Acute Onset Orolingual Choreoathetosis and Auditory Hallucinations in a Healthy Young Adult Following High Melatonin Dose.

Melatonin is considered a safe OTC sleep aid with rarely reported adverse effects despite limited data. We present a case of acute orolingual choreoathetosis and auditory hallucinations following 132 mg ingestion of melatonin in an otherwise healthy, 22-year-old active-duty male in IBOLC training. The patient developed abrupt, predominantly orolingual choreoathetosis and mild auditory hallucinations, 1 hour after waking. Three days earlier, he began taking 24 mg of melatonin nightly for insomnia and ingested 132 mg the night before presentation. He denied alcohol, illicit drug, or other medication use. On ED arrival, he was hemodynamically stable with continuous orolingual choreoathetosis. Initial labs demonstrated mild acute kidney injury and transaminitis. Head CT was unremarkable. MRI head showed a nonspecific left frontal white matter hyperintensity. Lumbar puncture revealed normal protein and WBC, negative culture, and negative oligoclonal bands, though CSF processing difficulties prevented autoimmune panel completion. Neurologic symptoms resolved by the next morning without recurrence, and a subsequent EEG was unremarkable. This case documents a temporal association between high-dose melatonin exposure and acute neurologic symptoms but does not establish melatonin as the cause. The clinical presentation also occurred in the setting of substantial confounders, including sleep deprivation and heat exposure. This observation supports further investigation of uncommon neurologic presentations occurring after high-dose melatonin intake.