Yashada Bhasma: A Comprehensive Review of Preparation Methods, Properties and Therapeutic Potential

Yashada (Jasada; zinc) occupies a distinctive place in Rasashastra, the Indian alchemical-pharmaceutical tradition. It is classified among the metals (dhatu) and, in some classifications, among the Sadharana or Puti-loha class alongside Naga (lead) and Vanga (tin). Its calcined form, Yashada Bhasma, has been used for centuries for Netra roga (eye disorders), Prameha (urinary and metabolic disorders including diabetes mellitus), Kushtha (skin disease), Pandu (anemia), Vrana (wounds) and Kasa-Shwasa (respiratory disorders). This review draws on classical Ayurvedic literature, pharmaceutical descriptions and modern physicochemical and pharmacological studies. It examines the historical background, source and classification, purification (Shodhana), incineration (Marana), quality assessment (Bhasma Pariksha), Ayurvedic pharmacodynamics, physicochemical profile, therapeutic applications and safety. Available evidence suggests that Yashada Bhasma is chiefly nanocrystalline zinc oxide (ZnO) with organic residues from herbal media, and that its biological activity may relate to bioavailable zinc. It also suggests that classical processing may improve biocompatibility. However, much of the literature is preclinical, and methodological heterogeneity, small clinical studies and safety concerns limit firm conclusions. Standardized protocols, rigorous toxicological evaluation and well-designed clinical trials are needed.