Two 3(control versus LTI versus HTI) × 2(self-affirmation versus no self-affirmation)-experiments were conducted. The first study presented a news message on the treatability of bowel cancer (N = 717); the second study was about skin cancer (N = 342). The dependent variables were the intention to engage in preventive behaviors and message acceptance. The results showed that when participants were exposed to LTI, only when response efficacy was low, a self-affirmation procedure increased their intention to prevent cancer (experiment 1), and increased message acceptance (experiment 2). When participants were exposed to HTI, the self-affirmation procedure did not increase the intention, and even reduced message acceptance. The findings suggest that defensive processes were active in reaction to LTI, but not in reaction to HTI. Although publishing LTI and HTI information in the media serves legitimate goals, it may have positive but also negative unintended effects on preventive behaviors in the population.