Case report of eosinophilia induced by quetiapine

An increase in the concentration of eosinophils in blood may lead to endocarditis, myocarditis, and pericarditis. When the absolute eosinophil count increases beyond 1.5 x 10(9)/L, myocardial damage and even death can occur. This case report describes a 47-year-old male with an alcohol-induced psychotic disorder who developed eosinophilia 4 weeks after starting treatment with quetiapine 50-200 mg/d. His maximum recorded absolute eosinophil count was 7.63 x 10(9)/L (normal range < 0.5 x 10(9)/L), but the level returned to normal over a 4-week period after stopping quetiapine and no myocardial damage was observed. This patient's dramatic eosinophilia did not have any associated clinical symptoms; it was only identified as part of a routine blood test a few weeks after starting quetiapine. This is a reminder that all clinicians who treat patients with antipsychotic medications must be vigilant about the occurrence of such rare but life-threatening adverse events.