What is the management plan for a patient presenting with watery diarrhea?

Management of Watery Diarrhea

Oral rehydration solution (ORS) with reduced osmolarity (<250 mmol/L) is the first-line treatment for all patients with watery diarrhea and mild to moderate dehydration, regardless of age or cause. 1, 2

Immediate Assessment and Rehydration Protocol

Assess Dehydration Severity

• Mild dehydration (3-5% fluid deficit): Examine for slightly dry mucous membranes, normal mental status, normal pulse 3
• Moderate dehydration (6-9% fluid deficit): Look for decreased skin turgor, dry mucous membranes, sunken eyes, decreased urine output 3
• Severe dehydration (≥10% fluid deficit): Assess for altered mental status, weak/rapid pulse, poor capillary refill, shock or pre-shock state 1, 3

Rehydration Strategy by Severity

For mild to moderate dehydration:

• Administer 50-100 mL/kg of reduced osmolarity ORS over 2-4 hours until clinical dehydration is corrected 1, 2
• For mild dehydration specifically: 50 mL/kg over 2-4 hours 3
• For moderate dehydration specifically: 100 mL/kg over 2-4 hours 3
• If vomiting is present, give small volumes (5-10 mL) every 1-2 minutes using a spoon or syringe, gradually increasing the amount 3
• Nasogastric administration may be used for moderate dehydration when oral intake is not tolerated 1, 2

For severe dehydration:

• Immediately administer intravenous isotonic fluids (lactated Ringer's or normal saline) at 60-100 mL/kg over the first 2-4 hours until pulse, perfusion, and mental status normalize 1, 4
• Once the patient awakens, has no aspiration risk, and has no ileus, transition to ORS to replace the remaining deficit 1
• Continue IV fluids if shock, altered mental status, ileus, or failure of ORS therapy persists 1

Ongoing Maintenance

• Replace ongoing stool losses with 10 mL/kg of ORS for each watery stool 3
• Replace vomiting losses with 2 mL/kg of ORS for each episode 3
• Continue maintenance fluids until diarrhea and vomiting resolve 1, 2

Nutritional Management

• Continue breastfeeding throughout the entire diarrheal episode without interruption 1, 2, 3
• Resume age-appropriate usual diet during or immediately after rehydration is completed 1, 2, 3
• For bottle-fed infants, resume full-strength formula immediately upon rehydration—do not dilute formula 1, 3
• Recommended foods include starches, cereals, yogurt, fruits, and vegetables; avoid foods high in simple sugars and fats 3

Adjunctive Therapies (Only After Adequate Hydration)

Antimotility Agents

• Loperamide is absolutely contraindicated in all children <18 years of age 1, 2, 3, 5
• Loperamide may be given to immunocompetent adults with acute watery diarrhea 1, 2
• Avoid loperamide in any patient with bloody diarrhea, fever, suspected inflammatory diarrhea, or risk of toxic megacolon 1, 2, 3
• Antimotility agents are not a substitute for fluid and electrolyte therapy—use only as ancillary treatment after adequate hydration 1, 2

Antiemetics

• Ondansetron may be given to children >4 years of age and adolescents with vomiting to facilitate oral rehydration tolerance 1, 2, 3
• Administer only after adequate hydration is achieved 3

Probiotics

• Probiotic preparations may be offered to reduce symptom severity and duration in immunocompetent patients with infectious or antimicrobial-associated diarrhea 1, 2, 3

Zinc Supplementation

• Administer oral zinc supplementation (20 mg daily for 10-14 days) to children 6 months to 5 years of age who reside in countries with high zinc deficiency prevalence or who show signs of malnutrition 1, 2, 3

Antimicrobial Therapy

• In most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is NOT recommended 2
• Consider empiric antibiotics only for: immunocompromised patients, ill-appearing young infants, suspected enteric fever, or dysentery with high fever 2, 3
• CRITICAL WARNING: Avoid antimicrobial therapy for STEC O157 and other Shiga toxin-producing E. coli due to increased risk of hemolytic uremic syndrome 2
• Avoid empiric treatment in persistent watery diarrhea lasting ≥14 days 2
• Azithromycin is the preferred first-line antibiotic when treatment is indicated (500 mg single dose for acute watery diarrhea) 6

Diagnostic Testing

• Most patients do not require laboratory workup or routine stool cultures 2
• Reserve diagnostic investigation for: severe dehydration or illness, persistent fever, bloody or mucoid stools, immunosuppression, or suspected nosocomial infection 2

Critical Pitfalls to Avoid

• Do NOT use commercial sports drinks (Gatorade), apple juice, or soft drinks for rehydration—they have inappropriate osmolarity and electrolyte composition 1, 2, 7
• Do NOT allow a thirsty child to drink large volumes of ORS ad libitum—this worsens vomiting 3
• Do NOT use antimotility agents as a substitute for fluid and electrolyte therapy 1, 2
• Do NOT treat asymptomatic contacts with antibiotics—advise infection control measures instead 1, 2
• Do NOT "rest the bowel"—this is an outdated practice; resume feeding immediately 7
• Do NOT dilute formula—use full-strength formula upon rehydration 1, 3

Warning Signs Requiring Immediate Medical Attention

• Severe dehydration with shock or near-shock 3
• Intractable vomiting preventing successful oral rehydration 3
• High stool output (>10 mL/kg/hour) 3
• Bloody diarrhea (dysentery) 3
• Decreased urine output, lethargy, or irritability 3
• No clinical improvement after 48 hours of treatment 5

Infection Control

• Perform hand hygiene after toilet use, diaper changes, before and after food preparation, before eating, and after handling garbage or animals 1, 3
• Use gloves, gowns, and hand hygiene with soap and water (or alcohol-based sanitizers) when caring for patients with diarrhea 1