Rasashastra is the branch of Ayurvedic pharmaceutics concerned with processing metals, minerals, and poisonous substances — grouped as Maharasa, Uparasa, Sadharana rasa, and Dhatus — into a form fit for internal administration, known as Bhasma. The nano-sized particles of Bhasma increase surface area, enhance bio-solubility, and improve the rate of dissolution and bioavailability, allowing quick therapeutic results at a comparatively lower dose. Preparation of Bhasma involves classical pharmaceutical procedures such as Shodhana and Marana, and occasionally Amriteekarana and Lohiteekarana, followed by the confirmatory tests (Siddha Pareeksha) described in the classics. A Bhasma that fails these tests is termed Apakva Bhasma, and its consumption can lead to Adverse Drug Reactions (ADR). This review compiles information from classical Ayurvedic textbooks and published research articles to document the Apakva Bhasma Sevana Doshas — the classically described adverse effects of improperly processed Bhasma — for major Bhasmas including Abhraka, Swarna Makshika, Haratala, Manahshila, Rajata, Lauha, Vanga, Naga, and Yashada, along with their classically prescribed management (Cikitsa). Findings from modern toxicity studies on several of these Bhasmas are also reviewed. Standardisation of raw-material selection, Shodhana, Marana, and adherence to the Siddha Lakshanas and Siddha Pareekshas at every stage are essential to ensure the safety of Bhasma preparations. Since the Siddha Pareeksha of dispensed medicines is not routinely performed by the prescribing physician, awareness of the symptoms of Apakva Bhasma Sevana and their management remains essential for safe clinical practice.