Allergic reactions in dental practice have been a serious problem, causing various clinical symptoms and having a significant impact on the quality of dental care. This study examined various aspects of allergic reactions, their causes, mechanisms of development, and prevalence in dental practice. The purpose of the study was to conduct a comprehensive analysis of allergic reactions, their classification, clinical manifestations, and mechanisms of development, and to identify the most common causes of such reactions. To achieve this goal, a systematic literature review was conducted. As a result of the study, different types of allergic reactions and mechanisms of their development were identified. Among them, special attention was paid to immediate hypersensitivity reactions mediated by immunoglobulin E (IgE). Delayed-type reactions mediated by sensitised T lymphocytes were also considered. Pseudoallergic reactions occupied a separate place in the classification of allergic reactions. The study emphasised the importance of cross-reactions, in which several structurally similar molecules bind to the same IgE antibodies or T lymphocytes. The main results of the study showed that allergic reactions can be triggered by a variety of allergens. Prominent among these were local anaesthetics such as lidocaine and benzocaine, antibiotics including penicillins and cephalosporins, latex products such as gloves and cofferdams, acrylic materials used in dental prostheses and fillings, and metal alloys containing nickel, chromium, and cobalt. The study has contributed to a better understanding of the factors causing allergic reactions in dental practice and the mechanisms of their development. This is important for improving the diagnosis and management of such cases, thereby improving the quality of dental care provided.