RxNorm is a standardized nomenclature for clinical drugs produced by the National Library of Medicine to improve drug terminology interoperability and patient safety. It represents drugs in a Semantic Normal Form defined by ingredients, strengths, and dosage. RxNorm contains prescription and over-the-counter drug names in the US, excluding formulations with more than three ingredients. It is organized by concept and used in applications like RxNav and MyMedicationList by researchers, doctors, pharmacists and other healthcare professionals.