Message fatigue is an aversive motivational state associated with chronic overexposure to similar messages. Most extant research has relied on cross-sectional designs, precluding causal inferences about the relationship among exposure, fatigue, and persuasive outcomes. To address this limitation, we conducted a two-wave online survey using a nationwide U.S. adults sample in the context of COVID-19 and influenza vaccine messaging (Wave 1: N = 601; Wave 2: N = 305). Cross-lagged panel analyses revealed a positive association between exposure and fatigue within Wave 2, whereas exposure at Wave 1 negatively predicted fatigue at Wave 2. Within each wave, fatigue was negatively associated with adaptive behavioral intentions. Information-induced emotions, including hope, anger, and fear, significantly correlated with fatigue. Unexpectedly, information-seeking intent at Wave 1 predicted lower message fatigue at Wave 2. Implications for message fatigue research and effective health communication are discussed.
