Iron sucrose (IS) is a highly complex colloidal suspension used to treat anemia. Addressing the problems of quality, safety and efficacy within IS and its follow-on versions (ISSs), regulatory agencies recently underlined the need of new assays to characterize these drugs. In this perspective, innovative analytical methods for the physicochemical characterization of IS and several ISSs were developed, retrieving statistically significant differences within the drugs investigated. These specifically tailored assays might serve as tools for the establishment of IS's critical quality attributes as well as tools for the evaluation of degree of similarity between IS and ISSs and they represent the first example of an orthogonal characterization approach in the framework of non-biological complex drugs. Moreover, the need of specific multimethod strategies for characterizing iron polymaltose complex, as another example of nanomedicines to contrast anemia, was emphasized.