A review of frequently used Kampo prescriptions. Part 3. Yokukansan

Abstract Background The source of yokukansan (YKS) is thought to be Baoying‐Jinjiang (Hoeikinkyōroku in Japanese) by Xue Ji. YKS was originally designed for children and indicated for spasms, clenching of teeth, digestive dysfunction due to mental instability, and insomnia. Key Findings YKS formula consists of seven types of crude drugs. Clinical studies have revealed that YKS exerts physiological effects including the treatment of behavioral and psychiatric symptoms of dementia (BPSD), preoperative sedation and anxiety, and postoperative delirium. A meta‐analysis showed that YKS could improve BPSD and daily living activities; however, no improvement in cognitive function was observed. Preclinical studies have also reported that YKS modulates neuronal pathways in the central nervous system, including the serotonergic, glutamatergic, GABAergic, and other neurotransmitter pathways. The incidence of adverse events associated with YKS was 5.17%, with the major adverse effect being pseudoaldosteronism. Routine blood sampling is considered for hypokalemia prevention. Conclusion YKS is useful for BPSD and perioperative mental instability. The modulation of the serotonergic and glutamatergic neural pathways is one of mechanisms. Pseudoaldosteronism is one of the side effects.