Tetrahydrouridine is primarily used in research and clinical settings as a potent inhibitor of cytidine deaminase, an enzyme that breaks down cytidine analogs. This property makes it valuable in enhancing the efficacy of certain chemotherapy drugs, such as cytarabine and decitabine, by preventing their degradation and prolonging their activity in the body. It is also studied in the context of improving the therapeutic outcomes of nucleoside-based treatments for cancer and viral infections. Additionally, tetrahydrouridine has shown potential in epigenetic research, where it aids in modulating DNA methylation patterns, offering insights into gene regulation and potential treatments for diseases linked to abnormal methylation.