Traditional Use Documentation and the Evidence Hierarchy

Traditional use evidence occupies a formally recognised, tiered position within herbal drug regulatory evaluation, reflecting the unique evidentiary status accorded to long-standing, well-documented human use. Citation of a formulation within a recognised classical text — such as the Charaka Samhita, Sushruta Samhita, or Ashtanga Hridayam within the Ayurvedic tradition — represents the highest tier of traditional evidence, and is generally sufficient, combined with Schedule T GMP compliance, to support marketing of a classical ASU medicine without further clinical data. Inclusion within an official pharmacopoeial monograph (the Indian Pharmacopoeia, WHO monographs, or other recognised pharmacopoeia) constitutes a second, closely related tier of recognised traditional use status. Published ethnobotanical survey data and peer-reviewed ethnopharmacological research provide a further, somewhat lower tier of supporting evidence, while post-marketing surveillance and pharmacovigilance data provide ongoing, real-world safety corroboration once a product is in clinical use. The European Union's Traditional Herbal Medicinal Products Directive requires a documented minimum of thirty years of traditional use, of which at least fifteen years must be within the European Union itself, illustrating that the specific evidentiary threshold applied to traditional use varies materially between regulatory jurisdictions even though the underlying evidence-hierarchy concept is broadly shared internationally.