[Interaction between medicines and medicinal plants]

In recent years there has been a notable increase in the consumption of medicinal plants in Spanish society. This might be due to the fact that in some cases they have shown themselves to be efficient in treating certain pathologies and to the erroneous perception that these products are innocuous. Medicinal plants behave as authentic medicines since the chemical substances of which they are formed can have a biological activity in humans. For this reason, their joint administration with "conventional medicines" can produce variations in the magnitude of the effect. This type of interaction, just like those produced between two or more medicines, can produce pharmacokinetic mechanisms if they affect the processes of absorption, distribution, metabolism and excretion, or pharmacodynamic mechanisms if they affect the result of the pharmacological action. In the medical literature there are few articles and notifications of cases concerning the adverse effects and interactions that affect medicinal plants, which probably reflects an under-notification of these phenomena. If we add to this the lack of experimental data and controlled studies, perception of their prevalence is difficult or nearly impossible. This article sets out, in an order that will be explained later, the findings of an exhaustive review of the medical literature with the aim of making its existence known to the reader, without going into other considerations, such as the degree of evidence for example, which will be the subject of forthcoming articles.