Case of delirium and convulsion after administration of olanzapine in a cancer patient with refractory vomiting

<b>Purpose:</b> We report a case of delirium and convulsion after administration of olanzapine in a cancer patient with refractory vomiting. <b>Case report:</b> The patient was a male in his 70s who suffered from lung cancer. After chemotherapy, olanzapine was used for refractory nausea and vomiting. Since this treatment, the patient has experienced delirium and convulsions. While we modified some reversible causes of the delirium, the delirium did not improve. Discontinuation of olanzapine resulted in improvement of the delirium. Recurrent convulsions did not occur with sodium valproate. Olanzapine might increase the risk of delirium and convulsions.