Consumers' worse-than-expected disconfirmation in ecommerce settings leads to several negative consequences, such as product returns and sales reductions. In contrast to common remedy strategies, a novel, proactive strategy, consumer inoculation, was employed in our study to alleviate consumers' disconfirmation responses. A two-phase (prepurchase and postsale) longitudinal experiment was conducted to examine the effects of prepurchase inoculation and booster inoculation on consumers' disconfirmation responses. A chi-square test and analysis of variance (ANOVA) were used to analyze the data. The research findings showed that consumers who received the booster inoculation exhibited significantly weaker disconfirmation responses (less dissatisfaction, fewer return intentions, and weaker negative word-of-mouth intentions). Our research can provide meaningful implications for inoculation research and practical value for ecommerce companies to reduce postsale costs.