Download: ISMP's List of Error-Prone Abbreviations, Symbols, and Dose Designations
The abbreviations, symbols, and dose designations found in this table have been reported to ISMP through the USP-ISMP Medication Error Reporting Program as being frequently misinterpreted and involved in harmful medication errors. They should NEVER be used when communicating medical information. This includes internal communications, telephone/verbal prescriptions, computer-generated labels, labels for drug storage bins, medication administration records, as well as pharmacy and prescriber computer order entry screens. The Joint Commission (TJC) has established a National Patient Safety Goal that specifies that certain abbreviations must appear on an accredited organization's do-not-use list; we have highlighted these items with a double asterisk (**). However, we hope that you will consider others beyond the minimum TJC requirements. By using and promoting safe practices and by educating one another about hazards, we can better protect our patients.
| 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" and "discontinue" |
| IJ | Injection | Mistaken as "IV" or "intrajugular" | Use "injection" |
| IN | Intranasal | Mistaken as "IM" or "IV" | Use "intranasal" or "NAS" |
| HS hs |
Half-strength At bedtime, hours of sleep |
Mistaken as bedtime 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., especially if the period after the "q" or the tail of the "q" is misunderstood as an | Use "daily" |
| qhs | Nightly at bedtime | Mistaken as "qhr" or every hour | Use "nightly" |
| qn | Nightly or 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 6 PM | Mistaken as every 6 hours | Use "6 PM nightly" or "6 PM daily" |
| SC, SQ, sub q | Subcutaneous | SC mistaken as SL (sublingual); SQ mistaken as "5 every;" the "q" in "sub q" has been mistaken as "every" (e.g., 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 SSI |
Sliding scale regular insulin Sliding scale insulin |
Mistaken as selective-serotonin reuptake inhibitor Mistaken as Strong Solution of Iodine (Lugol's) |
Spell out "sliding scale (insulin)" |
| i/d | One daily | Mistaken as "tid" | 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 the number 0 or 4, causing a 10-fold overdose or greater (e.g., 4U seen as "40" or 4u seen as "44"); mistaken as "cc" so dose given in volume instead of units (e.g., 4u seen as 4cc) | Use "unit" |
| Dose Designations and Other Information | Intended Meaning | Misinterpretation | Correction |
|---|---|---|---|
| Trailing zero after decimal point (e.g., 1.0 mg)** | 1 mg | Mistaken as 10 mg if the decimal point is not seen | Do not use trailing zeros for doses expressed in whole numbers" |
| Dose Designations and Other Information | Intended Meaning | Misinterpretation | Correction |
|---|---|---|---|
| Drug name and dose run together (especially problematic for drug names that end in "l" such as Inderal40 mg; Tegretol300 mg) | Inderal 40 mg Tegretol 300 mg |
Mistaken as Inderal 140 mg Mistaken as Tegretol 1300 mg |
Place adequate space between the drug name, dose, and unit of measure |
| Numerical dose and unit of measure run together (e.g., 10mg, 100mL) | 10 mg 100 mL |
The "m" is sometimes mistaken as a zero or two zeros, risking a 10- to 100-fold overdose | Place adequate space between the dose and unit of measure |
| Abbreviations such as mg. or mL. with a period following the abbreviation | mg mL |
The period is unnecessary and could be mistaken as the number 1 if written poorly | Use mg, mL, etc. without a terminal period |
| Large doses without properly placed commas (e.g., 100000 units; 1000000 units) | 100,000 units 1,000,000 units |
100000 has been mistaken as 10,000 or 1,000,000; 1000000 has been mistaken as 100,000 | Use commas for dosing units at or above 1,000, or use words such as 100 "thousand" or 1 "million" to improve readability |
| Drug Name Abbreviations | Intended Meaning | Misinterpretation | Correction |
|---|---|---|---|
| ARA A | vidarabine | Mistaken as cytarabine (ARA C) | Use complete drug name |
| AZT | zidovudine (Retrovir) | Mistaken as azathioprine or aztreonam | Use complete drug name |
| CPZ | Compazine (prochlorperazine) | Mistaken as chlorpromazine | Use complete drug name |
| DPT | Demerol-Phenergan-Thorazine | Mistaken as diphtheria-pertussis-tetanus (vaccine) | Use complete drug nam |
| DTO | Diluted tincture of opium, or deodorized tincture of opium (Paregoric) | Mistaken as tincture of opium | Use complete drug name |
| HCl | hydrochloric acid or hydrochloride | Mistaken as potassium chloride (The "H" is misinterpreted as "K") |
Use complete drug name unless expressed as a salt of a drug |
| HCT | hydrocortisone | Mistaken as hydrochlorothiazide | Use complete drug name |
| HCTZ | hydrochlorothiazide | Mistaken as hydrocortisone (seen as HCT250 mg) | Use complete drug name |
| MgSO4** | magnesium sulfate | Mistaken as morphine sulfate | Use complete drug name |
| MS, MSO4** | morphine sulfate | Mistaken as magnesium sulfate | Use complete drug name |
| MTX | methotrexate | Mistaken as mitoxantrone | Use complete drug name |
| PCA | procainamide | Mistaken as patient controlled analgesia | Use complete drug name |
| PTU | propylthiouracil | Mistaken as mercaptopurine | Use complete drug name |
| T3 | Tylenol with codeine No. 3 | Mistaken as liothyronine | Use complete drug name |
| TAC | triamcinolone | Mistaken as tetracaine, Adrenalin, cocaine | Use complete drug name |
| TNK | TNKase | Mistaken as "TPA" | Use complete drug name |
| ZnSO4 | zinc sulfate | Mistaken as morphine sulfate | Use complete drug name |
| Stemmed Drug Names | Intended Meaning | Misinterpretation | Correction |
|---|---|---|---|
| "Nitro" drip | nitroglycerin infusion | Mistaken as sodium nitroprusside infusion | Use complete drug name |
| "Norflox" | norfloxacin | Mistaken as Norflex | Use complete drug name |
| "IV Vanc" | intravenous vancomycin | Mistaken as Invanz | Use complete drug name |
| Symbols | Intended Meaning | Misinterpretation | Correction |
|---|---|---|---|
  |
Dram Minim |
Symbol for dram mistaken as "3" Symbol for minim mistaken as "mL" |
Use the metric system |
| x3d | For three days | Mistaken as "3 doses" | Use "for three days" |
| > and < | Greater than and less than | Mistaken as opposite of intended; mistakenly use incorrect symbol; "< 10" mistaken as "40" | Use "greater than" or "less than" |
| / (slash mark) |
Separates two doses or indicates "per" | Mistaken as the number 1 (e.g., "25 units/10 units" misread as "25 units and 110" units) | Use "per" rather than a slash mark to separate doses |
| @ | At | Mistaken as "2" | Use "at" |
| & | And | Mistaken as "2" | Use "and" |
| + | Plus or and | Mistaken as "4" | Use "and" |
| ° | Hour | Mistaken as a zero (e.g., q2° seen as q 20) | Use "hr," "h," or "hour" |
**These abbreviations are included on TJC'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. Visit www.jointcommission.org for more information about this TJC requirement.
Permission is granted to reproduce material for internal newsletters or communications with proper attribution. Other reproduction is prohibited without written permission. Unless noted, reports were received through the USP-ISMP Medication Errors Reporting Program (MERP). Report actual and potential medication errors to the MERP via the web at www.ismp.org or by calling 1-800-FAIL-SAF(E). ISMP guarantees confidentiality of information received and respects reporters' wishes as to the level of detail included in publications.
