogen exposure, recent foreign travel, or immunodeficiency 2

What MAY Be Used

• Loperamide may be given to immunocompetent adults with acute watery diarrhea once adequately hydrated 1, 2
• Ondansetron for children >4 years when vomiting significantly impairs oral rehydration 2
• 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 2

Critical Pitfalls to Avoid

• Do not delay rehydration while awaiting diagnostic tests—initiate ORS immediately 2
• Do not use inappropriate fluids (apple juice, sports drinks) as primary rehydration for moderate-severe dehydration 2
• Do not unnecessarily restrict diet during or after rehydration 2
• Do not order routine stool cultures for mild viral gastroenteritis 4
• Recognize that ORS has a small failure rate: approximately 1 in 25 children will fail ORT and require IV therapy 5

When to Seek Medical Evaluation

Immediate evaluation needed for 1, 2:

• Inability to tolerate oral fluids despite antiemetic use
• Worsening signs of dehydration
• Development of bloody diarrhea
• Significant increase in fever
• Altered mental status or signs of shock