Levodopa-Induced Hypersalivation: A Case Report

Abstract

Levodopa combined with carbidopa is the cornerstone of symptomatic treatment for Parkinson's disease. While effective for motor symptoms, its impact on autonomic pathways can produce paradoxical reactions. We report the case of a 51-year-old male with HIV and a new diagnosis of parkinson-plus syndrome who developed acute, profuse sialorrhea shortly after initiating levodopa/carbidopa. Although his tremor, rigidity, and gait improved, significant hypersalivation emerged after five doses. A Naranjo adverse drug reaction probability score of 8 indicated a probable association. The symptom resolved completely upon discontinuation of levodopa/carbidopa and initiation of trihexyphenidyl and rasagiline. This case highlights a critical clinical paradox: sialorrhea, typically a feature of advanced Parkinson's disease due to impaired swallowing, can also be an iatrogenic and reversible effect of its primary treatment. Recognizing this potential and reversible side effect is crucial to prevent unnecessary patient discomfort and to inform appropriate treatment adjustments in parkinsonian disorders.