Paliperidone induced neutropenia in first episode psychosis: a case report.

Background: Neutropenia, a decrease in total number of neutrophils below 1500/mm and particularly severe neutropenia, defined as neutrophils less than 500/mm, is a potential adverse effect of antipsychotic medications that can lead to increased risk of infections and death. However, much of the attention on the potential adverse effect is centered exclusively on clozapine, which remains the only antipsychotic medication in the United States requiring standardized monitoring of blood work. We demonstrate here that paliperidone can also cause neutropenia and therefore clinicians should be aware of this possibility especially during initiation of treatment.