Overview of Adverse Reactions of Radiopharmaceuticals.

Aims: Theranostics utilizes the nuclear properties of radioactive isotopes, especially for molecular imaging and targeted therapy. Radiopharmaceuticals (RPs), which combine a pharmaceutical ligand with a radionuclide, enable accurate diagnosis and treatment of various diseases through modalities such as PET and SPECT imaging. The aim of this papare is to review adverse reactions associated with diagnostic and therapeutic radiopharmaceuticals, with an emphasis on their severity and clinical management.

Materials and methods: This review evaluates documented adverse effects (AEs) related to RPs used in nuclear medicine imaging (PET and SPECT) and radionuclide therapy, focusing on their severity and clinical management strategies. It also considers the mechanisms of RPs toxicity, distinguishes between general and specific AEs, and highlights the limitations in current adverse drug reaction (ADR) assessment tools. The methodology used was the research and synthesis of most relevant published literature data; most relevant papers were synthesized regarding the reporting system of ARs and categorized by the specific and systemic adverse effects of RPs.

Results: Side effects from diagnostic RPs are relatively rare and typically minimal. Therapeutic RPs, selected for their high-energy radiation properties, can cause DNA damage to malignant cells while minimizing harm to healthy tissues. Although adverse effects do occur, they are generally fewer and less severe compared to conventional therapies. Severe toxicity is rare and often preventable. Both patient- and provider-reported ADRs offer important safety insights, though validated assessment instruments remain limited.

Conclusion: Radionuclide therapy offers a targeted approach that is a less invasive alternative to conventional treatments with a favorable safety profile. Continued evaluation of adverse reactions and the development of standardized ADR assessment tools are essential for improving patient outcomes and RP safety monitoring.