Background: While there is considerable evidence for the positive effects of onsite peer support on health outcomes, few studies have addressed the impact of online peer support. Aims: This study differentiates between emotional (ES) and informational (IS) online peer support for people with celiac disease. We hypothesize that receiving ES and IS positively correlates with self-reported well-being and dietary compliance and that these relations would be moderated by the duration of illness. Method: We used a correlational, cross-sectional design (N = 369). Results: Both functions of support were positively related to well-being and dietary compliance. The strengths of the positive relationships between ES and both outcomes and IS and well-being were independent of the duration of illness. IS was significantly positively related to dietary compliance among participants with a longer duration of illness, but unrelated among participants with a shorter duration. Limitations: Due to the correlational design, we cannot infer causality. Conclusion: Our findings advance the understanding of online support in contexts where proper self-management is crucial for health outcomes.