Background: The incidence of a disease can help health professionals to identify risk factors and health-care policymakers to develop corresponding policies. The realization of both purposes depends on comprehensive studies, especially studies done on a large scale. However, comprehensive studies on the incidence of anaphylaxis among inpatients in China are still notably scarce. Hence we aim to explore the incidence and clinical characteristics of anaphylaxis among inpatients over a 21-year span in Wuhan, China. Methods: We retrieved data on anaphylaxis cases from the Data Platform Application Portal (DPAP) across three medical centers of Tongji Hospital, Wuhan, China from January 1, 2003, to December 31, 2023. Results: The data encompassed a total of 362 anaphylaxis patients from 2,139,272 inpatients. Among them 204 (56.4%) were male, and the median age was 45 years old. Over the past two decades, the incidence rate of anaphylaxis at Tongji Hospital was 16.92 per 100,000 individuals. After adjusting for gender and age, the annual standardized incidence rate was 234.53 per 100,000 individuals. The incidence rate of anaphylaxis among the inpatients revealed a relatively stable but slowly rising trend over the 21-year observation period. As for the triggers of anaphylaxis, drugs were responsible for 73.6% of triggers, with antibiotics accounting for the majority of these cases (38.4%). Drug triggers also showed age-specific features: chemotherapy (17.9%) had the highest proportions among children aged 0-3 years; blood products were more prevalent in school-age children. 13.5% of the cases had an unknown cause. In anaphylaxis cases, despite that only 36.0% received epinephrine treatment, the application of epinephrine still showed an ascending trend. Moreover, the mortality rate for anaphylaxis was relatively low (1.6%), displaying a consistent downward trend. Conclusion: Our study provides insights into the incidence of anaphylaxis among inpatients in Wuhan over a 21-year period. Drugs are the most common triggers for anaphylaxis, and the use of epinephrine in anaphylaxis management is far from optimal.