What is the best course of treatment for a patient with vomiting and diarrhea?

Treatment of Vomiting and Diarrhea

Reduced osmolarity oral rehydration solution (ORS) is the first-line treatment for patients with vomiting and diarrhea, regardless of age or cause, and should be initiated immediately to prevent or correct dehydration. 1

Initial Assessment

Assess dehydration severity by examining:

• Skin turgor, mucous membrane moisture, mental status, pulse rate, capillary refill time, and urine output 2
• Number of stools above baseline, stool composition (watery vs bloody), presence of nocturnal diarrhea 1
• Warning signs requiring escalation: fever, orthostatic symptoms (dizziness), severe abdominal cramping, weakness, altered mental status 1

Categorize dehydration severity:

• Mild (3-5% fluid deficit): Minimal clinical signs 2
• Moderate (6-9% fluid deficit): Decreased skin turgor, dry mucous membranes, reduced urine output 2
• Severe (≥10% fluid deficit): Marked signs plus altered mental status, weak pulse, poor perfusion 2

Rehydration Protocol

Mild to Moderate Dehydration

Administer reduced osmolarity ORS as first-line therapy for all patients with mild to moderate dehydration 1:

• For mild dehydration: 50 mL/kg ORS over 2-4 hours 2
• For moderate dehydration: 100 mL/kg ORS over 2-4 hours 2
• Replace each watery/loose stool with 10 mL/kg of ORS to maintain hydration 2
• Continue ORS until clinical dehydration is corrected 1

If vomiting occurs during ORS administration, wait 10 minutes then continue giving ORS more slowly in small sips at short intervals 3. Most fluid given is retained despite apparent vomiting 3.

Nasogastric administration of ORS may be used in patients with moderate dehydration who cannot tolerate oral intake, or in children with normal mental status who are too weak or refuse to drink adequately 1.

Severe Dehydration

Administer isotonic intravenous fluids (lactated Ringer's or normal saline) when there is severe dehydration, shock, altered mental status, failure of ORS therapy, or ileus 1:

• Continue IV rehydration until pulse, perfusion, and mental status normalize, the patient awakens, has no aspiration risk, and has no evidence of ileus 1
• Once stabilized, switch to ORS to replace the remaining fluid deficit 1
• In patients with ketonemia, initial IV hydration may be needed to enable tolerance of oral rehydration 1

Dietary Management

Resume age-appropriate normal diet immediately after rehydration is complete or during the rehydration process 1, 2:

• Continue breastfeeding throughout the illness in infants 1
• Children previously receiving lactose-containing formula can tolerate the same product in most instances 1
• Early feeding is as safe and effective as delayed feeding and improves nutritional outcomes 2
• Stop all lactose-containing products, alcohol, and high-osmolar supplements during acute phase 1

Pharmacological Management

Antiemetics

Ondansetron may be given to facilitate tolerance of oral rehydration in children >4 years of age and adolescents with acute gastroenteritis associated with vomiting 1:

• Typical dose: 4 mg for children 4-11 years 4
• Caution: Ondansetron can prolong QT interval; avoid in patients with congenital long QT syndrome, electrolyte abnormalities, congestive heart failure, or bradyarrhythmias 4
• Monitor for serotonin syndrome, especially with concomitant serotonergic drugs 4
• Do not use antiemetics as substitute for fluid and electrolyte therapy 1

Antimotility Agents

Loperamide should NOT be given to children <18 years of age with acute diarrhea 1, 2:

• Loperamide may be given to immunocompetent adults with acute watery diarrhea only after adequate hydration 1, 2
• Avoid loperamide at any age in suspected or proven inflammatory diarrhea, diarrhea with fever, or bloody diarrhea due to risk of toxic megacolon 1
• Contraindicated in children <2 years due to risk of respiratory depression and cardiac adverse reactions 5
• Higher than recommended doses can cause QT prolongation, Torsades de Pointes, cardiac arrest, and death 5

Antimicrobials

Empiric antimicrobial therapy is NOT recommended for acute watery diarrhea of suspected viral etiology 2:

• Antimicrobials should only be used when a specific bacterial pathogen is identified 1
• Antimicrobials may increase risk of hemolytic uremic syndrome in STEC infections 1

Adjunctive Therapies

Probiotic preparations may be offered to reduce symptom severity and duration in immunocompetent adults and children 1, 2.

Oral zinc supplementation reduces diarrhea duration in children 6 months to 5 years of age who reside in countries with high prevalence of zinc deficiency or who have signs of malnutrition 1.

Critical Pitfalls to Avoid

Do not use popular beverages like apple juice, Gatorade, or commercial soft drinks for rehydration—these lack appropriate electrolyte composition 1.

Do not withhold solid food for 24 hours—this practice is not supported by evidence and may worsen nutritional status 1.

Do not give loperamide if fever or bloody diarrhea develops, as this suggests bacterial or inflammatory etiology with risk of complications 2, 5.

Recognize that dehydration signs may be masked in hypernatremic patients 1.

Monitor closely for warning signs requiring hospitalization: persistent vomiting after rapid IV rehydration (especially with serum bicarbonate ≤13 mEq/L), inability to tolerate ORS, worsening dehydration despite treatment, or development of complications 6.