Priapism After Initiation of Long-Acting Injectable Risperidone: A Case Report.

Priapism is an uncommon but serious urological emergency, defined as a persistent penile erection unrelated to sexual stimulation. If not promptly treated, it carries a significant risk of permanent erectile dysfunction. Among pharmacologically induced causes, antipsychotic medications are frequently implicated. We describe the case of an 18-year-old male diagnosed with cannabis-induced psychosis who developed acute ischemic priapism within 24 hours of receiving his first dose of long-acting injectable risperidone. The patient required urgent urological management, which resulted in complete resolution of the episode. Risperidone was subsequently discontinued, and treatment was switched to olanzapine, gradually titrated to 10 mg/day. This change was associated with full remission of psychotic symptoms, without recurrence of priapism. This case underscores the importance of early recognition of priapism, careful antipsychotic selection, and patient counseling, particularly when initiating long-acting injectable formulations.