Science communication on a product-harm situation aims to create awareness on the product's potential impacts for consumers. However, consumers tend to overestimate the information provided, due to possible halo effects. Here we designed a contextual model of halo development including individual and message characteristics detected in the literature as potential moderators. Our experimental study, based on a sample of 3,766 European respondents, evaluates these halo moderators in the context of a product-harm science communication. The results reveal a stronger halo effect on consumers' beliefs when the focal topic is considered as more important (health vs. ethics) and simultaneously when the source of information is more credible (official vs. non-official). Highly involved consumers are also subject to greater halo effects. Suggested implications mainly focus on the need to consider potential amplifying halo effects and on the importance of responding to a product-harm communication via a very accurate communication approach.