Drug of Choice for Persistent Diarrhea
Loperamide is the drug of choice for persistent diarrhea in otherwise healthy adults without warning signs. 1, 2
When Loperamide is Appropriate
Loperamide should be used for symptomatic relief in adults with persistent non-bloody diarrhea who can maintain adequate fluid intake and have no fever, dysentery, or severe dehydration. 2, 3
Specific Dosing Regimen
- Initial dose: 4 mg (two 2-mg capsules) immediately, followed by 2 mg after each unformed stool 3
- Maximum daily dose: 16 mg (eight capsules) per 24 hours 3
- Expected response: Clinical improvement typically occurs within 48 hours 3
- For chronic persistent diarrhea, once optimal control is achieved, the maintenance dose averages 4-8 mg daily and can be given as a single or divided dose 3
Critical Contraindications - When NOT to Use Loperamide
Do not use loperamide if any of the following are present: 2, 3
- Bloody stools or dysentery - indicates invasive bacterial infection where slowing motility increases risk of toxic megacolon 2
- High fever >38.5°C - suggests inflammatory or invasive infection 1, 2
- Severe dehydration, altered mental status, or shock - rehydration must be completed first 2
- Abdominal distension - may indicate ileus or toxic megacolon 1, 2
- Children under 2 years of age - risk of respiratory depression and cardiac adverse reactions 3
Why Loperamide is Superior
The evidence strongly supports loperamide over alternatives: 1
- More effective than older antidiarrheals (diphenoxylate) and over-the-counter bismuth subsalicylate 4
- Does not prolong illness - the outdated belief that antimotility agents "trap toxins" is not evidence-based 2, 5
- Safe in infectious diarrhea - controlled trials demonstrate no worsening of outcomes in non-dysenteric infections caused by E. coli, Shigella, Campylobacter, or Salmonella 2, 5
- Low side-effect profile with minimal abuse potential 4, 6
Essential Supportive Measures
While loperamide is the drug of choice, concurrent management is critical: 2
- Maintain fluid intake guided by thirst using glucose-containing drinks or electrolyte-rich soups 2
- Continue normal eating guided by appetite - fasting provides no benefit 2
- Formal oral rehydration solutions are not needed for healthy adults who can maintain adequate fluid intake 1, 2
When to Escalate Care
Seek immediate medical attention if: 1, 2
- No improvement within 48 hours of starting loperamide 1, 3
- Development of fever >38.5°C, bloody stools, or severe vomiting 1, 2
- Signs of worsening dehydration or abdominal distension 1, 2
- Patient is frail, elderly (>75 years), immunocompromised, or has significant chronic disease 1, 2
Common Pitfalls to Avoid
- Do not withhold loperamide in non-dysenteric infectious diarrhea - large randomized trials show positive rather than negative effects when used appropriately 5
- Do not exceed 16 mg daily - higher doses increase cardiac adverse reaction risk without additional benefit 3
- Do not use in patients taking QT-prolonging medications without careful consideration, especially in elderly patients 3
- Do not delay rehydration while initiating loperamide - fluid replacement remains the cornerstone of therapy 2