This chapter investigates the histopathological characteristics and complications associated with the use of biopolymers as aesthetic fillers. Biopolymers are frequently injected into various anatomical sites, presenting significant health risks, including severe adverse reactions such as granulomas, chronic inflammation, and autoimmune conditions, notably autoimmune syndrome induced by adjuvants (ASIA) syndrome. The inherent lack of biocompatibility and the potential for the migration of these substances further complicate local and systemic health outcomes. Clinical manifestations of these complications include pain, inflammation, and, in severe instances, pulmonary embolism and tissue necrosis. The findings highlight the essential role of histopathological evaluation in elucidating tissue responses and identifying long-term complications associated with biopolymer injections.