Adverse drug reactions in Korean herbal medicine: A prospective cohort study

IntroductionA large proportion of herbal drugs (HM) are still excluded in the regular pharmacovigilance system in Korea, despite suspicions about their safety. This study aimed to estimate the prevalence and risk factors of adverse drug reactions (ADRs) in HM and establish a foundation for a comprehensive surveillance system that includes herbal drugs.MethodsThis is a prospective cohort study based on a registry of patients who had been prescribed herbal drugs in a Korean medicine hospital. The authors monitored the registered patients and detected ADRs from HM using the WHO-UMC Causality Scale. The prevalence and possible risk factors of ADRs in HM were investigated.ResultsFrom 341 registered patients, 28 cases of adverse events (AEs) were detected and they were categorized as certain (14.3%), probable (21.4%), possible (42.9%), and unlikely (21.4%). Out of 22 ADRs, 29 cases of drug-symptom pairs were extracted. The prevalence of ADRs in HM was 9.36%. Old age was a risk factor for ADRs (OR 4.4, 95% CI, from 1.76 to 11.00) in HM. The most frequently reported clinical manifestation of ADR was dyspepsia (20.7%), followed by nausea and diarrhoea (17.2%, each). The severity of the ADRs was mostly mild (89.7%) and no serious ADR was detected.ConclusionThis study shows the possibilities and limitations of reconstructing the current pharmacovigilance system to guarantee the safe use of HM.