Abstract

Rasayana is a specialized branch of Ayurveda aimed at promoting longevity, immunity, intellect, and tissue rejuvenation. The foundational exposition of rasayana is found in Charaka Samhita, where it is systematically elaborated under Chikitsa Sthana (1). Subsequent classical texts such as Sushruta Samhita and Ashtanga Hridaya expanded and modified its conceptual and therapeutic dimensions (2,3). However, a structured comparative analysis of its evolution remains limited. Objective: To critically analyze the evolution of the rasayana concept from Charaka Samhita to Ashtanga Hridaya, highlighting textual, philosophical, and therapeutic developments. Methods: A systematic review was conducted following PRISMA 2020 guidelines (4). Primary classical texts were analyzed with chapter and verse references. Secondary sources were retrieved from PubMed, Scopus, Google Scholar, and AYUSH Research Portal up to December 2025. Comparative textual synthesis was performed. Results: The analysis demonstrates a conceptual progression from primarily rejuvenative and longevity-focused therapy in Charaka (1) to surgical relevance in Sushruta (2) and a more concise, clinically applicable framework in Ashtanga Hridaya (3). Expansion in classification, indications, and practical formulations is evident. Conclusion: The rasayana concept evolved from a primarily longevity-focused doctrine in Charaka to a clinically systematized and therapeutically integrated framework in Ashtanga Hridaya, reflecting adaptive textual refinement across classical Ayurveda. Keywords: Rasayana, Charaka Samhita, Ashtanga Hridaya, Rejuvenation, Immunomodulation, Ayurvedic pharmaceutics