INTRODUCTION: Helicobacter pylori eradication therapy requires a complex prescribing schedule combining clarithromycin, amoxicillin, and a proton-pump inhibitor (PPI) or potassium-competitive acid blocker (P-CAB, vonoprazan). To reduce the burden of complex prescribing and increase adherence, a vonoprazan triple-drug blister pack comprising all three medications was launched in June 2016. This study aimed to assess the impact of the combination blister pack on eradication success rate in Japan immediately after launch. METHODS: We performed an interrupted time series analysis using a large administrative claims database of 7,300,000 insured individuals. We identified 36,570 patients who received first-line clarithromycin triple therapy from June 2015 to May 2016 (prelaunch) and 35,721 who received the same therapy from July 2016 to June 2017 (post-launch). The primary outcome was the success rate of clarithromycin triple therapy and the secondary outcomes were proportion of vonoprazan use and proportion of combination blister pack use. RESULTS: The success rate of clarithromycin triple therapy increased by 2.44% (95% confidence interval [CI] 1.36-3.52; P < 0.0001) after the launch of the vonoprazan triple-drug blister pack. The proportion of vonoprazan use and proportion of combination blister pack use increased by 12.7% (95% CI 10.0-15.3; P < 0.0001) and 29.2% (95% CI 25.4-32.9; P < 0.0001), respectively. CONCLUSIONS: Launch of the vonoprazan triple-drug blister pack had a significant impact on the success rate of clarithromycin triple therapy, with greater proportions of vonoprazan and combination blister pack use. Introducing an easy-to-use formulation may be effective in changing prescribing practice and subsequent patient outcomes.