Toxicology of Herbal Medicines

Abstract

The use of herbal medicines dates back many centuries, and even today, 90% of the world’s population relies upon herbal medicines for their healthcare needs. The major problem regarding herbal medicines is the lack of standardisation of their constituents among different products. The type and concentration of constituents in a plant species may vary in different regions of the world, and even in different time zones in the same region depending on the prevailing climate conditions, soil and so forth. The major difference between traditionally used herbal medicines and ‘modern drugs’ is that the latter are purified active compounds, whereas the former are almost always mixtures of constituents from a whole or a piece of a plant. Furthermore, drugs are assessed in a much more detailed and intensive manner; once a drug is approved, there are sufficient data to assess its safety, whereas data on traditional herbal medicines are usually insufficient to draw satisfactory conclusions on their safety profiles. Therefore, acute or chronic poisonings and even deaths can occur due to uncontrolled use of herbal medicines all over the world. Furthermore, the assumption that ‘natural’ is not hazardous has led to a bias in using herbal medicines in society and has made the situation more complicated. Common scientific sense strongly suggests that herbal medicines should be considered as clinical drugs in terms of identifying their safety profile by means of toxicity testing. In this chapter, the health impact of herbal medicines is classified under four main headings: history and regulation, traditional and clinical use and pharmacological/toxicological effects, interactions with other herbs and prescription drugs and intentional and unintentional adulteration.