In recent decades, the pharmacological properties of numerous medicinal plants and opportunities in phytotherapy have been explored through research projects, reviews, and monographs. These studies confirm that medicinal plants offer new approaches to tackling diseases. However, improvement of phytotherapy in clinical practice relies on a number of critical factors. In particular, the studies are very heterogeneous, and results and their interpretation by healthcare workers vary greatly, so preventing consistency in clinical practice. There is therefore a lost opportunity to improve phytotherapy practice, because the work being done and the related systematic reviews cannot act as a body of data on which to base clear clinical recommendations. Approaches such as the Grading of Recommendations Assessment, Development and Evaluation or the Scottish Intercollegiate Guidelines Network methodology could easily help standardise the use of phytotherapy in clinical practice. In this context, evidence-based phytotherapy guidelines could offer new healthcare approaches to the treatment of diseases.