What is the best way to manage watery diarrhea?

Management of Watery Diarrhea

For most patients with acute watery diarrhea without recent international travel, empiric antimicrobial therapy is not recommended; instead, focus on oral rehydration solution (ORS) as first-line therapy, with treatment intensity determined by the degree of dehydration. 1

Initial Assessment

Assess the degree of dehydration through physical examination to guide therapy intensity 1:

• Mild dehydration (3-5% fluid deficit): Increased thirst, slightly dry mucous membranes 1
• Moderate dehydration (6-9% fluid deficit): Loss of skin turgor, skin tenting when pinched, dry mucous membranes 1, 2
• Severe dehydration (≥10% fluid deficit): Severe lethargy or altered consciousness, prolonged skin tenting (>2 seconds), cool and poorly perfused extremities, decreased capillary refill 1, 3

Key clinical pearl: Rapid deep breathing, prolonged skin retraction time, and decreased perfusion are more reliable indicators of dehydration than sunken fontanelle or absence of tears 1, 3

Rehydration Strategy Based on Severity

Mild Dehydration (3-5% Fluid Deficit)

• Administer reduced osmolarity ORS containing 50-90 mEq/L sodium at 50 mL/kg over 2-4 hours 1
• Start with small volumes (one teaspoon) using a teaspoon, syringe, or medicine dropper, then gradually increase as tolerated 1, 2
• Reassess hydration status after 2-4 hours 1, 2

Moderate Dehydration (6-9% Fluid Deficit)

• Administer ORS at 100 mL/kg over 2-4 hours using the same gradual approach 1, 2, 4
• For patients unable to tolerate oral intake, consider nasogastric administration of ORS at 15 mL/kg/hour 1, 4
• Reassess after 2-4 hours; if still dehydrated, reestimate fluid deficit and restart rehydration 1, 2

Severe Dehydration (≥10% Fluid Deficit)

This constitutes a medical emergency requiring immediate IV rehydration 1, 3:

• Administer boluses of 20 mL/kg of lactated Ringer's solution or normal saline until pulse, perfusion, and mental status normalize 1
• Continue IV rehydration until the patient awakens, has no aspiration risk, and has no evidence of ileus 1
• Once mental status normalizes, the remaining deficit can be replaced with ORS 1

Replacement of Ongoing Losses

Critical step: Replace ongoing stool and vomit losses continuously throughout both rehydration and maintenance phases 1, 2:

• Children <10 kg: 60-120 mL ORS for each diarrheal stool or vomiting episode (up to ~500 mL/day) 2, 4
• Children >10 kg: 120-240 mL ORS for each diarrheal stool or vomiting episode (up to ~1 L/day) 2, 4
• Adolescents and adults: Ad libitum, up to ~2 L/day 2

Nutritional Management

• Continue breastfeeding throughout the diarrheal episode in infants and children 1, 2
• Resume age-appropriate usual diet during or immediately after rehydration is completed 1, 2
• Avoid "resting the bowel" through fasting 3
• For bottle-fed infants, use full-strength, lactose-free, or lactose-reduced formulas immediately upon rehydration 4, 3

Antimicrobial Therapy: When NOT to Use

Empiric antimicrobial therapy is NOT recommended for most patients with acute watery diarrhea without recent international travel 1. This is a strong recommendation based on the low likelihood of bacterial pathogens requiring treatment and the self-limited nature of most viral causes.

Exceptions where empiric treatment may be considered 1:

• Immunocompromised patients with severe illness
• Young infants who are ill-appearing

Avoid empiric treatment in persistent watery diarrhea lasting ≥14 days 1

Adjunctive Therapies

Antiemetics

• Consider ondansetron for children >4 years of age with severe vomiting to facilitate oral rehydration 2

Antimotility Agents: Critical Contraindication

Loperamide is contraindicated in children <2 years of age due to risks of respiratory depression and serious cardiac adverse reactions 5. Even in older children, avoid loperamide in children <18 years of age with acute diarrhea 2. Loperamide should be used with special caution in pediatric patients due to greater variability of response, and dehydration (particularly in children <6 years) may further influence this variability 5.

Red Flags Requiring Urgent Referral

Refer immediately to gastroenterology or infectious disease specialists if 1, 6:

• Signs of severe dehydration or shock
• Bloody stools (suggests invasive pathogen)
• Persistent high fever
• Immunocompromised state or immunosuppressive therapy
• Altered mental status
• Clinical suspicion of sepsis or enteric fever

Infection Control Measures

Asymptomatic contacts should NOT receive empiric or preventive therapy but should follow appropriate infection prevention measures 1:

• Hand hygiene after toilet use, diaper changes, before food preparation 2

Common Pitfalls to Avoid

• Do not use soft drinks for rehydration due to high osmolality 3
• Do not obtain stool cultures routinely in immunocompetent patients with uncomplicated acute watery diarrhea 1
• Do not withhold feeding during rehydration; early refeeding improves outcomes 1, 2
• Do not use antimotility agents in children or when bloody diarrhea is present 2, 5