Exploring temporal relationships among worrying, anxiety, and somatic symptoms

•Anxiety and functional somatic symptoms (FSS) frequently co-occur.•The nature of the relationship between anxiety and FSS is unclear.•This study modeled the relationship between FSS and anxiety within individuals using diary data.•Heterogeneity in these within-person relationships was observed.•FSS appeared to be associated with anxiety persistence.•This approach may contribute to developing patient tailored explanatory models of FSS.