Pepto Bismol (Bismuth Subsalicylate) Dosing and Usage
For acute diarrhea or gastrointestinal upset in adults, take 2 chewable tablets (524 mg) every 30-60 minutes, not exceeding 8 doses (4.2 grams) in 24 hours, and discontinue after 2 days maximum. 1
Standard Dosing for Common Gastrointestinal Symptoms
Acute Diarrhea
- Adults and children ≥12 years: 2 chewable tablets every 30 minutes OR 4 tablets every hour as needed 1
- Maximum: 8 doses (approximately 15 chewable tablets or 4.2 grams) per 24 hours 1
- Duration: Use until diarrhea stops but not more than 2 days 1
- Drink plenty of clear fluids to prevent dehydration 1
Upset Stomach, Heartburn, Indigestion, Nausea
- Adults and children ≥12 years: 2 chewable tablets every 30-60 minutes as needed 1
- Same maximum daily dose applies (8 doses/24 hours) 1
Pediatric Considerations
- Children <12 years: Consult a physician before use 1
- The American College of Gastroenterology advises against use in children and adolescents with viral illness due to Reye's syndrome risk 2
Specialized Clinical Applications
H. pylori Eradication (Quadruple Therapy)
When bismuth subsalicylate is used as part of H. pylori treatment, the dosing differs significantly:
- Bismuth subcitrate: 120-140 mg taken 3-4 times daily for 14 days 2, 3
- Timing: Administer 30 minutes before meals along with PPI; antibiotics given 30 minutes after meals 2
- Must be combined with metronidazole, tetracycline, and a proton pump inhibitor 3
Microscopic Colitis
- Dose: 8-9 tablets divided three times daily (approximately 2.6-3.0 grams daily) 2
- This represents a conditional recommendation due to low-quality evidence 2
Critical Safety Contraindications
Absolute contraindications per the American College of Gastroenterology 2:
- Aspirin allergy or sensitivity
- Concurrent high-dose aspirin therapy
- Children/adolescents with viral illness (Reye's syndrome risk)
- Pregnancy (inadequate safety data for salicylate content)
Drug Interaction Timing
With Proton Pump Inhibitors (PPIs)
- Wait at least 2 hours before or after taking PPIs when using bismuth subsalicylate as an antacid 4
- Antacids neutralize stomach acid, creating a pH environment that compromises PPI dissolution and activation 4
- For breakthrough symptoms while on PPIs, maintain proper timing separation 4
Pharmacokinetics and Safety Profile
Absorption and Metabolism
- Salicylate portion is extensively absorbed (>90%) and excreted in urine 5
- Bismuth absorption is minimal (<0.005%) from the gastrointestinal tract 5
- Maximum daily dose (4.2 grams) produces peak salicylate concentrations well below toxicity levels 5
Extended Use Safety
- Safe for acute indications and up to 3-4 weeks of extended dosing 5
- Extended dosing at 3.14 g/day for 6 weeks produced mean blood bismuth concentrations (16.1 ± 7.9 ng/g) considerably below neurotoxicity thresholds 5
Mechanism of Action
Bismuth subsalicylate works through multiple mechanisms 6, 7:
- Antisecretory effects: Inhibits fluid accumulation from bacterial enterotoxins (74-97% inhibition) 6
- Antimicrobial effects: Direct action against enteric pathogens 7
- Anti-inflammatory properties: Reduces inflammatory diarrhea through prostaglandin inhibition 6
Clinical Efficacy Considerations
Comparative Effectiveness
- Loperamide provides faster and more effective relief than bismuth subsalicylate for acute nonspecific diarrhea 8
- Bismuth subsalicylate has modest therapeutic effect on acute diarrhea but does not prevent progression to persistent diarrhea 9
- 62-76% effective in preventing traveler's diarrhea when used prophylactically 7
Common Pitfalls to Avoid
- Do not exceed 2 days of use for self-treatment of diarrhea without medical evaluation 1
- Do not substitute doxycycline for tetracycline in H. pylori quadruple therapy, as results are significantly inferior 3
- Fully chew tablets before swallowing for optimal effectiveness 1
- Avoid in pregnancy despite over-the-counter availability 2