Pepto-Bismol (Bismuth Subsalicylate) Liquid Dosing
For adults and children 12 years and older, the FDA-approved dose is 30 mL (2 tablespoons) every 30 minutes to 1 hour as needed, not exceeding 8 doses (240 mL) in 24 hours. 1
Adult Dosing
For Acute Diarrhea or GI Upset
- Standard dose: 30 mL every 30 minutes OR 60 mL every hour as needed 1
- Maximum: 8 doses (240 mL total) in 24 hours 1
- Duration: Use until diarrhea stops but not more than 2 days 1
- For upset stomach, heartburn, indigestion, or nausea, the same dosing applies 1
For Helicobacter pylori Eradication
- Dose: 2 tablets or 2 capsules four times daily, taken 30 minutes before meals 2
- This is used as part of bismuth quadruple therapy with tetracycline HCl 500 mg four times daily, metronidazole 500 mg four times daily, and a proton pump inhibitor twice daily 2
- Treatment duration: 14 days 2
Pediatric Dosing
Children Under 12 Years
- FDA recommendation: Ask a doctor before use 1
- Research supports dosing at 100 mg/kg/day divided over multiple doses for up to 5 days in children aged 4-36 months with acute diarrhea 3
- This pediatric dosing showed modest therapeutic benefit with no detected toxicity 3
Important Clinical Considerations
Safety Profile
- Bismuth subsalicylate is converted to salicylic acid (>90% absorbed) and insoluble bismuth salts (<0.005% absorbed) in the GI tract 4
- The maximum daily dose of 4.2 g produces plasma salicylate concentrations well below toxic levels 4
- Extended dosing for up to 3-4 weeks has been shown safe, with blood bismuth levels remaining far below neurotoxic thresholds 4
Hydration
- Critical: Patients should drink plenty of clear fluids to prevent dehydration caused by diarrhea 1
Comparative Efficacy
- Loperamide provides faster and more effective relief than bismuth subsalicylate for acute diarrhea, though both are well-tolerated 5
- Bismuth subsalicylate at 30 mL every half hour for 8 doses is significantly more effective than placebo in reducing diarrhea frequency 6
Common Pitfalls
- Do not exceed the maximum 8 doses in 24 hours to avoid salicylate accumulation 1
- Avoid use beyond 2 days for acute symptoms without medical consultation 1
- Be aware that bismuth subsalicylate contains salicylate—consider total salicylate load if patient is taking other salicylate-containing medications 4