We investigated the relationship between different media sources (traditional media, online news media, online health sources, social media) and COVID-19 related conspiracy beliefs, and how these change over time, using four-wave panel data from a representative sample of the Dutch population (N = 1,166). Across waves, 0.1%–3.4% of our sample were certain the selected conspiracy theories were true, though this belief was unstable over time. Random intercept cross-lagged panel models revealed that individuals’ temporary level of conspiracy beliefs did not significantly depend on their temporary level of media use at a previous occasion, or vice versa. However, significant correlations at the group level indicated that more frequent use of health-related and social media sources were associated with higher levels of conspiracy beliefs. These results suggest that relationships between media use and conspiracy beliefs are nuanced. Underlying processes should be investigated to develop tailored communication strategies to combat the ongoing infodemic.