What is on the Joint Commission "Do Not Use" list?

U and u for unit; IU; QD and its variants; QOD and its variants; trailing zeros (X.0 mg); a missing leading zero (.X mg); MS; and MSO4 and MgSO4. Eight rows in total.

Is cc on the "Do Not Use" list?

No. It is widely discouraged and appears on ISMP's error-prone abbreviation list, but it is not a row on the Joint Commission's Official "Do Not Use" List. Exam items are often built on exactly this distinction.

Can a trailing zero ever be used?

Yes, in one narrow case: where it is required to show the precision of a reported value, such as a laboratory result, the size of a lesion on imaging, or a catheter or tube size. It may never be used in a medication order or other medication-related documentation.

Documentation shorthand

The “Do Not Use” list

Q: Where does the list apply?

To all orders and all medication-related documentation that is handwritten — including free-text computer entry — or on pre-printed forms.

Eight notations that must not appear in an order, because each one has been misread in a way that harmed someone. You still have to recognize all of them — they are in older records — which is why they are in this dictionary rather than left out of it.

Where it applies. The list applies to all orders and all medication-related documentation that is handwritten — including free-text computer entry — or on pre-printed forms.

The Official list

Do not use	Why it is dangerous	Write instead
U, u	Mistaken for “0” (zero), the number “4” (four), or “cc”.	Write “unit”
IU	Mistaken for IV (intravenous) or the number 10 (ten).	Write “International Unit”
Q.D., QD, q.d., qd	Mistaken for each other.	Write “daily”
Q.O.D., QOD, q.o.d., qod	The period after the Q is mistaken for “I”, and the “O” is mistaken for “I”.	Write “every other day”
Trailing zero (X.0 mg)	The decimal point is missed, so the dose reads ten times larger. One exception, and it is narrow: a trailing zero may be used only where it is required to show the precision of a value being reported — laboratory results, imaging studies reporting the size of a lesion, catheter or tube sizes. It may not be used in medication orders or other medication-related documentation.	Write X mg
Lack of leading zero (.X mg)	The decimal point is missed, so the dose reads ten times larger.	Write 0.X mg
MS	Can mean morphine sulfate or magnesium sulfate.	Write “morphine sulfate”
MSO4 and MgSO4	Confused for one another.	Write “magnesium sulfate”

Discouraged, but not on the list

These turn up constantly in study material described as “Do Not Use” abbreviations. They are error-prone and worth avoiding, and they are not rows on the Official list — they appear on ISMP’s error-prone abbreviation list and among the notations named as candidates for future inclusion. An exam item asking which of these is on the Official list is testing this boundary and nothing else.

Notation	Why it is error-prone	Write instead
cc	Handwritten cc has been misread as the letter “u”, and from there as a unit.	Write “mL”
µg	The microgram symbol has been misread as “mg” — a thousandfold error.	Write “mcg”
> and <	Misread as the number 7 or the letter L, and confused with each other.	Write “greater than” / “less than”
@	Mistaken for the number 2.	Write “at”
Abbreviated drug names	One abbreviation can stand for several different drugs.	Write the drug name in full

How it gets tested

Three item types account for almost all of it. The first is straight recall: which of these four should not be written in an order. The second is the boundary above — an option list that mixes Official rows with merely error-prone notations.

The third is the one people lose, because it is typography rather than vocabulary: the trailing zero and the leading zero. Both exist for the same reason — a decimal point that does not survive a photocopy or a fast read turns 1.0 mg into 10 mg, and .5 mg into 5 mg. Ten times the dose, from one dropped mark.

Related terms

u iu qd qod cc mcg mg ml five-rights

Sources

Every figure on this page comes from one of the documents below, with the date it was read. Requirements change; if a source has moved on since that date, the source is right and this page is out of date.

The Joint Commission — Official "Do Not Use" List of Abbreviations Read August 22, 2026
UTMB Anesthesiology — reproduction of the Joint Commission list (used because the Joint Commission page returns 403 to automated requests) Read August 22, 2026

Page facts last verified August 22, 2026.

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Frequently asked

What is on the Joint Commission "Do Not Use" list?: U and u for unit; IU; QD and its variants; QOD and its variants; trailing zeros (X.0 mg); a missing leading zero (.X mg); MS; and MSO4 and MgSO4. Eight rows in total.
Is cc on the "Do Not Use" list?: No. It is widely discouraged and appears on ISMP's error-prone abbreviation list, but it is not a row on the Joint Commission's Official "Do Not Use" List. Exam items are often built on exactly this distinction.
Can a trailing zero ever be used?: Yes, in one narrow case: where it is required to show the precision of a reported value, such as a laboratory result, the size of a lesion on imaging, or a catheter or tube size. It may never be used in a medication order or other medication-related documentation.
Where does the list apply?: To all orders and all medication-related documentation that is handwritten — including free-text computer entry — or on pre-printed forms.

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