Oral Hydration Reduces Hypersensitivity Reactions to Iopamidol in CT Angiography: A Retrospective Cohort Study on Optimal Timing

Abstract Objective To evaluate if oral hydration prevents hypersensitivity reactions to Iopamidol during CT Angiography (CTA) and to identify the optimal drinking time. Methods We reviewed 7,655 CTA cases (Dec 2023–July 2025). Patients were divided into a non-hydration Control group and three Oral Hydration subgroups who drank 500mL of water at 10, 20, or 30 minutes before the scan. We compared reaction rates and severity. Results The overall reaction rate was 0.22% (17/7,655). Hydration significantly lowered the reaction rate compared to controls (0.19% vs. 0.31%, P < 0.05). The 30-minute subgroup had the lowest incidence (0.15%). Crucially, no severe (Grade III) reactions occurred in hydrated patients, whereas the control group had one severe case. Conclusion Drinking 500mL of water 30 minutes before CTA is a simple, effective nursing intervention that reduces allergic reactions and may eliminate severe adverse events.