Objective: This study aimed to evaluate the effectiveness and safety profile of allopurinol in Songklanagarind hospital, Thailand. Material and Methods: Electronic medical records (EMRs) of patients having undergone allopurinol treatment for gouty arthritis, or other pertinent indications, were retrospectively reviewed. The primary outcome of this study was the longitudinal measurement of uric acid levels. A linear mixed model (LMM) analysis assessed the statistical significance of uric acid reduction across hospital visits. The safety profile regarding allopurinol-related adverse drug reactions was assessed.Results: A total of 11,277 EMRs were extracted, of which 8,801 EMRs were eligible for further analyses. These records pertain to a cohort of 3,219 unique patients whose visits were arranged chronologically from the earliest to the fifth recorded visit. Overall, uric acid level decreased after allopurinol treatment in all patients. Across subsequent visits, the analysis, using LMM, found a significant reduction in uric acid levels (χ²=1465.4, df=4, p-value<0.001), with the early reduction observed as early as the second visit. The incidence of allopurinol-related adverse reactions was 4.37% (385/8801 cases). Conclusion: The current dosing regimen of allopurinol at Songklanagarind Hospital has demonstrated favorable treatment outcomes and continues to be effective. This data provides insights into pharmacological management and its real-world outcomes.