Recurrent Cholinergic Crisis Caused by Therapeutic-Dose Rivastigmine Patch in an Elderly Patient With Alzheimer's Disease: A Case Report.

Cholinesterase inhibitors (ChEIs) are widely used for the treatment of dementia and other conditions, but may rarely cause cholinergic crisis, a potentially life-threatening complication. We report an elderly female patient with Alzheimer's disease who experienced three episodes of cholinergic crisis over 32 months while receiving a therapeutic dose of transdermal rivastigmine (18 mg/day). Each episode involved vomiting, diarrhea, diaphoresis, and neurological symptoms, with marked reductions in serum cholinesterase levels (53-63 U/L at presentation). During the first two episodes, alternative diagnoses such as acute gastroenteritis and possible pesticide exposure were initially suspected, and cholinergic crisis secondary to rivastigmine was not recognized. After the third episode, rivastigmine was permanently discontinued, resulting in the complete resolution of both acute and chronic mild gastrointestinal and autonomic symptoms. This case highlights the diagnostic challenges of cholinergic crisis in elderly patients receiving ChEIs and underscores the importance of considering this condition when unexplained gastrointestinal or autonomic symptoms occur even during standard therapeutic dosing.