The serotonin syndrome and psychosis-like side-effects of fluvoxamine in clinical use – an estimation of incidence

Abstract

Objective: The incidence of the serotonin syndrome or serotonin-syndrome-like side effects during treatment with the selective serotonin reuptake inhibitor (SSRI) fluvoxamine should be evaluated. Method: 200 inpatients treated for the first time with fluvoxamine were prospectively evaluated for the occurrence of a serotonin syndrome over a period of 8200 treatment days. Retrospective follow-up data of outpatient treatment covered 8891 days. Results: No full-blown serotonin syndrome occurred, but 3 patients developed a reversible change of mental status with insomnia, agitation, confusion and incoherent thoughts without other symptoms of the serotonin syndrome. Conclusions: It is concluded that the occurrence of a potentially lethal serotonin syndrome is rare in fluvoxamine treatment, but psychosis-like syndromes as a side effect of serotonergic stimulation might occur. In the investigated sample the rate was 0.006–0.04 per 100 treatment days.