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High-risk abbreviations
86 error-prone abbreviations, why each is flagged, and what to write instead.
| Abbreviation | Why it is flagged | Write instead |
|---|---|---|
| U | Can be mistaken for "0" (zero), "4" (four), or "cc" leading to 10-fold or greater overdose | Write "unit" |
| u | Lowercase "u" can be mistaken for "0" (zero), "4" (four), or "cc" | Write "unit" |
| IU | Can be mistaken for "IV" (intravenous) or "10" (ten) | Write "international unit" or "units" |
| QD | Can be mistaken for "QID" (four times daily) or "QOD" (every other day) | Write "daily" |
| Q.D. | Period after Q can be mistaken for "I", reading as QID | Write "daily" |
| q.d. | Can be mistaken for "q.i.d." (four times daily) | Write "daily" |
| qd | Can be mistaken for "qid" (four times daily) | Write "daily" |
| QOD | Can be mistaken for "QD" (daily) or "QID" (four times daily) | Write "every other day" |
| Q.O.D. | Can be mistaken for "Q.D." or "Q.I.D." | Write "every other day" |
| q.o.d. | Can be mistaken for "q.d." or "q.i.d." | Write "every other day" |
| qod | Can be mistaken for "qd" or "qid" | Write "every other day" |
| X.0 | Decimal point may be missed, causing 10-fold overdose | Never use trailing zeros; write "1 mg" not "1.0 mg" |
| .X | Decimal point may be missed, causing 10-fold overdose | Always use leading zero; write "0.5 mg" not ".5 mg" |
| MS | ISMP and Joint Commission list MS as error-prone/prohibited: morphine sulfate may be mistaken as magnesium sulfate. | Write "morphine sulfate" or "magnesium sulfate" in full |
| MSO4 | ISMP and Joint Commission list MSO4 as error-prone/prohibited: morphine sulfate may be mistaken as magnesium sulfate. | Write "morphine sulfate" |
| MgSO4 | ISMP and Joint Commission list MgSO4 as error-prone/prohibited: magnesium sulfate may be mistaken as morphine sulfate. | Write "magnesium sulfate" |
| ZnSO4 | ISMP lists ZnSO4 as error-prone: zinc sulfate may be mistaken as morphine sulfate. | Write "zinc sulfate" |
| μg | A visually similar microgram abbreviation can be mistaken for "mg" (milligram), creating a 1000-fold overdose risk. | Write "mcg" |
| µg | ISMP lists µg as error-prone: microgram may be mistaken as mg. | Write "mcg" |
| ug | Can be mistaken for "mg" - 1000-fold overdose risk | Write "mcg" |
| Ng | ISMP lists Ng/ng as error-prone: nanogram may be mistaken as mg or nasogastric. | Write "nanogram" |
| ng | ISMP lists Ng/ng as error-prone: nanogram may be mistaken as mg or nasogastric. | Write "nanogram" |
| cc | Can be mistaken for "U" (units) when poorly written | Write "mL" |
| AS | Can be mistaken for AD, AU, or OS | Write "left ear" |
| AD | Can be mistaken for AS, AU, or OD | Write "right ear" |
| AU | Can be mistaken for OU (both eyes) | Write "both ears" |
| IN | ISMP lists IN as error-prone: intranasal may be mistaken as IM or IV. | Write "intranasal" |
| IT | ISMP lists IT as error-prone: intrathecal may be mistaken as intratracheal, intratumor, intratympanic, or inhalation therapy. | Write "intrathecal" |
| OS | Can be mistaken for AS (left ear) | Write "left eye" |
| OD | Can be mistaken for AD (right ear) or "overdose" | Write "right eye" |
| OU | Can be mistaken for AU (both ears) | Write "both eyes" |
| D/C | Ambiguous - can mean either discharge or discontinue medications | Write "discharge" or "discontinue" |
| HS | ECRI/ISMP 2024 update notice says not to use HS to mean at bedtime; HS may also be used locally for half-strength, so the intended meaning should be written out. | Use "QHS" or "qhs" for bedtime; write "half-strength" when that is intended |
| hs | Can be mistaken for "half-strength" | Write "at bedtime" |
| SC | Can be mistaken for "SL" (sublingual) or "5C" (five doses) | Write "SUBQ" or "subcutaneous" |
| SQ | Can be mistaken for "5Q" (every 5 hours) or "SL" | Write "SUBQ" or "subcutaneous" |
| sq | ISMP lists sq as error-prone: subcutaneous may be mistaken as SL/sl (sublingual). | Write "SUBQ" or "subcutaneous" |
| sub q | ISMP lists sub q as error-prone: the q may be mistaken as "every". | Write "SUBQ" or "subcutaneous" |
| TIW | Can be mistaken for "three times a day" or "twice weekly" | Write "3 times weekly" |
| tiw | ISMP lists tiw as error-prone: it may be mistaken as three times a day or twice weekly. | Write "3 times weekly" |
| BIW | Can be mistaken for "twice daily" | Write "twice weekly" |
| biw | ISMP lists biw as error-prone: it may be mistaken as twice daily. | Write "twice weekly" |
| ss | Can be mistaken for "55" | Write "one-half" or "1/2" |
| SSI | ISMP flags SSI as error-prone: sliding scale insulin may be mistaken as Strong Solution of Iodine (Lugol's), and SSRI/SSI may also be confused. | Write "sliding scale insulin" |
| > | Can be mistaken for "7" or the letter "L" | Write "greater than" |
| < | Can be mistaken for "4" or the letter "L" | Write "less than" |
| @ | Can be mistaken for "2" | Write "at" |
| & | Can be mistaken for "2" | Write "and" |
| + | Can be mistaken for "4" | Write "plus" or "positive" |
| per os | Can be mistaken for "OS" (left eye) | Write "PO", "by mouth", or "orally" |
| Qn | ISMP lists Qn as error-prone: it may be mistaken as qh (every hour). | Use "QHS" or "qhs" for bedtime |
| Qhs | ISMP lists Qhs as error-prone: it may be mistaken as qhr (every hour). | Use "QHS" or "qhs" for bedtime |
| o.d. | ISMP lists o.d./OD as error-prone when intended as once daily: it may be mistaken as right eye, leading to oral liquid medications administered in the eye. | Write "daily" |
| OD | ISMP lists OD/o.d. as error-prone when intended as once daily: it may be mistaken as right eye, leading to oral liquid medications administered in the eye. | Write "daily" |
| q6PM | ISMP lists q6PM, etc. as error-prone: every evening at 6 PM may be mistaken as every 6 hours. | Write "daily at 6 PM" or "6 PM daily" |
| q1d | ISMP lists q1d as error-prone: daily may be mistaken as qid (four times daily). | Write "daily" |
| qPM | Can be read as every PM or misread | Write "daily in the evening" |
| UD | ISMP lists UD as error-prone: as directed may be mistaken as unit dose. | Write "as directed" |
| BBA | ISMP lists BBA as error-prone: the B may be mistaken as twin B rather than gender. | Use mother's last name, baby gender, and a distinguishing multiple-birth identifier |
| BGB | ISMP lists BGB as error-prone: the final B may be mistaken as gender boy rather than twin B. | Use mother's last name, baby gender, and a distinguishing multiple-birth identifier |
| IJ | ISMP lists IJ as error-prone: injection may be mistaken as IV or intrajugular. | Write "injection" |
| OJ | ISMP lists OJ as error-prone: orange juice may be mistaken as OD or OS, and drugs meant for orange juice may be given in the eye. | Write "orange juice" |
| mg. | ISMP lists periods after abbreviations as error-prone: the terminal period after mg may be mistaken as the number 1. | Write "mg" without a terminal period |
| mL. | ISMP lists periods after abbreviations as error-prone: the terminal period after mL may be mistaken as the number 1. | Write "mL" without a terminal period |
| AZT | ISMP lists AZT as error-prone: zidovudine may be mistaken as azithromycin, azathioprine, or aztreonam. | Write "zidovudine" |
| CPZ | ISMP lists CPZ as error-prone: prochlorperazine may be mistaken as chlorpromazine. | Write "prochlorperazine" or "Compazine" |
| HCT | ISMP lists HCT as error-prone: hydrocortisone may be mistaken as hydrochlorothiazide. | Write the complete drug name |
| HCTZ | ISMP lists HCTZ as error-prone: hydrochlorothiazide may be mistaken as hydrocortisone. | Write "hydrochlorothiazide" |
| MTX | ISMP lists MTX as error-prone: methotrexate may be mistaken as mitoxantrone. | Write "methotrexate" |
| PIT | ISMP lists PIT as error-prone: Pitocin may be mistaken as Pitressin, a discontinued vasopressin brand still referred to as PIT. | Write "oxytocin" or the complete drug name |
| PNV | ISMP lists PNV as error-prone: prenatal vitamins may be mistaken as penicillin VK. | Write "prenatal vitamins" |
| PTU | ISMP lists PTU as error-prone: propylthiouracil may be mistaken as Purinethol (mercaptopurine). | Write "propylthiouracil" |
| TAC | ISMP lists TAC/tac as error-prone: triamcinolone and tacrolimus may be confused with each other or with other TAC drug/regimen meanings. | Write the complete drug name |
| tac | ISMP lists TAC/tac as error-prone: triamcinolone and tacrolimus may be confused with each other or with other TAC drug/regimen meanings. | Write the complete drug name |
| TNK | ISMP lists TNK as error-prone: TNKase may be mistaken as TPA. | Write the complete drug name |
| TPA | ISMP lists TPA/tPA as error-prone: tissue plasminogen activator may be mistaken as TNK, TXA, or another tissue plasminogen activator. | Write the complete drug name |
| tPA | ISMP lists TPA/tPA as error-prone: tissue plasminogen activator may be mistaken as TNK, TXA, or another tissue plasminogen activator. | Write the complete drug name |
| TXA | ISMP lists TXA as error-prone: tranexamic acid may be mistaken as TPA. | Write "tranexamic acid" |
| Nitro drip | ISMP lists Nitro drip as error-prone: nitroglycerin infusion may be mistaken as nitroprusside infusion. | Write "nitroglycerin infusion" |
| IV vanc | ISMP lists IV vanc as error-prone: intravenous vancomycin may be mistaken as Invanz. | Write "intravenous vancomycin" |
| Levo | ISMP lists Levo as error-prone: levofloxacin may be mistaken as Levophed (norepinephrine). | Write "levofloxacin" |
| Neo | ISMP lists Neo as error-prone: Neo-Synephrine may be mistaken as neostigmine. | Write "phenylephrine" or the complete drug name |
| T3 | ISMP lists T3 as error-prone when used for Tylenol with codeine No. 3: it may be mistaken as liothyronine, which is sometimes referred to as T3. | Write "Tylenol with codeine No. 3" or "liothyronine" in full |
| APAP | ISMP lists APAP as error-prone: it may not be recognized as acetaminophen. | Write "acetaminophen" |
| SSRI | ISMP flags SSRI/SSI as error-prone: sliding scale regular insulin may be mistaken as selective serotonin reuptake inhibitor. | Write "sliding scale insulin" or spell out the antidepressant class fully |
| PCA | ISMP lists PCA as error-prone when intended as procainamide: it may be mistaken as patient-controlled analgesia. | Write "procainamide" or "patient-controlled analgesia" in full |
TermDecode is a study reference for medical terminology and abbreviation safety, not clinical guidance. Risk notes and safer alternatives are reproduced from published ISMP, Joint Commission and ECRI lists; the citation for each entry is on its own abbreviation page.
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