Tapentadol was developed from tramadol by reducing its inhibitory effects on serotonin reuptake. In the present study, tapentadol was administered to a 49-year-old female esophageal cancer patient receiving a selective serotonin reuptake inhibitor (SSRI). On the day of administration, akathisia, nausea, dizziness, and insomnia developed. On the following day, she was diagnosed with serotonin syndrome, accompanied by fever, perspiration, myoclonic jerks mainly affecting the upper limbs, tremor of the extremities, and tachycardia. The diagnosis was made using three criteria. The symptoms disappeared immediately after discontinuation of tapentadol administration and initiation of benzodiazepine treatment. In Japan, tapentadol is an opioid analgesic for cancer pain management. If it is combined with an antidepressant, follow-up care is needed in consideration of serotonin syndrome.

High-flow nasal cannula oxygen therapy (HFNC) in palliative care is mentioned in several guidelines, however, the indication for this procedure has not been established yet. At our department, HFNC has increasingly been adopted for end-stage cancer patients when their dyspnea needs to be alleviated. This is a case report on three patients treated with this procedure at our department. Although they had severe dyspnea with respiratory failure, their daily activities, such as enjoying meals and conversation with their families, were improved with HFNC. It can be a treatment of choice to maintain and improve patients’ quality of life (QOL) in palliative setting, where benefits and risks should be considered for each patient.