An unZIP utility such as WinZIP can be used to open the ZIP files once downloaded. The RRF files are pipe-delimited text files (with a file extension of .RRF instead of .txt) which can be opened with a text editor such as Notepad.

Some of the files are large and cannot be opened with simple text editors. More robust text editors, such as Notepad++ for Windows and TextWrangler for Mac, work well. However, the RxNorm data are explored more effectively when loaded into a database or manipulated with command line tools, like grep or awk.

Several resources provide new RXCUI information.

• RxNorm Monthly Releases – The RXNCONSO.RRF file in the monthly releases contain new and existing RxNorm drug names and codes and is available for download the first Monday of every month or the first Tuesday if Monday is a U.S. Federal holiday.
• RxNorm Weekly Releases – The RXNCONSO.RRF file in the weekly releases contain select new data and is available for download every Wednesday or Thursday if Wednesday is a holiday.
• RxNav – Perform a search on the first Monday or Tuesday of the month, as it is updated with the RxNorm monthly release.
• DailyMed – Perform a search on Thursdays, as DailyMed is typically updated with the Wednesday RxNorm weekly releases. To find the RXCUI in DailyMed (if available):
  • Go to the desired DailyMed drug label page.
  • Click on “RxNorm” under the “MORE INFO FOR THIS DRUG” section near the bottom of the left panel or the bottom of the page.
  • A pop-up window will appear with relevant RxNorm information.

You can also email rxnorminfo@nlm.nih.gov requesting information.

There are several reasons why you might not be able to find an RXCUI in RxNorm.

• Merged into another RXCUI – When two concepts are determined to be synonymous, they are merged together. Once merged, only one of the RXCUIs remains active. You can find a record of these merges in the RxNorm history files (e.g. RXNCUI.RRF, RXNATOMARCHIVE.RRF, RXNCUICHANGES.RRF).
• Retired – If a concept is created in error, it may have been retired without merging into another concept. As with merged RXCUIs, look in the history files for a record of these changes.
• Not a valid RXCUI – If you cannot find the RXCUI in RXNCONSO.RRF or the history files, your RXCUI is not a valid RXCUI. RXCUIs with an NLM-created RxNorm normalized name are documented in the RxNorm files. However, RXCUIs for products without an RxNorm normalized name are considered out of scope and are transient and can change or be deleted by the source vocabulary provider at any time.

There are several reasons why an RXCUI does not have an associated RxNorm normalized name.

• Out of scope – Some information provided by source vocabularies is out of scope for RxNorm. While this information is grouped into concepts and given RXCUIs, RxNorm normalized names are not created for this information.
• Ambiguous – Some information provided by source vocabularies are too vague and for a specific RxNorm normalized name to be assigned.
• Base atom – A Base atom often lacks an RxNorm normalized name because a Base atom contains NDCs representing several different drug products. For more information about Base atoms, see Section 9: Duplicating Source Asserted Atoms (with NDC conflicts) of the RxNorm Technical Documentation.

Yes, an RXCUI-NDC crosswalk is available in the RXNSAT.RRF file of the RxNorm data files. The NDC values are in the ATV column where ATN = ‘NDC'. See Section 14.2 Sample Database Queries of the RxNorm Technical Documentation for several NDC-related sample database queries.

To get NDC, RXCUI, and drug names, see this brief video tutorial on Mapping NDC, RXCUI, and Drug Names in the RxNorm Files.

Yes, the RxNorm dataset contains limited drug classification information, primarily from the following source vocabularies: Anatomical Therapeutic Chemical Classification System (ATC) and Veterans Health Administration National Drug File (VANDF). For example, see this document for an SQL query with explanations: SQL Query to get ATC1-4 Drug Classes for Single-Ingredient RxNorm Generic Drugs (TTY = SCD).

However, the database queries to obtain classification information from the RxNorm data files can be long and cumbersome. To assist users, the RxClass Browser, RxClass API, and several preset workflows in RxMix provide drug class information, some of which are not available in the RxNorm data files. For more information about RxClass, see the RxClass Overview.

Learn more about RxMix on the RxMix Tutorial page. To see existing workflows in RxMix:

• Go to: https://mor.nlm.nih.gov/RxMix/.
• Click on “From workflow library”.
• Browse the workflows of interest in the pop-up screen.

Familiarity with the RxNorm data and file structure will be imperative in querying the data effectively. Review the RxNorm Technical Documentation, particularly the appendices, and the RxNorm Overview (i.e. relationship diagram under “What does the RxNorm model look like?”) for useful information.

Here are links to specific pages to help you get started:

• Appendix 5 - RxNorm Term Types (TTY)
• Appendix 1 - RxNorm Relationships (RELA)
• Appendix 4 - RxNorm Attributes
• Section 14.2  Sample Database Queries
• Section 3.1  Source Vocabularies (i.e. individual vocabulary pages (e.g. ATC) contain “Data Examples with Sample Database Queries”)

Alternatively, the RxNav page provides web-based resources, such as the RxNav browser and application programming interfaces (APIs), to browse and retrieve RxNorm data.