Objective Functional gastrointestinal (GI) symptoms can develop into persistent states often categorised as the irritable bowel syndrome (IBS). In the severe end of the GI symptom continuum, other coexisting symptoms are common. We aimed to investigate the GI symptom continuum in relation to mortality and development of GI diseases, and to examine if coexisting symptoms had an influence on the outcomes. Material and methods A longitudinal population-based study comprising two 5-year follow-up studies: Dan-Monica1 (1982–1987) and Inter99 (1999–2004). IBS was defined according to a population-based IBS definition. The pooled cohort (n = 7278) was followed until December 2013 in Central Registries. Results Fifty-one percent had no GI symptoms, 39% had GI symptoms but never fulfilled the IBS definition, 8% had fluctuating IBS and 2% had persisting IBS. There was no significant association between symptom groups and mortality (p = 0.47). IBS and GI symptoms with abdominal pain were significantly associated with development of GI diseases. Only GI symptoms with abdominal pain were associated with development of severe GI diseases (HR: 1.38; 95% CI: [1.06–1.79]). There were no statistically significant interactions between symptom groups and coexisting symptoms in relation to the two outcomes. Conclusions GI diseases were seen more frequently, but IBS was not associated with severe GI diseases or increased mortality. Clinicians should be more aware when patients do not fulfil the IBS definition, but continue to report frequent abdominal pain. Coexisting symptoms did not influence mortality and development of GI diseases.