Herb–drug interactions with clinical impact: A systematic review of global clinical evidence on medicinal plants widely used in Ecuador

Ethnopharmacological relevance: The widespread use of medicinal plants in Ecuador increases the risk of herb-drug interactions, many of which may compromise patient safety. Understanding clinically relevant interactions is essential for preventing adverse events and guiding evidence-based decision-making. Aim of the study: To systematically analyze the clinical evidence on interactions between medicinal plants commonly used in Ecuador and conventional medications, identifying their mechanisms and potential therapeutic risks. Materials and methods: A systematic review was conducted following PRISMA 2020 guidelines. Articles published between 2015 and 2025 were retrieved from major scientific databases. Studies involving humans and reporting herb-drug interactions were included. Studies conducted worldwide involving medicinal plants commonly used in Ecuador were considered. Methodological quality was assessed using predefined indicators, and interactions were classified according to the Janusmed clinical interaction severity scale. Results: Out of 102 records, 47 studies met inclusion criteria. Among these, 31.9% reported clinically relevant interactions. The most frequent consequences were reduced plasma drug levels (40%), increased risk of bleeding (13.3%), decreased efficacy of immunotherapy (13.3%), and hepatotoxic or endocrine effects. The most frequently implicated plants were Camellia sinensis L., Hypericum perforatum L., Borago officinalis, and Glycyrrhiza glabra L. Conclusions: Clinically significant herb-drug interactions are common among medicinal plants widely used in Ecuador and may affect therapeutic efficacy or increase adverse effects. Greater awareness among healthcare professionals is essential to improve patient safety and prevent harmful combinations.