What are the risks and management strategies for Pepto Bismol (bismuth subsalicylate) overdose or excessive ingestion?

Pepto Bismol (Bismuth Subsalicylate) Ingestion: Risks and Management

Immediate Management of Overdose

In case of Pepto Bismol overdose, contact a Poison Control Center immediately and provide supportive care. 1

The primary concern with bismuth subsalicylate overdose involves two distinct toxicities:

• Salicylate toxicity (from the salicylate component, absorbed >90%)
• Bismuth neurotoxicity (from chronic excessive use, though <0.5% absorbed) 2

Acute Overdose: Salicylate Toxicity Risk

Risk Assessment

• The salicylate portion of bismuth subsalicylate is extensively absorbed (>90%) and excreted in urine, making acute salicylate toxicity the primary concern in overdose scenarios 2
• Maximum recommended daily dose (4.2 g of bismuth subsalicylate) produces peak salicylate concentrations considerably below toxic levels under normal use 2
• In acute overdose, treat as aspirin/salicylate poisoning with standard protocols including serum salicylate levels, acid-base status, and supportive care 2

Key Clinical Features of Salicylate Toxicity

• Tachypnea, respiratory alkalosis progressing to metabolic acidosis
• Tinnitus, altered mental status, hyperthermia
• Gastrointestinal symptoms (nausea, vomiting)
• Obtain salicylate levels, electrolytes, arterial blood gas, and renal function 2

Chronic Excessive Use: Bismuth Neurotoxicity

Clinical Presentation

• Progressive confusion and memory impairment developing over days to weeks 3, 4
• Multifocal myoclonus (involuntary jerking movements) 3, 4
• Gait instability and ataxia (difficulty walking, loss of coordination) 3, 4
• Visual hallucinations and psychosis 3
• Coarse postural tremors 4
• This presentation can mimic Creutzfeldt-Jakob disease due to rapidly progressive encephalopathy with myoclonus 4

Diagnostic Workup for Suspected Bismuth Toxicity

• Obtain serum and urine bismuth levels when chronic use is suspected and other causes are excluded 3
• Comprehensive evaluation should include: CBC, metabolic panel, CT head, MRI brain, EEG, lumbar puncture to exclude other causes 3
• EEG typically shows bihemispheric slowing 4
• Brain MRI is usually normal 3, 4

Treatment of Bismuth Neurotoxicity

• Immediately discontinue all bismuth-containing products 3, 4
• Provide supportive care and monitor for gradual improvement over weeks to months 3, 4
• Recovery timeline: Gradual improvement begins within 10 days, with resolution to baseline typically occurring over 4 months 3
• Physical therapy may be required for persistent gait disturbances 3
• Bismuth excretion in urine may continue for up to 3 months after discontinuation 5

Bismuth Level Interpretation

• Extended dosing (3.14 g/day for up to 6 weeks) produces mean blood bismuth concentrations of 16.1 ± 7.9 ng/g, well below neurotoxic levels 2
• Plasma concentrations >50 micrograms/L are associated with potential toxicity, though transient peaks after dosing are not necessarily harmful 5
• Chronic excessive use (e.g., 8 oz daily) can lead to toxic accumulation despite low bioavailability 4

Critical Contraindication: Pediatric Use

Bismuth subsalicylate (Pepto Bismol) should NEVER be administered to any person aged ≤18 years with suspected influenza or viral illness due to the risk of Reye's syndrome. 6

• This applies to all aspirin-containing products including bismuth subsalicylate 6
• For fever relief in children, use acetaminophen or non-steroidal anti-inflammatory drugs instead 6
• Children aged <4 years should not receive over-the-counter cold medications without consulting a healthcare provider first 6

Common Pitfalls and Caveats

Overlooked Chronic Toxicity

• Bismuth toxicity is rare and often overlooked because bismuth subsalicylate is an over-the-counter product perceived as safe 4
• Patients may not report chronic use unless specifically asked about all over-the-counter medications 3, 4
• The typical patient profile involves chronic gastrointestinal complaints (collagenous colitis, GERD, dyspepsia) leading to prolonged daily use 3

Delayed Recognition

• The subacute progressive nature of bismuth encephalopathy (developing over weeks) can delay diagnosis 4
• Consider bismuth toxicity in any patient with progressive encephalopathy, myoclonus, and ataxia, especially if other workup is unrevealing 4

Safe Use Duration

• Bismuth subsalicylate can be used safely for acute indications and for up to 3-4 weeks of extended dosing when used at recommended doses 2
• Chronic daily use beyond 4 weeks increases risk of bismuth accumulation and neurotoxicity 2, 3