Medicinal plants have been known since the beginning of mankind. In recent years, and as a result of the increasing interest that alternative therapies have created in the population, their use has increased considerably. The "natural" effect that preparations of a vegetal origin are given, prevent the user from assessing the possible adverse effects derived from their consumption or their potential interactions with drugs. Moreover, the legislation currently in force allows for the approval of compounds made out of medicinal plants by means of a simplified procedure that does not provide sufficient data on the pharmacological effects of the product, which makes the situation even worse. The assessment on the consumption of medicinal herbs and their registry in the medical history are basic actions at the time of appraising any adverse effects or any interactions with standard drugs, which have to be mandatorily notified to the Farmacovigilance Centres.