The field of nanotechnology is at the forefront of a scientific revolution, where the term “nano” transcends mere size and opens the door to enormous possibilities. In the context of drug development, the selection of a suitable drug delivery system (corresponding to a certain active pharmaceutical ingredient) is a pivotal decision. Accordingly, nanosystems have emerged as a promising avenue, offering innovative solutions, and gaining recognition for addressing healthcare issues. While these products hold immense promise, they have faced certain complexities in their translation from the preclinical to the clinical setting, reflected in the lack of proper assessment protocols for quality and safety aspects and, consequently, an insufficiently defined regulatory environment. Since the groundbreaking US Food and Drug Administration (FDA) approval of liposomal doxorubicin in 1995, approximately 80 nanomedicine products have received regulatory approval so far. Recent attention has gravitated toward lipid-based nanomedicines, particularly in the development of mRNA vaccines during the COVID-19 pandemic, further highlighting their significance. However, the relatively modest number of approved nanomedicines compared to the extensive research efforts raises important questions and underscores areas of uncertainty. This article provides an overview of the challenges in defining nanomedicines, their properties, the complexities of regulatory frameworks, and the imperative for standardized characterization protocols.