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Unified Medical Language System (UMLS)

UMLS Vocabularies

RXNORM (RXNORM) - Metathesaurus Representation

This page lists UMLS Metathesaurus data elements and traces them back to the specific source data that populates them.



RxNorm, a standardized nomenclature for clinical drugs, is produced by the National Library of Medicine. Data files are released monthly and available by download. Within each Metathesaurus cycle, RxNorm is updated multiple times. This document reflects the latest cumulative update. The scope of RxNorm is determined by the combined scope of its source vocabularies which include the following:

Sources Description
ATC_2020_20_09_08 Anatomical Therapeutic Chemical Classification System
CVX_2020_07_28 Vaccines Administered
DRUGBANK5.0_2020_07_30 DrugBank
GS_2020_08_13 Gold Standard Drug Database
MMSL_2020_08_01 Multum MediSource Lexicon
MMX_2020_08_10 Micromedex RED BOOK
MTHCMSFRF_2014_20_09_08 Metathesaurus CMS Formulary Reference File
MTHSPL_2020_08_28 Metathesaurus FDA Structured Product Labels
NDDF_2020_08_12 FDB MedKnowledge
RXNORM_20AA_200908F RxNorm Vocabulary
USP_2020_02_06_20_09_08 USP Compendial Nomenclature
VANDF_2020_08_03 Veterans Health Administration National Drug File

Note: Selected portions of MSH and SNOMEDCT are included in the RxNorm release files, however, they are not processed as part of RxNorm for the Metathesaurus except in assigning RXCUI and RXAUI attributes. All MSH or SNOMEDCT data in the Metathesaurus comes directly from that source's data files. This document describes how the RxNorm release files (RXN*RRF) are processed for representation in the UMLS Metathesaurus. It does not cover processing of individual source vocabularies for inclusion in RxNorm.

Summary of Changes

New attribute name (ATN) = NHRIC (National Health Related Items Code).

Source Provided Files:

RXNORM data files are released monthly and available by download.

File Name Description
RXNCONSO.RRF Concept and source information.
RXNDOC.RRF Abbreviated values.
RXNREL.RRF Relationship information, including synonymy
RXNSAB.RRF Source information.
RXNSAT.RRF Attribute information.
RXNSTY.RRF Semantic type information.
RXNATOMARCHIVE.RRF Archive data. Not used.
RXNCUICHANGES.RRF CUI changes. Not used.


  • SDUI: RXNCONSO.SDUI (Currently always blank).

Atoms (MRCONSO):

Term Type

Term types are extracted from field 13 of RXNCONSO.RRF.


For many RxNorm and subsource termtypes, the suppressibility value can be either "O" or "E". For all others, the value is "N". Suppressibility values are extracted from field 17 of RXNCONSO.RRF.

In addition, source NDC attributes may have SUPPRESS="O" or "Y".

Attributes (MRSAT):

All attribute names and their values are extracted from field 9 and 11 of RXNSAT.RRF except for RXCUI and RXAUI which are created using RXNCONSO.RRF.

Definitions (MRDEF):

There are no DEFINITIONS in RXNORM or subsources.

Relationships (MRREL):

All relationships are extracted from field 4 (REL) and field 8 (RELA) of RXNREL.RRF

For detailed information on relationships, see RxNorm documentation

Mappings (MRMAP):

There are no mappings present in RxNorm.