Idiopathic multicentric Castleman disease (iMCD) is a rare lymphoproliferative disorder characterized by a hyperinflammatory state driven primarily by hypercytokinemia, particularly interleukin-6 (IL-6). iMCD patients have historically poor outcomes, particularly among patients who were not properly treated. Among several factors, one potential reason for delayed treatment initiation could be a lack of understanding of the clinical trajectory of iMCD patients regarding the development of disease-associated morbidities over time. A better understanding of the natural history of iMCD, particularly the evolution and prevalence of morbidities, will be helpful for making timely decisions about appropriate treatment and potentially mitigate morbidity burden in these patients. The primary objective of this study was to evaluate the pattern of morbidities and their prevalence in iMCD patients using a nationally representative health claims dataset. We additionally analyzed healthcare utilization of iMCD patients by evaluating length of hospital stays and visits to emergency departments by these patients.