An Older Man with Clonus, Rigidity, Hyperreflexia, and Hand Tremors.

Serotonin toxicity (ST) is a preventable, life-threatening condition caused by serotonergic agents. It typically arises from combined drug use that affects serotonin's release and metabolism. While often presenting with mild symptoms that may be overlooked or misdiagnosed, severe toxicity is associated with significant mortality. The older population is particularly at risk due to altered drug pharmacokinetics, a tendency for multiple drug use, and symptom overlap with common neurodegenerative conditions. The case study discusses an older patient with prolonged ST developed with the use of several serotonergic drugs for postherpetic neuralgia. It emphasizes the challenges of polypharmacy in older patients, offering insights into the serotoninergic potential of multiple medicines commonly used in older adults, the pathophysiology, proper diagnosis and differential diagnoses, and management strategies of ST. Accurate diagnosis requires heightened vigilance from healthcare professionals regarding potential drug interactions and familiarity with the specific clinical criteria. Regular revision and adjustment of medications in older patients and preference for the non-pharmacological treatment of chronic pain are essential for preventing ST. This case report is a convenient way for many healthcare professionals to update their knowledge about ST, its diagnosis and management.