Dangerous Medical Abbreviations: The Australian Do Not Use List

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Australian hospital nurse double-checking a medication chart against an electronic prescribing system, illustrating safe medicines documentation practice

Patient Safety Reference

Dangerous Medical Abbreviations: The Australian Do Not Use List

Some medical abbreviations are banned in Australian healthcare because they have caused medication errors, including patient deaths. The Australian Commission on Safety and Quality in Health Care (ACSQHC) maintains the national reference for this. The 2024 update of the Recommendations for Safe Use of Medicines Terminology lists abbreviations and symbols that should never be used in handwritten, printed, electronic or verbal communication about medicines, with safer alternatives for each.

This guide explains why certain abbreviations are dangerous, walks through the Australian do not use list by category, and gives the recommended replacement for each one. It is built from ACSQHC guidance and the related NSW Health Medication Handling policy (PD2013_043), with international reference to the ISMP List of Error-Prone Abbreviations where AU guidance points to the same conclusion. For exact current wording, always check the live ACSQHC document at safetyandquality.gov.au.

Why some abbreviations cause patient harm

Medication errors are one of the most common causes of preventable harm in healthcare. Australian and international research has consistently traced a portion of those errors back to the same set of unclear, ambiguous or easily-misread abbreviations. The risks fall into a few patterns.

  • Look-alike characters. A handwritten U for units can be misread as a zero. 1.0 mg can be misread as 10 mg if the decimal point is faint. .5 mg can be misread as 5 mg if the leading zero is missing. Each of these is a tenfold dose error in the making.
  • Look-alike abbreviations. IU for international units is regularly misread as IV (intravenous). q.d. for once daily is regularly misread as q.i.d. for four times daily. The two pairs sit one stroke of the pen apart.
  • Drug-name shorthand. MS can mean morphine sulfate or magnesium sulfate, which are very different drugs at very different doses. HCT and HCTZ can both mean hydrochlorothiazide, but HCT is also a common pathology abbreviation for haematocrit.
  • Latin frequency confusion. The Latin frequency abbreviations (q.d., q.o.d., q.h.s., OD) sit at the heart of multiple high-profile error reports internationally. The 2024 ACSQHC update recommends English equivalents in most situations, particularly digital records.

The pattern is not that these abbreviations are wrong in intent. They are short forms that have been used in medical practice for decades, sometimes centuries. The problem is that the conditions of modern Australian healthcare (multi-clinician handovers, mixed handwritten and digital records, tight time pressures, look-alike or sound-alike drug pairs) make them unreliable. When a single misread abbreviation can change a dose by a factor of ten or change the drug entirely, the safer choice is to write it in full.

The Australian context: ACSQHC and NSQHS guidance

Australia has had a national reference for safe medicines terminology since 2008. The Australian Commission on Safety and Quality in Health Care first endorsed a national standard prepared by the NSW Therapeutic Advisory Group, then formalised it as the Recommendations for Terminology, Abbreviations and Symbols Used in Medicines Documentation. The most recent revision, published in 2024, is titled Recommendations for Safe Use of Medicines Terminology and is the document Australian health services should be using as the current reference.

Two practical points sit underneath the document.

  • It applies everywhere. The recommendations cover handwritten, pre-printed, digitally generated and verbal communication about medicines. They apply across hospitals, day procedure services, residential aged care, GP practices, community pharmacy and any context where medicines are prescribed, dispensed or administered.
  • It is reinforced by state policy. NSW Health Policy Directive PD2013_043 (Medication Handling in NSW Public Health Facilities) requires health services to use the endorsed standard prescribing terminology and abbreviations consistent with the ACSQHC recommendations. Equivalent guidance applies in other states, and adherence is checked under the National Safety and Quality Health Service (NSQHS) Standards, particularly Standard 4 (Medication Safety).
  • The 2024 update reflects the digital shift. The most important change between the 2016 and 2024 versions is a stronger preference for full words rather than abbreviations in digital displays, where there is no longer a space-saving reason to abbreviate. Abbreviations remain acceptable in narrow circumstances (small-screen devices, certain charting contexts) but the default in new electronic medication records is to spell things out.

Six best-practice principles sit at the head of the ACSQHC document. They are worth memorising as the rules of thumb that drive every entry in the do not use list below.

Six best-practice principles (ACSQHC, 2024)

Principle What it means in practice
Use plain language Write English words rather than Latin or apothecary abbreviations wherever there is room.
Write or display all characters clearly Legibility is part of safety. Cramped or ambiguous handwriting is a risk on its own, before any abbreviation is considered.
Write instructions and routes in full “Subcutaneous” rather than SC or SQ. “Intravenous” rather than IV in narrative text. “Right eye” rather than OD.
Use active ingredient names Generic name is preferred over brand. Drug-name abbreviations (MS, MSO4, MgSO4) are not acceptable.
Use mixed-case “tall man” lettering for look-alike, sound-alike pairs For example, vinBLAStine vs vinCRIStine, or hydrOXYzine vs hydrALAzine, to make the difference visible at a glance.
Express the dose preferably as whole numbers Reduces decimal-point errors. Use 500 mg rather than 0.5 g where possible. Always include a leading zero (0.5 mg, never .5 mg). Never include a trailing zero (5 mg, never 5.0 mg).

Drug-name confusables: the most dangerous category

Abbreviations of drug names are the highest-risk category in the do not use list. The ACSQHC position is clear: do not abbreviate drug names. Use the active ingredient name in full, every time, on every prescription, dispensing label, administration record, discharge summary and verbal handover.

The risk is not theoretical. Each of the abbreviations in the table below has been linked to documented medication errors in Australian or international reporting. The drug pairs they confuse are wildly different in dose, indication and toxicity profile.

Drug-name abbreviations to never use

Do not write Confused with Risk Write instead
MS Morphine sulfate or magnesium sulfate Two completely different drugs. Morphine is an opioid analgesic; magnesium sulfate is an electrolyte and tocolytic. Doses, routes and indications all differ. morphine OR magnesium sulfate (in full)
MSO4 Morphine sulfate Confused with MgSO4 (magnesium sulfate). Same MS confusion as above, with chemical-formula veneer that makes it look authoritative. morphine
MgSO4 Magnesium sulfate Confused with MSO4 (morphine sulfate). magnesium sulfate
HCT Hydrochlorothiazide Also used as a pathology abbreviation for haematocrit. Two unrelated meanings. hydrochlorothiazide
HCTZ Hydrochlorothiazide Misread as hydrocortisone. Different drug class, different uses, different doses. hydrochlorothiazide
AZT Zidovudine (an antiretroviral) Misread as azathioprine (an immunosuppressant) or aztreonam (an antibiotic). zidovudine
HCl Hydrochloric acid (a salt form, e.g. metformin HCl) Misread as potassium chloride. hydrochloride (when noting salt form), or write the drug in full
Nitro drip Glyceryl trinitrate infusion Confused with sodium nitroprusside infusion. Different dose ranges, different indications. glyceryl trinitrate infusion
Norflox Norfloxacin Risk of confusion with other fluoroquinolones (e.g. ofloxacin). Use the full name on every prescription. norfloxacin
T3 Triiodothyronine (a thyroid hormone) Misread as Tylenol with codeine #3 (an analgesic). liothyronine OR the analgesic written in full

Patient safety reminder. Drug-name abbreviation is one of the few categories where ACSQHC guidance is absolute, not contextual. Do not abbreviate drug names anywhere in the medicine pathway: not in prescriptions, not in handover notes, not in dispensing systems, not in patient education leaflets. Use the active ingredient name in full.

Dose unit abbreviations to avoid

Dose unit abbreviations are the next-largest source of medication error. They are also the easiest to fix, because the safe alternative is just the word in full. The classic offender, a handwritten U for units misread as a zero, has caused thousands of documented tenfold insulin overdoses internationally and is at the top of every safety body’s do not use list.

Dose unit abbreviations

Do not write Intended meaning Risk Write instead
U or u Units Misread as a zero, a four, or as cc. A handwritten “10U” can become “100” instantly. units (in full)
IU International units Misread as IV (intravenous) or as the number 10. international units (in full)
cc Cubic centimetres Misread as U (units). Also outdated terminology in metric medicines documentation. mL (millilitres)
μg or ug Microgram Greek mu often misread as m, giving mg (milligrams), a thousandfold dose error. microgram (in full) OR mcg (acceptable in narrow contexts)
ng Nanogram Acceptable in some pathology contexts but easily misread on prescriptions. nanogram (in prescribing)
oz, dr, gr, gtt Apothecary symbols (ounce, dram, grain, drops) Pre-metric. Unfamiliar to most modern Australian clinicians and pharmacists. Use metric units (mg, mL) in all medicines documentation
% Percent Generally acceptable for solution strength but should sit alongside the absolute amount where possible (e.g. lidocaine 1% (10 mg/mL)). State the absolute amount as well as the percent
x3d For three days Misread as three doses, or as a frequency. for three days (in full)

The microgram problem deserves a moment of focus. The Greek letter mu (μ) prefacing a “g” was the historical chemistry shorthand for microgram. In handwritten prescriptions, the mu loop closes and the symbol reads as a small “m”. Reading “mg” instead of “μg” turns a 25 microgram dose into a 25 milligram dose. ACSQHC guidance is to write microgram in full where there is space, and to permit “mcg” only where space is genuinely tight.

Frequency and route abbreviations

Frequency and route abbreviations are where Latin tradition collides with modern safety thinking. Many of these have been used in medicine since the 18th century. Several remain acceptable in Australian practice (TDS for three times daily, BD for twice daily, PRN for as required), but a specific subset have been linked to documented errors and are now on the do not use list. The 2024 ACSQHC update broadened the preference for English equivalents, particularly in digital records.

Frequency abbreviations to avoid

Do not write Intended meaning Risk Write instead
QD or q.d. Once daily (Latin quaque die) Misread as QID (four times daily). The “i” in “qid” is a single dot, easily confused with a poorly-formed period. once daily (or daily)
QOD or q.o.d. Every other day (Latin quaque other die) Misread as QD (once daily) or QID (four times daily). every other day OR every second day
QHS or q.h.s. At bedtime (Latin quaque hora somni) Misread as “every hour” (q.h.). at bedtime (or at night)
HS At bedtime (hora somni) Misread as half-strength. at bedtime
OD Once daily (omni die) OR right eye (oculus dexter) Two completely different meanings. The right-eye usage is also on the route do-not-use list. once daily OR right eye, depending on context
TIW or t.i.w. Three times a week Misread as three times a day or twice weekly. three times a week (specifying the days)
SID Once daily (veterinary origin) Not used in human medicine in Australia. Misread as variants of the above. once daily

Route abbreviations to avoid

Do not write Intended meaning Risk Write instead
SC or SQ Subcutaneous SC misread as SL (sublingual). SQ misread as 5Q (every). subcutaneous (in full); subcut is acceptable on Australian charts
OD, OS, OU Right eye, left eye, both eyes (Latin oculus dexter, sinister, uterque) Misread as the once-daily abbreviation, or as ear-route abbreviations (AD, AS, AU). right eye, left eye, both eyes
AD, AS, AU Right ear, left ear, both ears (Latin auris dextra, sinistra, utraque) Misread as the eye-route abbreviations or as OD/OS/OU. right ear, left ear, both ears
IN Intranasal Misread as IM (intramuscular). intranasal
IT Intrathecal Misread as IM, IV, intratracheal. The intrathecal route is high-risk; misadministration of vincristine intrathecally has caused multiple deaths internationally. intrathecal
per os By mouth The slash in “per os” is misread as a one. Also, the abbreviation PO can be misread as PR (per rectum) or BO (bowels open). oral or by mouth

Patient safety reminder. The intrathecal-route distinction is the highest-stakes single example in this section. Multiple international fatalities have occurred when intrathecal chemotherapy was given intravenously or vice versa, often anchored by ambiguous abbreviation use. ACSQHC and ISMP both recommend the route be written in full on every order for intrathecal medicines.

Decimal pitfalls: trailing zeros and naked decimals

Decimal-point errors are a tenfold dose risk and they are the easiest to prevent. Two rules cover almost every decimal-related medicines documentation error reported in Australia.

  • Always use a leading zero for doses less than 1. Write 0.5 mg, never .5 mg. A naked decimal point ahead of a 5 can be missed entirely, turning 0.5 mg into 5 mg, a tenfold overdose.
  • Never use a trailing zero on whole-number doses. Write 5 mg, never 5.0 mg. A faint decimal point in 5.0 mg can be missed, turning the dose into 50 mg.
  • Prefer whole numbers where possible. Write 500 mg rather than 0.5 g. Write 50 mcg rather than 0.05 mg. Whole numbers leave no decimal to lose.
  • Insert a space between the number and the unit. Write 5 mg, not 5mg. The unit can run into the digit when handwritten or in cramped electronic displays.

Decimal expressions: do not write versus write

Do not write Risk Write instead
.5 mg Decimal point missed; read as 5 mg. 0.5 mg
5.0 mg Decimal point missed; read as 50 mg. 5 mg
0.50 mg Trailing zero risks misreading as 0.5 mg with the zero added, or 50 mg if both decimals are missed. 0.5 mg
5mg (no space) Number and unit run together. Five with a small “m” can read as 5m, then 5 milligrams becomes 5 milligrams or 5 millimoles. 5 mg
2 1/2 tablets The fraction is misread as 21 or 212. 2.5 tablets OR two and a half tablets
1,000 mg (with comma) The comma is read as a decimal point in some international contexts. 1000 mg (no comma) OR 1 g where it gives a whole number

Latin abbreviations: replace with English

Most Latin frequency abbreviations remain in everyday Australian use, but a steady migration toward English equivalents has been underway since 2008. The 2024 ACSQHC update accelerates that shift, particularly for digital medication records where there is no longer any space-saving justification for Latin shorthand.

The Latin frequency abbreviations that are still commonly accepted in Australian charting (BD, TDS, QID, PRN) are documented in our guide to common abbreviations. The table below covers the Latin abbreviations that should NOT be used, even where they remain in older textbooks or international references.

Latin abbreviations replaced by English

Latin abbreviation Latin original Use this English term instead
q.d. quaque die once daily (or daily)
q.o.d. quaque other die every other day OR every second day
q.h.s. quaque hora somni at bedtime
h.s. hora somni at bedtime
o.d. omni die / oculus dexter once daily OR right eye
o.s. oculus sinister left eye
o.u. oculus uterque both eyes
a.d. auris dextra right ear
a.s. auris sinistra left ear
a.u. auris utraque both ears
per os by mouth oral OR by mouth
ut dict. ut dictum (as directed) as directed
s.o.s. si opus sit (if there is need) as required (or PRN where it remains acceptable)
n.r. non repetatur (do not repeat) do not repeat
aa ana (of each) of each

The Latin abbreviations that remain accepted in Australian practice (BD, TDS, QID, PRN, mane, nocte, stat) are short, familiar across the entire workforce, and have not been linked to documented error patterns. They are not on the do not use list. The discriminator is whether the abbreviation introduces ambiguity, not whether it is Latin.

What to use instead: a quick replacement checklist

Every entry on the do not use list has a defensible safer alternative. The pattern is consistent: where there is room, write it in full; where space is genuinely tight, use the safest accepted abbreviation; never abbreviate drug names; never abbreviate routes that carry high-risk consequences if confused (intrathecal, intravenous, intramuscular).

  • For drug names, write the active ingredient in full. Use Tall Man lettering for look-alike pairs (vinBLAStine vs vinCRIStine, hydrOXYzine vs hydrALAzine).
  • For dose units, write units, international units and microgram in full. Avoid U, IU, ug and the mu symbol entirely.
  • For frequencies, write the English term for any abbreviation outside the accepted Australian set. Specifically: write once daily, every other day, at bedtime, three times a week.
  • For routes, write subcutaneous, intrathecal, intranasal in full. Use the accepted Australian short forms (PO, IV, IM, PR, NG) only where the chart context makes them unambiguous.
  • For decimals, lead with zero on doses less than 1, never trail with zero on whole numbers, prefer whole numbers wherever possible, leave a space between number and unit.
  • For body sites, write right eye, left eye, both eyes, right ear, left ear, both ears in full. Eye and ear abbreviations are particularly easy to confuse with each other and with the once-daily abbreviation.

Two other patterns are worth knowing.

The Australian Pharmaceutical Formulary and the National Inpatient Medication Chart both reflect the ACSQHC recommendations. If you are looking at a chart format and wondering whether an abbreviation is acceptable, those documents are useful secondary references.

For coders, transcriptionists and quality auditors specifically, the abbreviation question matters in a slightly different way. You are not the prescriber, but you are reading what others have written. Recognising a do not use abbreviation in a record is a quality flag for clinical documentation review. Our top-100 terms cheat sheet and the prefixes and suffixes reference are the day-to-day reading tools; this article is the patient-safety lens that sits behind them.

Where this fits in the BSBMED301 unit

Safe terminology and abbreviation use is part of every medical-terminology learning pathway in Australia, including TalentMed’s BSBMED301 Interpret and Apply Medical Terminology Appropriately. The unit covers anatomy and physiology vocabulary, prefixes, suffixes, body-system terms and abbreviations, with practical work on reading clinical records accurately and writing safe documentation.

If you are training for a role in clinical coding, medical transcription, practice management or quality auditing, do not use list awareness is part of professional fluency. Knowing why a record uses “0.5 mg” rather than “.5 mg”, or “subcutaneous” rather than “SC”, is part of the literacy that lets you read past the structure to the clinical meaning of the note.

For the deeper terminology fundamentals, see the medical terminology hub. For how Australian abbreviations sit alongside other terminology systems, see how to learn medical terminology and the Greek and Latin roots reference. The BSBMED301 course page has the full unit detail and current pricing.

Frequently asked questions

The Australian Commission on Safety and Quality in Health Care recommendations are guidance rather than legislation, but they are operationalised through state and territory policy directives (such as NSW Health PD2013_043) and through the National Safety and Quality Health Service Standards. Health services accredited under the NSQHS Standards must demonstrate that medicines documentation is safe, and adherence to the ACSQHC recommendations is the practical benchmark for that. Individual prescribers carry professional responsibility for safe documentation as part of their AHPRA registration.
Yes. BD, TDS, QID and PRN remain accepted in Australian medication charting. They are short, familiar across the entire workforce and have not been linked to documented error patterns. The do not use list targets specific abbreviations that have caused harm, not Latin abbreviations as a whole. The 2024 ACSQHC update encourages English equivalents in digital displays where space allows, but the accepted short forms remain valid in handwritten charting and on small-screen devices.
The Institute for Safe Medication Practices (ISMP) list is a US reference, originally developed in the late 1990s and updated regularly. The ACSQHC list is the Australian national reference, first published in 2008 and updated in 2016 and 2024. The two lists overlap heavily because the underlying error patterns are universal. The ACSQHC list is the document Australian health services should use, with ISMP as a useful international cross-reference.
Microgram has two abbreviation traps stacked on top of each other. The Greek mu symbol (μ) is misread as a Latin “m”, so μg becomes mg, a thousandfold dose error. The lowercase “ug” looks like “mg” if the u is not crossed clearly. ACSQHC guidance is to write microgram in full where there is space, with mcg permitted only where space is tight. Never use μg or ug in handwritten or printed Australian medicines documentation.
Brand names that include MS as part of the trade mark (such as MS Contin, the slow-release oral morphine product) are acceptable when written in full as the registered brand name. The risk in the do not use list is the abbreviation MS standing alone for “morphine sulfate” or “magnesium sulfate”. If the brand product is intended, write the brand name in full. If the active ingredient is intended, write morphine in full.
Yes, but as a quality and safety conversation rather than a pedantic one. The framing that lands best clinically is patient-focused: this abbreviation has been linked to documented errors, the safer alternative is X, would you mind writing it that way going forward. Most clinicians take that framing well. If a pattern persists, the right escalation is to the unit’s medication safety lead or the hospital’s medication safety committee, who own the local audit and education programs.
The Australian Commission on Safety and Quality in Health Care website (safetyandquality.gov.au) hosts the current Recommendations for Safe Use of Medicines Terminology. Search for “recommendations for safe use of medicines terminology” or navigate to the medication safety section. The 2024 update is the most recent version. State health departments also publish localised guidance: NSW Clinical Excellence Commission, SA Health Medication Terminology, and Western Australia Country Health Service all maintain summaries on their websites.
Yes. The 2024 ACSQHC update specifically broadened the recommendations to digital displays. Electronic medication management systems should default to full words rather than abbreviations, with exceptions only for narrow contexts such as small-screen devices. The general principle is that the rationale for abbreviating medicines documentation (saving handwriting time) does not apply to text generated by an electronic system, so the safe default is to spell things out.
Yes. The ACSQHC recommendations apply across every setting where medicines are prescribed, dispensed or administered. GP practices, community pharmacies, residential aged care, day procedure services and home-based palliative care are all in scope. The state policy directives that operationalise the recommendations apply to public health facilities, but the underlying patient-safety principle is universal.

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