AbstractObjectiveControlling hyperactive and mixed delirium is extremely important for the continuation of cancer treatment in palliative care. In general, oral antipsychotics are the first-line drug therapy for delirium; however, oral administration is problematic in patients presenting dysphagia. In this case report, we describe an end-stage cancer patient with aphagia who developed delirium and responded to sublingual antipsychotic asenapine for treating delirium. We also discuss the effectiveness of asenapine in hyperactive delirium as well as its usefulness for treating delirium in palliative care.MethodA cancer patient with delirium was treated with several oral antipsychotics commonly used to treat delirium but did not respond to any of them. The patient subsequently developed aphagia with progression of the disease. Sublingual asenapine was therefore given to treat delirium.ResultAsenapine was effective in treating delirium without causing any obvious side effects.Significance of resultsIn the present case, asenapine was effective in treating hyperactive delirium that did not respond to commonly used antipsychotics. Because asenapine is a sublingual tablet, it can be used in patients with dysphagia and aphagia. In addition, this drug is anticipated to diminish the burden of end-stage patients from taking oral medications. Furthermore, its management is easier compared with injections, and can therefore also be easily used in homecare patients. Based on these perspectives, asenapine may become an important option for treating delirium in palliative care.