Lomotil Dosing for Diarrhea
The FDA-approved adult dose of Lomotil is 2 tablets (5 mg diphenoxylate) four times daily initially (20 mg/day total), reduced to as little as 2 tablets daily once control is achieved, though loperamide is strongly preferred as first-line therapy due to superior efficacy and safety profile. 1
Standard Adult Dosing
- Initial dose: 2 tablets (5 mg diphenoxylate) four times daily (20 mg/day total) 1
- Maintenance dose: Reduce to individual requirements once control is achieved; often maintained with as little as 5 mg (2 tablets) daily 1
- Expected response time: Clinical improvement should occur within 48 hours for acute diarrhea 1
- Maximum trial duration: If no improvement after 10 days at maximum dose (20 mg/day) in chronic diarrhea, further treatment is unlikely to help 1
Critical Safety Warnings
Lomotil should NOT be your first-line agent - the American Gastroenterological Association recommends loperamide instead because it is more effective with fewer central nervous system and peripheral side effects. 2, 3
Absolute Contraindications:
- Never use in children under 2 years of age 1
- Never use in severe dysentery with high fever or bloody stools 2
- Never use in suspected infectious diarrhea from invasive organisms (Shigella, Salmonella, STEC) 2, 4
Pediatric Considerations
- Not recommended under 2 years of age 1
- Use with special caution in young children 1
- For children under 13 years: Use only oral solution, not tablets 1
- One older study used 0.3 mg/kg/day in children 6 weeks to 2 years, but current guidelines advise against use in this age group 5
Why Loperamide is Preferred
Loperamide should be your first choice with an initial dose of 4 mg followed by 2 mg every 2-4 hours or after each unformed stool (maximum 16 mg daily). 6, 3
Advantages of loperamide over Lomotil:
- More effective for acute diarrhea 3
- Fewer central nervous system effects 2, 7
- Fewer peripheral side effects 3
- Available over-the-counter 7
- Local gut activity with minimal systemic absorption 6
When Lomotil Might Be Considered
Lomotil is relegated to third-line therapy in cancer patients with therapy-associated diarrhea, only after loperamide and octreotide have failed, and only after excluding infectious causes. 2
Requirements before using Lomotil:
- Rule out infectious etiology completely 2
- Ensure no bloody stools or high fever 2
- Verify loperamide has been tried and failed 2
- Assess nutritional status and hydration 1
Common Pitfalls to Avoid
- Do not exceed 20 mg/day in adults - higher doses increase toxicity without added benefit 1
- Monitor for anticholinergic effects from the atropine component (dry mouth, blurred vision, urinary retention) 8
- Watch for paralytic ileus - more prolonged intestinal transit occurs with diphenoxylate-atropine than loperamide 3
- Avoid in bacterial dysentery - can worsen outcomes by prolonging pathogen contact time with intestinal mucosa 4