The tradition of Herbal Medicine is based on observation and experience handed down through the generations. This is now complemented by an enormous body of scientific scrutiny which assists practitioners in applying remedies in the safest, most efficacious manner.
Herbal medicines contain a huge array of constituents which affect the human system (‘phyto’ or plant chemicals). This seems to confer a measure of safety with their ingestion, so minimizing side effects, which is an huge issue with modern pharmaceuticals. Of course, some of the most toxic products around are also in plants, like the alkaloids in hemlock for instance. Thus the need for extensive knowledge is required for best/safe practice. See www.nhaa.org.au “What is Herbal Medicine” (National Herbalists Association of Australia)