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News Release

ISMP Updates List of Error-Prone Abbreviations, Symbols, and Dose Designations

Revised Tool Can Help Healthcare Organizations Update Their Own “Do Not Use” Lists

The Institute for Safe Medication Practices (ISMP) has released updated recommendations regarding conventions used to communicate medical information that can be misinterpreted. All items on the 2024 List of Error-Prone Abbreviations, Symbols, and Dose Designations were reported through ISMP’s national, voluntary error reporting program and have been involved in harmful or potentially harmful medication errors.

ISMP emphasizes that these abbreviations, symbols, and dose designations should NOT be used in verbal, handwritten, or electronic communications. This includes internal communications; verbal, handwritten, or electronic prescriptions; handwritten and computer-generated medication labels; drug storage bin labels; medication administration records; and screens associated with pharmacy and prescriber computer order entry systems, automated dispensing cabinets, smart infusion pumps, and other medication-related technologies.

“Healthcare organizations are encouraged to review the revised list to see if their internal “Do Not Use” lists require updating as well,” says Ann Shastay, MSN, RN, AOCN, Senior Manager, ISMP Publications.  

“ISMP’s list points out abbreviations, symbols, and dose designations that also are included on the Joint Commission’s “Do Not Use” list to offer a complete resource for easy reference.”

Some of the changes to the 2024 list include:

  • When a dose is being measured in nanograms, do not use “nanog” as an abbreviation. Use the full spelled-out word instead.
  • For intranasal medications, do not use “NAS” as an abbreviation. Use the full spelled-out word instead.
  • When a medication is intended to be used nightly at bedtime, do not use “nightly” or “HS” to mean at bedtime. Use QHS or qhs instead.
  • When indicating a half tablet, do not use reduced font-size fractions. Use text instead and avoid using fractions or decimals.
  • If a slash mark is needed to separate doses, do not use “per.” Use “and” instead.

For a copy of the current ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations, click here.


Renee Brehio, Medication Safety Anaylst and Editor,

About the Institute for Safe Medication Practices

The Institute for Safe Medication Practices (ISMP) is the nation’s first 501c (3) nonprofit organization devoted entirely to preventing medication errors. ISMP is known and respected for its medication safety information. For more than 30 years, it also has served as a vital force for progress. ISMP’s advocacy work alone has resulted in numerous necessary changes in clinical practice, public policy, and drug labeling and packaging. Among its many initiatives, ISMP runs the only national voluntary practitioner medication error reporting program, publishes newsletters with real-time error information read and trusted throughout the global healthcare community, and offers a wide range of unique educational programs, tools, and guidelines. In 2020, ISMP formally affiliated with ECRI to create one of the largest healthcare quality and safety entities in the world, and ECRI and the ISMP PSO is a federally certified patient safety organization by the U.S. Department of Health and Human Services. As an independent watchdog organization, ISMP receives no advertising revenue and depends entirely on charitable donations, educational grants, newsletter subscriptions, and volunteer efforts to pursue its life-saving work. 


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