Post-truth politics is thought to harm knowledge and democracy. I argue that it can also fundamentally undermine epistemic autonomy in ways similar to the manipulative technique known as gaslighting. I identify three categories of post-truth rhetoric: the introduction of counternarratives, the discrediting of critics, and the denial of more or less plain facts. Like gaslighting, these post-truth strategies can undermine epistemic autonomy by eroding self-trust, in order to consolidate power. Focusing on the effects on the victim allows for new insights into the specific harms of post-truth politics and can help to combat and resist it.