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. 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.
Abbreviations	Intended Meaning	Misinterpretation	Correction
Doses or Measurement Units
cc	Cubic centimeters	Mistaken as “u” (units)	Use “mL”
IU*	International unit(s)	Mistaken as “IV” (intravenous) or the number 10	Use “unit(s)” (International units can be expressed as units alone)
l	Liter	Lowercase letter “l” mistaken as the number 1	Use “L”
ml	Milliliter	Lowercase letter “l” mistaken as the number 1	Use “mL”
MM or M	Million	Mistaken as “thousand” (M has been used to abbreviate both million and thousand)	Use “million”
M or K	Thousand	Mistaken as “million” (M has been used to abbreviate both million and thousand)	Use “thousand”
Ng or ng	Nanogram	Mistaken as “mg” or “nasogastric”	Use “nanogram” or “nanog”
U or u*	Unit(s)	Mistaken as 0 or 4, causing a 10-fold overdose or greater (eg, 4U seen as 40 or 4u seen as 44); mistaken as “cc” so dose given in volume instead of units (eg, 4u seen as 4cc)	Use “unit(s)”
μg	Microgram	Mistaken as “mg”	Use “mcg”
Route of Administration
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”
IJ	Injection	Mistaken as “IV” or “intrajugular”	Use “injection”
IN	Intranasal	Mistaken as “IM” (intramuscular) or “IV”	Use “NAS” or “intranasal”
IT	Intrathecal	Mistaken as “intratracheal”, “intratumor”, “intratympanic”, or “inhalation therapy”	Use “intrathecal”
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”
Per os	By mouth, orally	The “os” can be mistaken as “left eye” (OS)	Use “PO”, “by mouth”, or “orally”
SC, SQ, sq, or sub q	Subcutaneous(ly)	“SC” and “sc” mistaken as “SL” or “sl” (sublingual); SQ mistaken as “5 every”; The “q” in “sub q” has been mistaken as “every”	Use “SUBQ” or “subcutaneous(ly)”
Frequency or Instructions
HS	Half-strength	Mistaken as “bedtime”	Use “half-strength”
hs	At bedtime, hours of sleep	Mistaken as “half-strength”	Use “HS” for bedtime
o.d. or OD	Once daily	Mistaken as “right eye” (OD), leading to oral liquid medications given in the eye	Use “daily”
Q.D., QD, 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” (every hour)	Use “nightly” or “HS” for bedtime
Qn	Nightly or at bedtime	Mistaken as “qh” (every hour)	Use “nightly” or “HS” for bedtime
Q.O.D., QOD, q.o.d., or qod*	Every other day	Mistaken as “qd” (daily) or “qid” (four times daily) if the “o” is poorly written	Use “every other day”
q1d	Daily	Mistaken as “qid” (four times daily)	Use “daily”
q6PM, etc.	Every evening at 6 PM	Mistaken as “every 6 hours”	Use “daily at 6 PM” or “6 PM daily”
SSRI	Sliding scale regular insulin	Mistaken as selective-serotonin reuptake inhibitor	Use “sliding scale (insulin)”
SSI	Sliding scale insulin	Mistaken as Strong Solution of Iodine (Lugol’s)	Use “sliding scale (insulin)”
TIW or tiw	3 times a week	Mistaken as “3 times a day” or “twice in a week”	Use “3 times weekly”
BIW or biw	2 times a week	Mistaken as “2 times a day”	Use “2 times weekly”
UD	As directed (ut dictum)	Mistaken as unit dose (eg, order of “dilTIAZem infusion UD” mistakenly given as a unit [bolus] dose)	Use “as directed”
Miscellaneous
BBA	Baby boy A (twin)	B in BBA can be mistaken as twin B rather than gender (boy)	Use mother’s last name, baby’s gender (boy or girl), and distinguishing identifier for all multiples when assigning identifiers to newborns (eg, Smith girl A, Smith girl B)
BGB	Baby girl B (twin)	B at end of BGB can be mistaken as gender (boy) not twin B
D/C	Discharge or discontinue	Premature discontinuation of medications if D/C (intended to mean “discharge”) mistaken as “discontinued” on a medication list	Use “discharge” and “discontinue” or “stop”
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”
Period following abbreviations (eg, mg., mL.)	mg or mL	Unnecessary period mistaken as the number 1, especially if written poorly	Use without a terminal period (eg, “mg”, “mL”, etc.)
SS or ss	Single strength, sliding scale (insulin), signs and symptoms, or ½ (apothecary)	Mistaken for each other or the number “55”	Use “single strength”, “sliding scale”, “signs and symptoms”, or “one-half” or “½”
* Included on The Joint Commission’s “Do Not Use” list (Information Management standard IM.02.02.01) and must be included on an organization’s “Do Not Use” list.
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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