RxNorm is intended to cover all prescription medications approved for human use in the United States. Prescription medications from other countries may be included as opportunities allow, a principal consideration being that there be an authoritative source of information about these drugs. Drugs are added to the vocabulary as new products are put on the market. Over-the-counter (OTC) medications will be added and covered, as well, when reliable information about the medications can be found. Drugs are added to the vocabulary as new products are put on the market.

An RxNorm clinical drug name reflects the active ingredients, strengths, and dose form composing that drug. When any of these elements vary, a new RxNorm drug name is created as a separate concept. Thus, an RxNorm name should exist for every strength and dose of every available combination of clinically significant ingredients.

National Drug Codes (NDCs) for specific drug products are linked to that product in RxNorm. RxNorm links its names to many of the drug vocabularies commonly used in pharmacy management and drug interaction software, including those of First Databank, Micromedex®, Gold Standard Alchemy, and Multum. By providing links between these vocabularies, RxNorm can mediate messages between systems not using the same software and vocabulary.