Bismuth poisoning

Bismuth poisoning is a toxicologic disorder that can produce neuropsychiatric and multisystemic manifestations, with clinical features varying according to the dose, duration, and route of exposure. A distinctive presentation may include the combination of behavioural or personality change, myoclonus, ataxia, gastrointestinal symptoms, and prolonged exposure to a bismuth-containing medication or product.

Exposure clues include prolonged or excessive use of bismuth-containing medications, particularly bismuth subsalicylate and other oral bismuth preparations used for gastrointestinal symptoms or Helicobacter pylori eradication. Exposure may be overlooked when bismuth is obtained over the counter or used chronically for gastrointestinal complaints. Other exposures include certain bismuth-containing medicinal products and, historically, preparations containing inorganic bismuth salts used for chronic gastrointestinal disorders. Oral exposure is the most clinically relevant route in reported cases of neurotoxicity.

It can present with psychiatric features such as depression, anxiety, irritability, insomnia, impaired concentration, cognitive impairment, and personality or behavioural change. Psychotic symptoms, including hallucinations and other psychotic phenomena, have also been reported, although these appear to be uncommon and the available literature does not consistently establish to what extent they occur outside the context of delirium.

Other characteristic features include a subacute encephalopathy with confusion, ataxia, dysarthria, gait disturbance, myoclonus, tremor, impaired coordination, and, in severe cases, seizures or coma. Peripheral neurological manifestations may also occur. Other systemic manifestations include gingivitis, stomatitis, and oral discoloration.

From a multisystemic lens perspective, clinical features in other body systems include (but are not limited to):

• Gastrointestinal: Nausea, vomiting, abdominal discomfort, diarrhea or constipation, particularly with excessive or prolonged oral exposure.

• Renal/electrolytes: Renal tubular injury, proteinuria and, with more substantial toxicity, acute kidney injury.

Early diagnosis is important because bismuth poisoning can cause severe and potentially reversible neurotoxicity, including encephalopathy, myoclonus, seizures, and coma. Prompt recognition allows discontinuation of the bismuth-containing product, appropriate toxicologic assessment, and supportive management; neurological recovery may occur over weeks to months after exposure is stopped.