Safety of herbal decoctions: A scoping review of clinical studies in South Korea focusing on liver and kidney functions

Ethnopharmacological relevance: Approximately 27% of individuals seeking Korean medicine (KM) services in South Korea are prescribed herbal decoctions. The South Korean government has considered the validity of providing National Health Insurance coverage for herbal decoctions. Therefore, it is important to investigate their safety. Aim of the study: To investigate the safety of herbal decoctions commonly prescribed by KM doctors and to assess their effects on liver and kidney function by comprehensively analyzing Korean clinical studies in a scoping review. Materials and methods: The Arksey and O'Malley framework and modified methods were applied in this scoping review. A comprehensive search of seven electronic health databases was conducted, and relevant clinical studies published between 2000 and 2022 were identified. Subsequently, only clinical studies reporting the results of liver and/or renal function tests in patient prescribed herbal decoctions by KM doctors were included. The characteristics of the included clinical studies and the reported proportion of each liver and/or renal function indicator were analyzed. Meta-analyses of the effects of herbal decoction on liver and/or renal function reported in prospective cohort studies were also performed. Results: Fifty-nine clinical studies were included in this review. The proportion of prospective cohort studies markedly decreased in the 2010s compared to the 2000s, while there was no noticeable change in the number of relevant clinical studies. Herbal decoctions were prescribed for less than one month in most included studies. Abnormal changes in liver or renal function indicators were identified in a small number of studies (3.70% and 7.69%, respectively). In a meta-analysis of 15 prospective cohort studies, no statistically significant changes in four liver function indices and two renal function indices were observed before and after the prescription of herbal decoctions. Conclusions: Qualitative and quantitative analyses demonstrated favorable safety profiles for herbal decoctions. This scoping review includes the gaps noted between clinical application and research regarding the safety profiles of herbal decoctions. These findings could be used as evidence to support the inclusion of herbal decoction prescriptions in the National Health Insurance coverage in South Korea.