We present a patient with schizophrenia who was successfully rechallenged with clozapine after discontinuation due to neutropenia. In Japan, clozapine is under-prescribed in comparison to Western countries, and very few cases of clozapine rechallenge have been reported. A 45-year-old man had been diagnosed with schizophrenia at the age of 22. After repeated relapses and hospitalizations, he was considered treatment-resistant. He was started on clozapine at the age of 37, and showed a good response. He was admitted to hospital for agitation and delusions. After admission, he developed aspiration pneumonia and consequently lost his appetite. Twenty-three days after the onset of pneumonia, decreases in white blood cells (3600 cells/mm3) and absolute neutrophil count (1370 cells/mm3) were observed, and clozapine was immediately discontinued. Subsequently, he became paranoid, aggressive, and refused to eat and take medication. After treatment with several other antipsychotics, each of which exerted a poor effect, we rechallenged the treatment with clozapine with the approval of the Expert Committee for Clozaril Patient Monitoring Service. This decision was made because the neutropenia may not have been solely due to clozapine but may have been the result of a combination of manageable factors. After re-initiation of clozapine, the patient’s mental state markedly improved, and he was eventually discharged. He remained mentally stable on clozapine for more than 2 years after the rechallenge, with no recurrence of neutropenia. When rechallenging with clozapine, it is crucial to analyze the possible alternative causes of neutropenia. Further research is required to support the applicability of clozapine rechallenge.
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