Error-Prone Abbreviations

ERROR-PRONE ABBREVIATIONS
The abbreviations 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 abbreviations should never be used when communicating medical information.
Abbreviations	Intended Meaning	Misinterpretation	Correction
µg	Microgram	Mistaken as “mg”	Use “mcg”
AD, AS, AU	Right ear, left ear, each ear	Mistaken as “OD, OS, OU” (right eye, left eye, each eye)	Use “right ear”, “left ear”, or “each ear”
OD, OS, OU	Right eye, left eye, each eye	Mistaken as “AD, AS, AU” (right ear, left ear, each ear)	Use “right eye”, “left eye”, or “each eye”
BT	Bedtime	Mistaken as “BID” (twice daily)	Use “bedtime”
cc	Cubic centimeters	Mistaken as “u” (units)	Use “mL”
D/C	Discharge or discontinue	Premature discontinuation of medications if D/C (intended to mean “discharge”) has been misinterpreted as “discontinued” when followed by a list of discharge medications	Use “discharge” or “discontinue”
IJ	Injection	Mistaken as “IV” (intravenous) or “intrajugular”	Use “injection”
IN	Intranasal	Mistaken as “IM” (intramuscular) or “IV” (intravenous)	Use “intranasal” or “NAS”
HS	Half-Strength	Mistaken as bedtime	Use “half-strength” or “bedtime”
hs	At bedtime, hours of sleep	Mistaken as half-strength	Use “half-strength” or “bedtime”
IU*	International unit	Mistaken as “IV” (intravenous) or 10 (ten)	Use “units”
o.d. or OD	Once daily	Mistaken as “right eye” (OD-oculus dexter), leading to oral liquid medications administered in the eye	Use “daily”
OJ	Orange juice	Mistaken as “OD or OS” (right or left eye); drugs meant to be diluted in orange juice may be given in the eye	Use “orange juice”
Per os	By mouth, orally	The “os” can be mistaken as “left eye” (OS-oculus sinister)	Use “PO”, “by mouth”, or “orally”
q.d. or QD*	Every day	Mistaken as “q.i.d.” (four times daily), especially if the period after the “q” or the tail of the “q” is misunderstood as an “i”	Use “daily”
qhs	Nightly at bedtime	Mistaken as “qhr” or every hour	Use “nightly”
qn	Nightly at bedtime	Mistaken as “qh” (every hour)	Use “nightly” or “at bedtime”
q.o.d. or QOD*	Every other day	Mistaken as “q.d.” (daily) or “q.i.d.” (four times daily) if the “o” is poorly written	Use “every other day”
q1d	Daily	Mistaken as “q.i.d.” (four times daily)	Use “daily”
q6PM, etc.	Every evening at 6PM	Mistaken as “every 6 hours”	Use “daily at 6PM” or “6 PM daily”
SC	Subcutaneous	Mistaken as “SL” (sublingual)	Use “subcut” or “subcutaneously”
SQ	Subcutaneous	Mistaken as “5 (five) every”	Use “subcut” or “subcutaneously”
sub q	Subcutaneous	The “q” in “sub q” has been mistaken as “every” (eg, a heparin dose ordered “sub q 2 hours before surgery” misunderstood as every 2 hours before surgery)	Use “subcut” or “subcutaneously”
ss	Sliding scale (insulin) or ½ (apothecary)	Mistaken as “55”	Spell out “sliding scale”; use “one-half” or “½”
SSRI	Sliding scale regular insulin	Mistaken as selective-serotonin reuptake inhibitor	Spell out “sliding scale (insulin)”
SSI	Sliding scale insulin	Mistaken as Strong Solution of Iodine (Lugol’s)	Spell out “sliding scale (insulin)”
i/d	One daily	Mistaken as “tid” (three times daily)	Use “1 daily”
TIW or tiw	3 times a week	Mistaken as “3 times a day” or “twice in a week”	Use “3 times weekly”
U or u*	Unit	Mistaken as 0 (zero) or 4 (four), causing a 10-fold overdose or greater (eg, 4U seen as 40 [forty] or 4u seen as 44 [forty-four]); mistaken as “cc” so dose given in volume instead of units (eg, 4u seen as 4cc)	Use “unit”
UD	As directed (“ut dictum”)	Mistaken as unit dose (eg, diltiazem 125mg IV infusion “UD” misinterpreted as meaning to give the entire infusion as a unit [bolus] dose)	Use “as directed”
NOTES
*Included on The Joint Commission’s “minimum list” of dangerous abbreviations, acronyms, and symbols that must be included on an organization’s “Do Not Use” list, effective January 1, 2004. For more information visit http://www.jointcommission.org.
REFERENCES
Source: Institute for Safe Medication Practices. Error-Prone Abbreviations, Symbols, and Dose Designations. 2017. Available at: http://www.ismp.org/Tools/errorproneabbreviations.pdf. (Rev. 2/2020)

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