Bridging 400 Years of Empirical and Scientific Evidence for Regulatory Assessments: A Systematic Appraisal of Arnica montana Using the Pragmatic Historical Assessment (PHA) Tool.

INTRODUCTION: This case study on Arnica montana applies the newly developed Pragmatic Historical Assessment (PHA) tool to systematically collate and evaluate nearly 400 years of pharmacological and pharmaceutical evidence. By sourcing data from qualified historical and contemporary bibliographic records, the study addresses a critical gap: the lack of a clear methodology for compiling and assessing evidence of traditional use, which currently hampers approvals for indications, plant parts, and posology of traditional herbal medicines within European regulatory frameworks. METHODS: Data acquisition and triangulation involved four steps: (1) selecting representative sources from three key categories-historical and contemporary medical textbooks by senior clinicians, pharmacopoeial commentaries, and contemporary herbal monographs; (2) applying a coding framework to organise data into a structured matrix for longitudinal analysis of indications, plant parts, preparations, dosages and safety observations; (3) analysing the emergence, persistence, or disappearance of therapeutic uses across historical periods and evidence streams; and (4) triangulating these qualitative data with modern scientific evidence and clinical trials. RESULTS: The convergence of the principal indications of Arnica montana across all bibliographic (qualitative) and scientific (quantitative) evidence streams over ∼400 years indicates that the German-language professional materia medica constitutes a reliable and verifiable record of medicinal plant use. The intergenerational consistency and historical continuity relate to injury recovery (i.e., in modern terms, sprains and strains, torn muscles and ligaments, bruises, oedema, and haematoma), injury-related pain management, and dermatological applications, supporting the validity of longstanding empirical medical knowledge. While similar continuity was observed for internal use of Arnica with low-dose preparations in trauma care, cardiovascular stimulation, infections, and inflammatory conditions, this was disrupted by the 1984 German Commission E decision to restrict all internal use. Most contemporary clinical trials focused on topical applications (e.g., bruises, arthritis, and musculoskeletal injuries and pain) and generally reported positive outcomes, especially when aligned with traditional use parameters. CONCLUSIONS: The Arnica case study demonstrates that the PHA tool reliably identifies consistent therapeutic indications, plant parts, posology and safety profiles from the professional materia medica. Triangulation with current regulatory literature and scientific studies confirms the verifiability of long-standing empirical medical knowledge, providing a practical framework for evidence-based assessment of traditional herbal uses. By systematically integrating the professional materia medica as an additional evidence source, the PHA broadens the evidentiary base for herbal therapeutics in Traditional European Medicine (TEM) and supports pragmatic approval assessment in European regulatory systems, thereby facilitating formal patient access to a wider range of traditional plant medicines. Further research is required to assess the tool's robustness across more medicinal plants, medical traditions, and cultural contexts.