This study addresses how issue familiarity conditions longitudinal news framing effect dynamics. Comparing how the economic consequences frame impacts interpretation of two global problems-antimicrobial resistance and climate change-we study longitudinal effects across two similar issues varying significantly in salience and politicization, focusing on how various effect dynamics (single, repetitive, and counter-framing exposure) influence citizens' beliefs over time. A longitudinal experiment conducted with a probability-recruited sample in Sweden (N = 1,956) reveals (1) clear framing effects for both issues, (2) dynamics driven primarily by recency mechanisms, and (3) that individual differences in baseline belief certainty condition news framing effects. In sum, while the same news frame can have very similar effects on different issues, the findings suggest a "dual role" of issue familiarity, potentially conditioning the specific longitudinal effect dynamics, on the one hand, and effect susceptibility, on the other hand.