What is the best course of treatment for a patient, particularly the elderly, young children, or those with underlying medical conditions, presenting with diarrhea and vomiting?

Treatment of Diarrhea and Vomiting

Oral rehydration solution (ORS) is the first-line treatment for all patients with diarrhea and vomiting who have mild to moderate dehydration, regardless of age, and should be initiated immediately. 1

Initial Assessment and Triage by Dehydration Severity

Rapidly assess hydration status using clinical signs to determine treatment pathway 1, 2:

Mild Dehydration (3-5% fluid deficit)

• Clinical signs: Slightly dry mucous membranes, normal vital signs, mild thirst 2
• Treatment: Administer reduced osmolarity ORS (50-90 mEq/L sodium) at 50 mL/kg over 2-4 hours 1, 3

Moderate Dehydration (6-9% fluid deficit)

• Clinical signs: Sunken eyes, decreased skin turgor, tachycardia, reduced urine output 2
• Treatment: Administer ORS at 100 mL/kg over 2-4 hours 1, 3
• Alternative route: If oral intake fails, consider nasogastric ORS administration 1

Severe Dehydration (≥10% fluid deficit)

• Clinical signs: Altered mental status, poor perfusion, prolonged capillary refill, shock 2
• Treatment: This is a medical emergency requiring immediate IV rehydration 1
• IV protocol: Administer boluses of 20 mL/kg of lactated Ringer's or normal saline until pulse, perfusion, and mental status normalize 1
• Transition: Once stabilized and patient can tolerate oral intake, switch to ORS for remaining deficit replacement 1

ORS Administration Technique

Start small and increase gradually to maximize tolerance 1:

• Begin with 1 teaspoon (5 mL) using a syringe, medicine dropper, or spoon 1
• Gradually increase volume as tolerated 1
• Reassess hydration status after 2-4 hours 1, 2

Replacing Ongoing Losses

Critical pitfall: Failure to replace ongoing losses leads to treatment failure 1:

• Administer 10 mL/kg ORS for each watery stool 1, 2
• Administer 2 mL/kg ORS for each vomiting episode 1, 2
• Continue replacement until diarrhea and vomiting resolve 1

Nutritional Management

Resume age-appropriate diet immediately during or after rehydration—do not withhold food 1, 3:

• Infants: Continue breastfeeding on demand throughout illness 1
• Bottle-fed infants: Resume full-strength formula immediately after rehydration 1
• Older children: Continue usual diet including starches, cereals, yogurt, fruits, and vegetables 1
• Avoid: Foods high in simple sugars and fats 1

Early realimentation prevents malnutrition and may reduce stool output 4, 3.

Antiemetic Therapy for Persistent Vomiting

Ondansetron may facilitate ORS tolerance in children >4 years of age 1:

• Dose: 0.15-0.2 mg/kg oral (maximum 4 mg) 2
• Use only after adequate hydration attempts 1
• Not a substitute for fluid therapy 1

Antimotility Agents: Critical Safety Considerations

Loperamide is contraindicated in all children <18 years of age with acute diarrhea 1, 5:

• Risk of serious cardiac adverse reactions including QT prolongation, Torsades de Pointes, and sudden death 5
• Risk of respiratory depression in young children 5

In adults, loperamide may be used ONLY if 1, 3:

• Patient is immunocompetent 1
• Diarrhea is watery (not bloody) 1, 3
• No fever present 1
• Patient is adequately hydrated first 1, 3
• Maximum dose: 16 mg/day (8 capsules) 5

Never use loperamide if: Bloody diarrhea, fever, suspected inflammatory diarrhea, or toxic megacolon risk 1, 3, 5.

Antibiotic Therapy: When to Avoid and When to Consider

Do NOT prescribe antibiotics for typical acute watery diarrhea 4, 2, 3:

• Most cases are viral and antibiotics provide no benefit 4, 3
• Antibiotics promote resistance 2
• Critical danger: Antibiotics in STEC (Shiga toxin-producing E. coli) infection increase hemolytic uremic syndrome risk by up to 50% 2, 3

Consider antibiotics ONLY in these specific circumstances 3:

• Fever ≥38.5°C with clinical signs of sepsis 3
• Bloody diarrhea with severe illness (presumptive shigellosis) 3
• Immunocompromised state with severe symptoms 3
• Recent international travel with fever or sepsis signs 3

Adjunctive Therapies with Moderate Evidence

Probiotics may reduce symptom severity and duration 1, 4:

• Reduce mean diarrhea duration by approximately 25 hours 4
• Safe in immunocompetent patients 1
• Evidence quality is moderate 1

Zinc supplementation for specific populations 1:

• Children 6 months to 5 years in zinc-deficient regions 1, 3
• Children with signs of malnutrition 1
• Strong evidence for reduced diarrhea duration 1

Special Populations: Elderly and Those with Underlying Conditions

Elderly patients require heightened vigilance 5:

• More susceptible to QT prolongation from medications 5
• Avoid loperamide if taking Class IA or III antiarrhythmics 5
• Monitor closely for dehydration complications 5

Patients with underlying conditions:

• Use loperamide with caution in hepatic impairment due to increased systemic exposure 5
• No dose adjustment needed for renal impairment 5

Critical Pitfalls to Avoid

• Never dismiss persistent vomiting as benign—consider nasogastric ORS or IV fluids if oral route fails 1
• Never withhold food during diarrheal illness—early realimentation is beneficial 1, 3
• Never use antimotility agents in children or when fever/bloody diarrhea present—risk of serious complications 1, 3, 5
• Never prescribe antibiotics empirically for watery diarrhea—may cause harm in STEC infection 4, 2, 3
• Never use higher than recommended loperamide doses—cardiac arrest and death have been reported 5

Infection Control and Prevention

Hand hygiene is essential to prevent transmission 1:

• Wash hands with soap and water after toilet use, before eating, and before food preparation 1, 2
• Alcohol-based sanitizers are acceptable alternatives 1
• Use gloves and gowns when caring for patients with diarrhea 1