Toxic encephalopathy due to self-administration of over-the-counter amantadine: a case report of a patient undergoing maintenance hemodialysis and safety alert.

This report describes a 49-year-old male patient with end-stage renal disease who developed acute mania, incoherent speech, and vivid visual hallucinations after self-administering an over-the-counter cold medication containing amantadine during regular hemodialysis. Laboratory toxicology analysis confirmed toxic encephalopathy caused by significantly elevated blood amantadine levels. Following five consecutive days of combined hemoperfusion and hemodialysis for intensive clearance, the patient achieved complete resolution of neuropsychiatric symptoms. This case highlights the unique high-risk profile of chronic kidney disease (CKD) patients, particularly dialysis-dependent individuals, when engaging in self-medication. It underscores the critical importance for clinicians to proactively inquire about medication history, understand relevant pharmacokinetic alterations, and implement targeted interventions. While single-case evidence cannot drive regulatory change, this case suggests a potential safety gap in regions where amantadine remains available over-the-counter, warranting further pharmacoepidemiologic investigation.