In times of crisis, such as the Covid-19 pandemic, social divisions caused by dissensus about controversial government policies escalate due to widespread uncertainty and anxiety, fuelled by the proliferation of covert and overt manipulative strategies in official discourses. Like citizens in other countries, Swedes received during the Covid-19 crisis scarce or inconsistent information, and potentially misleading messages, while seeking to preserve a trust-based and tradition-rooted national consensus. Using a pragma-rhetorical and argumentation framework of analysis, this study scrutinizes the controversies emerging from the polarization of online comments made by reactive and counter-reactive citizens who either supported or challenged the controversial policies promoted by the Swedish Public Health Agency. The fallacies underlying the commenters’ arguments and counter-arguments show how initially reasonable discussions turned into deeply polarized disputes, as a manifestation of social dissent.