DOI: https://doi.org/10.36347/sasjm.2026.v12i09.032

Pages: 1001-1004

Background. Olanzapine-associated neutropenia is rare but potentially serious and is less widely recognized than clozapine-associated neutropenia. Routine hematological monitoring is not required for every patient receiving olanzapine. Case presentation. A 27-year-old woman with no known hematological history was admitted with cannabis-induced psychotic disorder after a suicide attempt by jumping from a height in a delusional context. A complete blood count obtained four months earlier showed an absolute neutrophil count (ANC) of 1,550/mm³. Olanzapine 10 mg/day had been started approximately two weeks before admission. On July 22, 2026, an increase to 20 mg/day was prescribed before laboratory results became available; the ANC was subsequently found to be 900/mm³. It reached a nadir of 700/mm³ on July 24, prompting permanent discontinuation of olanzapine. The patient remained afebrile and had no clinical signs of infection. C-reactive protein was negative, and peripheral blood smear, vitamin B12, folate, renal, liver, thyroid, HIV, hepatitis B, hepatitis C, and syphilis testing did not disclose an alternative cause. Aripiprazole was started at 15 mg/day on July 26 and increased to 30 mg/day on August 3. The ANC recovered to 1,950/mm³ by July 31 and remained normal at outpatient follow-up on August 17 (1,947/mm³). Conclusion. The temporal relationship, negative etiological work-up, and recovery after withdrawal constitute a positive dechallenge and support a probable association between olanzapine and neutropenia. Baseline blood counts and targeted early monitoring should be considered in patients with low or borderline pretreatment leukocyte or neutrophil counts.