[A case of severe hypokalemia caused by a Chinese herbal remedy (Yokukansan) in an 81-year-old woman with dementia].

An 81-year-old woman had been visiting 2 hospitals for hypertension and dementia, prior to admission to our emergency room for nausea, hypertension, severe hypokalemia (K 1.29 mEq/l) and abnormal electrocardiography findings. She had been taking a Chinese herbal remedy (Yokukansan, 7.5 g/day) for the behavioral and psychological symptoms of dementia (BPSD) for 6 months before admission. On admission, she presented with metabolic alkalosis with hypokalemia, a high urinary excretion of potassium, low plasma rennin activity and hypoaldosteronism. We diagnosed pseudoaldosteronism caused by the Chinese herbal remedy Yokukansan (which includes licorice). Discontinuation of Yokukansan and the administration of potassium supplements normalized her serum potassium level within 2 weeks. However, we could not successfully control her BPSD by drugs such as tiapride hydrochloride or risperidone. BPSD is a serious problem in an aging society, with the ever-increasing incidence of dementia. The use of Yokukansan has recently been receiving attention as a new treatment modality for BPSD. Because this agent has relatively few adverse effects compared with typical antipsychotic agents, the use of Yokukansan is continuing to increase sharply. Pseudoaldosteronism, if caused by Yokukansan, may cause death by severe hypokalemia, but the early identification of hypokalemia is sometimes difficult because drug-induced hypokalemia is not dose-dependent. We think it is important to create awareness of the possible adverse effects of Yokukansan, such as hypertension and electrolyte abnormalities to make the most of this commonly used drug for the treatment of BPSD among dementia patients.