Do Not Use

Dangerous Abbreviations, Symbols and Dose Designations

The abbreviations, symbols, and dose designations found in this table have been reported as being frequently
misinterpreted and involved in harmful medication errors. They should NEVER be used when communicating
medication information.

Abbreviation Intended Meaning Problem Correction

Mistaken for “0” (zero), “4” (four), or
U unit Use “unit”.
cc.
Mistaken for “IV” (intravenous) or
IU international unit Use “unit”.
“10” (ten).
Misinterpreted because of similar
Abbreviations abbreviations for multiple drugs;
for drug e.g., MS, MSO4 (morphine
Do not abbreviate drug names.
names sulphate), MgSO4 (magnesium
sulphate) may be confused for one
another.
QD and QOD have been mistaken
QD Every day for each other, or as ‘qid’. The Q Use “daily” and “every other
QOD Every other day has also been misinterpreted as “2” day”.
(two).
Mistaken for “right eye”
OD Every day Use “daily”.
(OD = oculus dexter).
Left eye, right eye, both Use “left eye”, “right eye” or
OS, OD, OU May be confused with one another.
eyes “both eyes”.
Interpreted as “discontinue
D/C Discharge whatever medications follow” Use “discharge”.
(typically discharge medications).
cc cubic centimetre Mistaken for “u” (units). Use “mL” or “millilitre”.
Mistaken for “mg” (milligram)
µg
microgram resulting in one thousand-fold Use “mcg”.
overdose.
Symbol Intended Meaning Potential Problem Correction
© 2006 ISMP Canada, reaffirmed 2018

@ at Mistaken for “2” (two) or “5” (five). Use “at”.

Mistaken for “7”(seven) or the letter
> Greater than Use “greater than”/”more than”
“L” .
< Less than or “less than”/”lower than”.
Confused with each other.
Dose
Intended Meaning Potential Problem Correction
Designation
Never use a zero by itself after
Decimal point is overlooked
Trailing zero X.0 mg a decimal point.
resulting in 10-fold dose error.
Use “X mg”.
Lack of Decimal point is overlooked Always use a zero before a
. X mg
leading zero resulting in 10-fold dose error. decimal point. Use “0.X mg”.
Adapted from ISMP’s List of Error-Prone Abbreviations, Symbols, and Dose Designations 2006

Report actual and potential medication errors to ISMP Canada at

https://www.ismp-canada.org/err_report.htm or by calling 1-866-54-ISMPC.

Permission is granted to reproduce material for internal communications with proper attribution. Download from: www.ismp-canada.org/dangerousabbreviations.htm