Error-Prone Symbols

ERROR-PRONE SYMBOLS
The symbols found in this table have been reported to the Institute for Safe Medical Practices (ISMP) through the ISMP Medication Error Reporting Program as being frequently misinterpreted and involved in harmful medication errors. These symbols should never be used when communicating medical information. 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.
Symbol	Intended Meaning	Misinterpretation	Correction
ʒ	Dram	Mistaken as “3”	Use the metric system
♍	Minim	Mistaken as “mL”	Use the metric system
x1	Administer once	Administer for 1 day	Use explicit words (eg, “for 1 dose”)
> and <	More than and less than	Mistaken as opposite of intended; incorrect symbol used mistakenly; “<” mistaken as “4” when handwritten (eg, “<10” mistaken as “40”)	Use “more than” or “less than”
↑ and ↓	Increase and decrease	Mistaken as opposite of intended; incorrect symbol used mistakenly; ↑ mistaken as the letter T, leading to misinterpretation as the start of a drug name, or mistaken as the numbers 4 or 7	Use “increase” and “decrease”
/ (slash mark)	Separates two doses or indicates “per”	Mistaken as the number 1 (eg, “25 units/10units” mistaken as “25 units and 110 units”)	Use “per” rather than a slash mark to separate doses
@	At	Mistaken as “2”	Use “at”
&	And	Mistaken as “2”	Use “and”
+	Plus or and	Mistaken as “4”	Use “plus”, “and”, or “in addition to”
°	Hour	Mistaken as a zero (eg, q2° seen as q 20)	Use “hr”, “h”, or “hour”
Φ or ∅	Zero, null sign	Mistaken as numerals 4, 6, 8, and 9	Use “0” or “zero”, or describe intent using whole words
#	Pound(s)	Mistaken as a number sign	Use the metric system (kg or g) rather than pounds; if referring to pounds, use “lb”
REFERENCES
Source: Institute for Safe Medication Practices (ISMP). ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations. ISMP; 2021. Available at: https://www.ismp.org/recommendations/ error-prone-abbreviations-list. Accessed October 5, 2023. (Rev. 10/2023)

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