Dangerous Abbreviations

Abbreviation Intended meaning Common Error

U Units Mistaken as a zero or a four (4) resulting in

overdose. Also mistaken for "cc"

(cubic centimeters) when poorly written.

µg Micrograms Mistaken for "mg" (milligrams) resulting in

an overdose.

Q.D. Latin abbreviation for The period after the "Q" has sometimes been

every day mistaken for an " I, " and the drug

has been given "QID" (four times daily) rather

than daily.

Q.O.D. Latin abbreviation for Misinterpreted as "QD" (daily) or "QID" (four

every other day times daily). If the "O" is

poorly written, it looks like a period or "I."

SC or SQ Subcutaneous Mistaken as "SL" (sublingual) when poorly

written.

T I W Three times a week Misinterpreted as "three times a day" or

"twice a week."

D/C Discharge; also discontinue Patient's medications have been prematurely

discontinued when D/C, (intended to mean

"discharge") was misinterpreted

as "discontinue," because it was followed

by a list of drugs.

HS Half strength Misinterpreted as the Latin abbreviation "HS"

(hour of sleep).

cc Cubic centimeters Mistaken as "U" (units) when poorly written.

AU, AS, AD Latin abbreviation for both ears; Misinterpreted as the Latin abbreviation "OU"

left ear; right ear (both eyes); "OS" (left eye); "OD" (right eye)

IU International Unit Mistaken as IV (intravenous) or 10(ten)

MS, MSO4, Confused for one another Can mean morphine sulfate or magnesium

MgSO4 sulfate

See the full Council Recommendation, Recommendations to Enhance Accuracy of Prescription Writing.