Safety monitoring of herb-drug interactions: a component of pharmacovigilance

Adverse drug reactions, including those resulting from interactions between herbal medicines and conventional drugs, are a public health problem worldwide. The need for pharmacovigilance for herb-drug interactions (HDIs) is essential for the identification and assessment of risks of using herbal products (questionable safety, efficacy and quality), which are not always tested with rigor, or often not subject to approval by regulatory agencies. Spontaneous and active surveillance conducted by national pharmacovigilance centres permits a rapid detection of potentially harmful combinations of products. The incidence and prevalence of HDIs are difficult to predict because of the underreporting of adverse effects. It is important for health professionals, consumers, regulatory authorities and suppliers of herbal medicines to be aware of the possible adverse effects and drug interactions caused when herbal medicines are co-administered with conventional drugs. National pharmacovigilance centres continue to play a significant role in increasing awareness of drug safety, in this case with HDIs. The authors' objective for this paper is to provide awareness among policy makers responsible for the design of appropriate pharmacovigilance practices and therefore to highlight the importance of pharmacovigilance in the safety monitoring of HDIs.