Partial ordering of undesirable effects reported for traditionally used medicinal herbal substances

According to the World Health Organization, the safety of herbal medicines has become a major concern to both national health authorities and the general public. Here, using partial order analysis, we explore the reported undesirable effects of medicinal herbal substances, in their traditional/ethnopharmacological use. Data were retrieved from the European Union list of herbal substances for use in traditional medicinal products and the final European Union herbal monographs of the European Medicines Agency. Our analysis revealed that the attributes (reported to undesirable effects) of the poset with the highest sensitivity were (in diminishing order) the gastrointestinal disorders, allergic skin reactions, allergic reactions and hypersensitivity reactions. Variation in undesirable effects of herbal substances between major phylogenetic groups of origin plants was also recorded and an overall arrangement of medicinal herbal substances in a rank order was achieved. This classification may serve as a guide for decision-making process for both healthcare providers and consumers.