Conspiracism has become a topical issue in democracies around the world, eliciting debate in political theory and philosophy regarding its normative and practical implications, especially its potential negative effects on democratic systems. In this article, we analyse conspiracism through the lens of civility. The public virtue of civility plays a key role in democratic politics and in public life more generally, by helping to sustain democratic institutions and facilitating social interaction despite disagreement. If conspiracism undermines civility and contributes to incivility, as we argue in this article, that might have distinctively deleterious effects on democratic life. We begin by unpacking the concept of civility into three key dimensions: (a) civility as politeness, (b) moral civility and (c) justificatory civility. We then illustrate how conspiracism can contribute to incivility and harm democracy in each of the three dimensions but also how it can sometimes be harmless or even helpful for democracy.