Delirium during fluoxetine treatment. A case report.

The correlation between high serum tricyclic antidepressant concentrations and central nervous system side effects has been well established. Only a few reports exist, however, on the relationship between the serum concentrations of selective serotonin reuptake inhibitors (SSRIs) and their toxic effects. In some cases, a high serum concentration of citalopram (> 600 nmol/L) in elderly patients has been associated with increased somnolence and movement difficulties. Widespread cognitive disorders, such as delirium, have not been previously linked with high blood levels of SSRIs. In this report, we describe a patient with acute hyperkinetic delirium connected with a high serum total fluoxetine (fluoxetine plus desmethylfluoxetine) concentration.