Treatment of Diarrhoea: OPD and IPD

Definitions & Initial Assessment

CORE PRINCIPLE: Three Goals of Treatment (Both OPD & IPD)

1. Prevent or treat dehydration
2. Replace ongoing fluid losses
3. Meet nutritional needs

OPD Management (Outpatient)

1. Oral Rehydration Therapy (ORT) - Cornerstone

• No dehydration: Continue normal feeding; give 10 mL/kg ORS for each loose stool
• Mild-moderate dehydration: 50-100 mL/kg ORS over 3-4 hours, then reassess
• Dilute apple juice followed by child's preferred fluids is acceptable in children with minimal dehydration in high-income settings (Tintinalli's)

2. Diet & Nutrition

• Do NOT fast the patient - early feeding reduces illness duration
• Continue breastfeeding in infants
• Resume normal diet as soon as possible (BRAT diet is no longer recommended as the sole diet)
• Avoid dairy temporarily only if lactose intolerance is suspected
• Good nutrition is important even if vomiting or diarrhoea persists (Tintinalli's)

3. Antimotility Agents (OPD - selected cases only)

• Shortens symptom duration when combined with antibiotics
• Suitable for: watery diarrhoea, traveller's diarrhoea, non-inflammatory causes
• Contraindicated in: bloody/mucoid diarrhoea, suspected C. difficile, Shiga toxin-producing E. coli (risk of toxic megacolon, haemolytic uraemic syndrome), children <2 years

4. Antibiotics (OPD - selective use)

• Dysentery (bloody stool + fever)
• Severe illness, immunocompromised patient
• Traveller's diarrhoea with systemic features
• Stool cultures confirming a susceptible pathogen

Note: Most viral gastroenteritis (rotavirus, norovirus) requires no pharmacological treatment - supportive care only (Goldman-Cecil)

5. Adjunctive Agents (OPD)

• Children: 20 mg/day (10 mg for infants ≤6 months) x 10-14 days
• Reduces duration and severity of diarrhoea
• WHO-recommended especially in developing countries
• Also reduces duration of shigellosis (Goldman-Cecil)

• Safe and beneficial alongside rehydration therapy
• Moderate evidence for Lactobacillus GG and Saccharomyces boulardii in acute gastroenteritis (Tintinalli's)

IPD Management (Inpatient)

Indications for Admission

• Severe dehydration (>10% body weight loss, shock)
• Inability to tolerate oral fluids (persistent vomiting)
• Altered mental status
• Extremes of age (infants, elderly)
• Bloody diarrhoea with systemic toxicity
• Electrolyte imbalances (severe hyponatraemia, hypokalaemia)
• Comorbidities (diabetes, renal failure, immunocompromised)
• Suspected surgical abdomen

1. Intravenous Rehydration (IPD)

• Restore intravascular volume rapidly
• Severe dehydration: 100 mL/kg IV fluid total during this phase
• Preferred solution: Lactated Ringer's (closest to cholera stool electrolytes) OR Normal Saline

• Replace ongoing losses + daily requirements
• IV maintenance fluid: typically Ringer's Lactate or 0.45% NaCl + dextrose
• Monitor and replace potassium as needed (avoid hypokalaemia)
• Transition to ORS as soon as oral tolerance is established

2. IV Antibiotics (IPD)

3. Monitoring (IPD)

• Hourly urine output (target >0.5 mL/kg/hr)
• Electrolytes (Na⁺, K⁺, HCO₃⁻) every 4-6 hours initially
• Blood glucose (especially in children - risk of hypoglycaemia)
• Stool input/output charting
• Stool culture and sensitivity (if not done as outpatient)
• CBC, renal function
• Blood cultures if systemic sepsis suspected

4. Special Considerations (IPD)

• Stop the offending antibiotic if possible
• Lactose-free diet
• Avoid antimotility agents (risk of toxic megacolon)
• Treat with metronidazole or vancomycin (Goldman-Cecil)

• IV Ringer's Lactate 100 mL/kg in the rehydration phase
• Early transition to ORS once vomiting controlled
• Antibiotic reduces duration and fluid losses: Doxycycline, Azithromycin, or Ciprofloxacin (Goldman-Cecil)

• ORT remains first-line even if vomiting is mild (give small frequent sips, 5 mL every minute)
• IV only for severe dehydration, haemodynamic compromise, or unsafe oral intake
• Cochrane review: no difference in failure to rehydrate between ORT and IV; ORT associated with shorter hospital stay (Tintinalli's)
• Zinc supplementation throughout illness
• Avoid antidiarrhoeal/antimotility agents in children (Harriet Lane Handbook)

Summary Algorithm

Diarrhoea patient
      |
      ├─ Assess dehydration severity
      |
      ├── NO/MILD dehydration → OPD
      |       ├── ORS (WHO low-osmolarity)
      |       ├── Early refeeding
      |       ├── Zinc (children)
      |       ├── Antibiotics only if dysentery/invasive features
      |       ├── Loperamide only if watery, non-bloody
      |       └── Discharge with advice + return precautions
      |
      └── MODERATE/SEVERE dehydration → ADMIT (IPD)
              ├── IV Ringer's Lactate (100 mL/kg rehydration phase)
              ├── Electrolyte monitoring + replacement
              ├── IV antibiotics if systemic toxicity / bloody stool
              ├── Stool culture + sensitivity
              ├── Transition to ORS as soon as tolerated
              └── Zinc + probiotics as adjuncts