Treatment of Diarrhoea

Overview

1. Rehydration - The Cornerstone

WHO Three-Plan Approach (for children and adults)

• Give extra fluids (ORS, soup, rice water, yoghurt drinks, or clean water)
• Volumes: 50-100 ml after each loose stool (children under 2 years); 100-200 ml after each loose stool (2 years and above)
• Give frequent small sips from a cup
• If vomiting occurs: wait 10 minutes, then continue more slowly
• Continue breastfeeding (infants)

• Give ORS over 4 hours based on body weight (weight x 75 ml = approximate volume in ml):
  • Under 6 kg: 200-450 ml
  • 6 to under 10 kg: 450-800 ml
  • 10 to under 12 kg: 800-960 ml
  • 12-19 kg: 960-1600 ml
• Reassess after 4 hours and reclassify

• IV Ringer's lactate or normal saline; add ORS as tolerated
• Required when patient cannot drink, has rapid/weak pulse, or is in shock
• Indicated especially for V. cholerae and ETEC causing massive fluid losses

ORS Composition (WHO Formula)

2. Zinc Supplementation (Children under 5 years)

3. Symptomatic (Antidiarrhoeal) Agents

Loperamide (Antimotility)

• Indications: mild to moderate watery diarrhoea without fever or blood in stool
• Adult dose: 4 mg initially, then 2 mg after each unformed stool, up to 16 mg/day maximum
• Avoid in: bloody/mucoid stool, high fever, suspected Shiga toxin-producing E. coli (risk of haemolytic uraemic syndrome), children under 2 years
• Can prolong or worsen illness if used without specific antibiotic treatment

Bismuth Subsalicylate

• Dose: 524 mg every 30-60 minutes as needed, up to 8 doses/day (max 4200 mg/day)
• Useful for mild diarrhoea and viral gastroenteritis
• Avoid in children (salicylate toxicity risk), especially young children

4. Antibiotic Therapy

When to use antibiotics

• Moderate to severe illness with fever
• Bloody or mucous stools (dysentery)
• 6 or more stools in 24 hours
• Significant dehydration
• Underlying immunocompromising conditions
• Frail elderly

Empirical Therapy

Specific Organism-Directed Therapy

• Shigella: Azithromycin or ciprofloxacin (where sensitive)
• C. difficile: Vancomycin (oral) or fidaxomicin; metronidazole for mild disease
• Giardia: Metronidazole 400 mg TID x 5 days
• Entamoeba histolytica: Metronidazole 800 mg TID x 10 days, followed by luminal agent (diloxanide furoate or paromomycin)
• Cholera: Oral rehydration + single-dose doxycycline 300 mg (adults)

5. Dietary Management

• Continue feeding - do not starve the patient
• For infants: continue breastfeeding throughout the illness
• For older children/adults: plain foods (rice, bananas, toast, yoghurt) are well tolerated
• Avoid high-fat, high-sugar, or very high-fibre foods during acute illness

6. Indications for IV Therapy / Hospital Admission

• Severe dehydration (sunken eyes, skin turgor poor, lethargic, not drinking)
• Shock or altered consciousness
• Persistent vomiting preventing oral intake
• Failure of ORS therapy
• Very young infants (under 3 months) with any degree of dehydration

7. What NOT to Use

• Probiotics: Not useful as treatment for acute infective diarrhoea (evidence does not support routine use in treatment, though may help prevent antibiotic-associated diarrhoea)
• Antimotility agents in dysentery or suspected STEC infection
• Antibiotics in mild, viral, uncomplicated diarrhoea - raises risk of C. difficile and promotes acquisition of MDR organisms

Summary Flow

Acute Diarrhoea
├─ Assess dehydration severity
│   ├─ None → Plan A (home ORS + zinc + continue feeding)
│   ├─ Some → Plan B (ORS in clinic over 4 hours)
│   └─ Severe → Plan C (IV fluids urgently)
│
├─ No fever/blood in stool? → Loperamide for symptom relief
│
└─ Antibiotic criteria met?
    ├─ No → supportive care only
    └─ Yes → Azithromycin (first choice)
               ├─ SE Asia / South Asia → Azithromycin preferred
               └─ Non-invasive traveller's diarrhoea → Rifaximin