Effect of Xiaoyaosan on major depressive disorder

BACKGROUND: This study aims to evaluate the efficacy of Xiaoyaosan (XYS) for treatment of major depressive disorder (MDD) and to review the studies on antidepressant mechanisms of XYS. METHODS: The China Knowledge Resource Integrated Database (1998–2014), VIP Journal Integration Platform (1989–2009), and PubMed (1950–2014) were used to search for and collect scientific publications related to XYS and MDD. Clinical trials for “MDD” and “xiaoyao” were screened. Papers that used the original prescription of XYS for treatment and in combination with Western medicines were included, while papers describing modified XYS were excluded. Four investigators read and screened the resulting publications independently, evaluated the associated scientific results and evidence. RESULTS: There were no conclusive results to support the efficacy of XYS for treatment of MDD, owing to limited sample sizes, flaws in blinding and randomization, and lack of multi-centered clinical trials. Among the experimental studies on the effects of XYS possible involvement of 5-hydroxytryptamine, hypothalamic–pituitary–adrenal axis function, and neuroinflammation were possibly involved demonstrated. CONCLUSIONS: The effectiveness of XYS for treatment of MDD is uncertain.