Clozapine and Pancytopenia: An Extremely Rare but Serious Hematological Adverse Event

Clozapine is widely used in treatment resistant schizophrenia. Pancytopenia, an extremely rare documented side effect of clozapine, can have grave consequences. This case report is about a 53-year-old male with schizophrenia and on clozapine for 15 years who was admitted in the general medicine department with pancytopenia. On psychiatric consultation–liaison, his clozapine was immediately stopped and pancytopenia was investigated. Causes leading such extremely low blood cells were ruled out, and an impression of clozapine-induced pancytopenia was made. Clozapine was immediately stopped and he was managed conservatively with blood transfusion, antibiotic, and hematinics. He eventually made complete recovery after 3 months and his psychotic symptoms were managed with risperidone. Based on this case of sudden and late onset pancytopenia, clinicians must remain vigilant of trends in blood counts regardless of duration and dose of clozapine to decrease the morbidity and mortality.