Dangerous Abbreviations

Health practitioners, authors, and editors must excercise due diligence in creating an abbreviation or they may cause situations similar to the ones shown below. Another possibility is not to abbreviate the phrase.

Note:  Subscribers will have access to the following information:

MedAbbrev's Do Not Use List

This table was last updated in November 2023.

Healthcare organizations are directed by the Joint Commission not to use certain abbreviations and dose designations. In Table 1 below, these are shown in red.

If you are a facility who has a multi-user site license for this website, you may show your own "Do Not Use" list to your users. Contact us.

This list shown below (Table 1) is partially based on The Institute For Safe Medication Practices list of Error-prone Abbreviations (ISMP.org)

Table 1. Dangerous abbreviations and dosage designations

Problem Term Intended Meaning Reason for Problem(s) Suggested Remedy
AU both ears Read as OU (both eyes) or not understood Use "both ears"
cc for expressing liquid measurements cubic centimeter (same as milliliter [mL]) Read as u (unit) or 00 Use "mL"
D/C discharge Interpreted as discontinue medications resulting in premature discontinuance of current medication Use "discharge"
IN intranasal Read as IV or IM or heard as IM Use "intranasal" "nasally" or use "NAS" if limited by computer space allotted
IU International unit Misread as IV (intravenous); The I is read as a one (6 IU is read as 61 units) Use "units" rather than international units, or spell out international units, using a lowercase i
IT Intrathecal
Inhalation therapy
The intended route of administration can be misinterpreted Spell out these terms
MS morphine sulfate Not understood or misunderstood Spell out these morphine sulfate
MSO4 magnesium sulfate Not understood or misunderstood Spell out-magnesium sulfate
OD once daily Interpreted as right eye Use "once daily"
OJ Orange juice Read as OS (left eye) or OD (right eye) Use "orange juice"
QOD or qod every other day Interpreted as meaning "every once a day" or read as q.i.d. (four times daily) Use "every other day"
QD or qd once daily Read or interpreted as q.i.d. (four times daily) Use "once daily"
q.n. every night Read as every hour Use "once daily at night"
q HS every night Read as every hour Use "once daily at night"
μg microgram When handwritten, misread as mg Use "mcg"
sq or sub q subcutaneous The q is read as every Use "subcut"
ss sliding scale or 1/2 Read as the numbers 55 and 1/2 Spell out "sliding scale" or "1/2"

secondary hypertension
severe hypertension
spurious hypertension
supine hypertension
systemic hypertension
systolic hypertension

The severity of the hypertension can be misinterpreted Use HTN, but spell out the specific type (e.g., systolic, secondary) instead of using the letter s
T/d (with a dot over the T) one per day Interpreted as t.i.d. (three times daily) Use "one per day"
T1D type 1 diabetes (mellitus) Read as TID (three times daily) Use DM-1
T1DM type 1 diabetes (mellitus) Read as TIDM (three times daily with meals) Use DM-1
TIW three times a week Interpreted as T/W (Tuesday & Wednesday); as twice a week; as t.i.d. (three times daily) Use "three times a week"
U unit When handwritten, read as 0, 4, 6, or cc Use "unit"
Apothecary system of measure (grains, minims, and drams) Units of measure Not understood or misunderstood Use the metric system (mg, g, mL)
Chemical symbols Drug names or laboratory tests Not understood or misunderstood Use full name except for Na, Ca, O2, K, Cl, KCl and HCl
Such as MgSO4 magnesium sulfate Not understood or misunderstood; may be read as morphine sulfate Spell out magnesium sulfate
Uncommon Latin words or phrases such as - per os By mouth Not understood or misunderstood Use by mouth, orally, or PO
ss 1/2   Use "1/2" or "one half"
UD As directed   Use "as directed"
Lettered abbreviations for drug names or drug protocols Drug names or drug protocols Not understood or misunderstood Use generic and trade name(s). Follow policy for use of protocol names in your facility.
/ (a slash mark) with, and, or per Read as one when followed by a number Use "and", "with" or "per"
Roman numerals Numbers Not understood or misunderstood (iv read as intravenous rather than 4; iii, X, L, and C, not understood) Use Arabic numerals (4, 3, 10, 50 100, etc.)
> and < "greater than" or "less than" Not understood or the meaning is reversed. Also a poorly written > (greater than) can be mistaken for the number 7. Use "greater than" or "less than"
Drug name and dosage not separated by a space Inderal 40 mg Inderal40 mg misread as Inderal 140 mg Always leave a space between a drug name, dose, and unit of measure
Trailing zeros; 1.0 mg 1 mg When handwritten decimal point is not seen; read as 10 mg causing a tenfold overdose Omit the zero; Use 1 mg (see note below)
Naked decimal point; .5 mL 0.5 mL When handwritten decimal point is not seen; read as 5 mL causing a tenfold overdose Add a zero; 0.5 mL
Abbreviated drug names A drug name Misinterpreted or not recognized Use generic or brand name
Slang (this includes unique abbreviations and symbols used in texting which would not be understood be all) communication can be offensive, insensitive, or not understood Do Not Use slang in verbal or written communications

Exception: A trailing zero may be used only where required to demonstrate the level of precision of the value being reported, such as for laboratory results, imaging studies that report size of lesions, or catheter/tube sizes. It may NOT be used in medication orders or other medication-related documentation.

Letters in Abbreviations That Should Be Used with Care

The abbreviation B for breast, brain, bone, or bladder, ex:
    BCa = breast cancer; brain cancer; bone cancer; bladder cancer

The abbreviation L for liver or lung, ex:
    LT = liver transplantation; lung transplantation

The abbreviation P for pancreatic or prostate, ex:
    PCa PCa = pancreatic cancer; prostate cancer

The abbreviation H for hand, heart, or hip, ex:
    HTx = hand transplantation; hip transplantation; heart transplantation

The abbreviation R for respiratory or renal, ex:
    RF = respiratory failure; renal failure

Examples of abbreviations that have contradictory or ambiguous meanings Top ↑

Health practitioners, authors, and editors must do due diligence in creating an abbreviation or they may cause situations similar to the ones shown below. Doing a search for the proposed abbreviation on this website, would be a good beginning. Another possibility is not to abbreviate the phrase or word.

If you have additional examples, please contact us.

Examples of abbreviations that have contradictory or ambiguous meanings
ABP ambulatory blood pressure
arterial blood pressure
ACU acute receiving unit
ambulatory care unit
ADVT acute deep venous thrombosis
asymptomatic deep venous thrombosis
AHDs antiherpetic drugs
antihypertensive drugs
AHRF acute hypoxemia respiratory failure
acute hypercapnic respiratory failure
AMI amifostine
acute mesenteric ischemia
acute myocardial infarction
APC advanced pancreatic cancer;
advanced prostate cancer
AQoL Acne Quality of Life
Assessment of Quality of Life
Asthma-related Quality of Life
Australian Quality of Life
ASHL acute sensorineural hearing loss
asymmetric sensorineural hearing loss
autoimmune sensorineural hearing loss
left ear hearing loss
ATR atropine
AZT zidovudine
BAQ Brief Aggression Questionnaire
Body Awareness Questionnaire
Buss-Perry Aggression Questionnaire
BCa bladder cancer
breast cancer
bone cancer
BDG benign gastric disease(s)
benign gynecological disease
BIQ Behavioral Inhibition Questionnaire
Behavioral Intentions Questionnaire
Body Image Questionnaire
BLC blood lactate concentration
blood lead concentration
BMRI (whole) body magnetic resonance imaging
brain magnetic resonance imaging
breast magnetic resonance imaging
BO bowel open
bowel obstruction
BPM beats per minute
breaths per minute
BR bright red
BSS Bernard-Soupier syndrome
Brown-Sequard syndrome
Brooke-Spieler syndrome
Berardinelli-Seip syndrome
blood stasis syndrome
BV betamethasone valerate
brentuximab vedotin
BVC bevacizumab
CABF carotid artery blood flow
celiac artery blood flow
cerebral arterial blood flow
coronary artery blood flow
CAS carotid artery stenosis
cerebral arteriosclerosis
coronary artery stenosis
CBS Charles Bonnet syndrome
chronic brain syndrome
corticobasal syndrome
CCF carotid cavernous Fistula
cholecystocutaneous Fistula
CESI cervical epidural steroid injection
caudal epidural steroid injection
CF cystic fibrosis
Caucasian female
calcium leucovorin (citrovorum factor)
complement fixation
cardiac failure
coronary flow
contractile force
Christmas factor
count fingers
CFIs chemotherapy-free intervals
contraceptive-free intervals
CIA chemotherapy-induced amenorrhea
chemotherapy-induced anemia
chemotherapy-induced alopecia
CINP chemotherapy-induced neuropathic pain
chronic idiopathic neck pain
CLD chronic liver disease
chronic lung disease
cholestatic liver disease
chronic lyme disease
CLOF clofarabine
CPM cyclophosphamide
chlorpheniramine maleate
CPS Chest Pain Syndrome
Chinese Paralytic Syndrome
Chronic Pain Syndrome
CPZ chlorpromazine
CRS Chinese restaurant syndrome
congenital rubella syndrome
cytokine-release syndrome
CT surgery cardiothoracic surgery
carpal tunnel surgery
CZP carbamazepine
certolizumab pegol
DAEs delayed adverse events
dermatologic adverse events (dAEs)
discontinuation due to adverse events
donor adverse events
drug adverse effects
DCd deceased
DCLD decompensated chronic liver disease
diffuse cystic lung disease
DOG delay of gratification
delusions of grandeur
DDS Denys-Drash Syndrome
dialysis disequilibrium syndrome
dopamine dysregulation syndrome
DDW deuterium-depleted water
distilled-deionized water
double-distilled water
disc'd discharged
DNR daunorubicin
did not respond
do not report
do not resuscitate
DOG delay of gratification
delusions of grandeur
DS Down Syndrome
Dravet Syndrome
DW dextrose in water
distilled water
deionized water
DXM dexamethasone
ED eating disorder(s)
elbow disarticulation
emotional disorder
erectile disfunction
EIH environmentally-induced hyperthermia
exercise-induced hypertension
exercise-induced hyperthermia
exercise-induced hypoxemia
EOP early-onset Parkinsonism
early-onset pneumonia
early-onset preeclampsia
early-onset psychosis
ERT enzyme replacement therapy
estrogen replacement therapy
ESLD end-stage liver disease
end-stage lung disease
FEC fluorouracil, epirubicin, and cyclophosphamide
fluorouracil, etoposide, and cisplatin
FSW female sex worker
field service worker
GCT germ cell tumor
giant cell tumor
granulosa cell tumor
GD Graves disease
Gaucher disease
GEM gemfibrozil;
HAO hand osteoarthritis
hip osteoarthritis
HCC Hepatocellular carcinoma
Hurthle cell carcinoma
HD Hansen disease
Hirschsprung disease
Hodgkin disease
Huntington disease
HH hypohomocysteinemia
HO hand orthosis
hip orthosis
HPW healthy pregnant women
hypertensive pregnant women
HTx hand transplantation
heart transplantation
IA intra-amniotic
IAD incontinent associated dermatitis
intractable atopic dermatitis
IAI Intra-abdominal infection
Intra-abdominal injury
IBC invasive bladder cancer
invasive breast cancer
IBV infectious bronchitis virus
influenza B virus
ICA internal carotid artery
intracranial abscess
intracranial aneurysm
I & D incision and drainage
irrigation and debridement
IHHD in-hospital hemodialysis
intensive home hemodialysis
IIH Iodine-induced hyperthyroidism
idiopathic infantile hypercalcemia
idiopathic intracranial hypertension
IPCU inpatient palliative care unit
intensive pediatric care unit
intensive psychiatric care unit
IRDM insulin-required diabetes mellitus
insulin resistant diabetes mellitus
IRF impaired renal function
Improvement in renal function
IT intrathecal
JCV John Cunningham virus
Jamestown Canyon virus
KET ketamine
KS Kawasaki Syndromee
Klinefelter Syndrome
Korsakoff Syndrome
LAM laminectomy
laparoscopic-assisted myomectomy
laser-assisted myringotomy
LAPC locally-advanced pancreatic cancer
locally-advanced prostatic cancer
LAS lactic acidosis syndrome
laxative abuse syndrome
lymphadenopathy syndrome
LB left breast
left buttock
low back
lower body
LEN lenacapavir
LF left foot
little finger
long finger
LFD lactose-free diet
low fat diet
low fiber diet
LGS leaky gut syndrome
Lennox-Gastaut syndrome
LHSH long-handled shoe horn
long-handled shower head
LKT laparoscopic kidney transplantation
liver-kidney transplantation
LL left leg
left lung
lower lid
lower limb
lower lip
LNE lymph node enlargement
lymph node excision
LNU learned nonuse (splint)
lower and upper (heard as L N U)
LOPD late-onset Parkinson disease
late-onset Pompe disease
LT liver transplantation
Lung transplantation
LTF longterm follow-up
lost to follow-up
LTFU long-term to follow-up
loss to follow-up
Ltx liver transplant
lung transplant
LVO left ventricular opacification
left ventricular output
left ventricular overactivity
MBC male breast cancer
metastatic breast cancer
MDD major depression disorder
manic depression disorder
MFS Marfan syndrome
Miller-Fisher syndrome
monofixation syndrome
MIGS micro-invasive glaucoma surgery
minimally invasive glaucoma surgery
minimally invasive gynecological surgery
MLS Maroteaux-Lamy syndrome
McLeod neuroacanthocytosis syndrome
MON Monday
MP melphalan; prednisone
mitoxantrone; prednisone
MPM malignant peritoneal mesothelioma
malignant pleural mesothelioma
MS morphine sulfate
multiple sclerosis
mitral stenosis
medical student
minimal support
muscle strength
mental status
milk shake
mitral sound
morning stiffness
MTD maximum tolerated dose
minimum toxic dose
MTZ mirtazapine
MUD marijuana use disorder
methamphetamine use disorder
MV mechanical ventilation
manual ventilation
MWS Mallory-Weiss syndrome
Mickety-Wilson syndrome
Muckle-Wells syndrome
NABS no active bowel sounds
normoactive bowel sounds
NAF Native-American female
Negro-American female
normal adult female
NBM no bowel movement
normal bowel movement
nothing by mouth
NCS nevus comedonicus syndrome
numb chin syndrome
Nutcracker syndrome
NE no effect
no enlargement
not evaluated
NITRO nitroglycerin
sodium nitroprusside
NOAC Non-vitamin k antagonist Oral AntiCoagulant(s); also defined as Novel or New
No Oral AntiCoagulant(s) or NO AntiCoagulant(s)
NRBCs (nRBCs) native red blood cells
noninfected red blood cells
nonparasitized red blood cells
normal red blood cells
nucleated red blood cells
NSAE neurosensory adverse events
nonserious adverse events
NVD neck vein distention
no venous distention
OHS obesity hypoventilation syndrome
ocular histoplasmosis syndrome
ocular hypoperfusion syndrome
OLB open-liver biopsy
open-lung biopsy
OPC operable pancreatic carcinoma
oropharynx cancer
oropharyngeal candidiasis
PAA popliteal artery aneurysm
pulmonary artery aneurysm
PAVF pial arteriovenous fistula
pulmonary arteriovenous fistula
PBL primary breast lymphoma
primary brain lymphoma
PBZ phenylbutazone
PCS pelvic congestion syndrome
post cholecystectomy syndrome
postconcussion syndrome
PCU palliative care unit
primary care unit
progressive care unit
protective care unit
PD Paget disease
panic disorder
Parkinson disease
personality disorder
Peyronie disease
PHTN portal hypertension
postpartum hypertension
primary hypertension
pediatric hypertension
pulmonary hypertension
Pit Pitocin
PLB percutaneous liver biopsy
percutaneous lung biopsy
PLNs pancreatic lymph nodes
parametrial lymph nodes
pelvic lymph nodes
popliteal lymph nodes
positive lymph nodes
pyloric lymph nodes
PMD pretomanid
PMS Phelan-McDermid Syndrome
postmenopausal syndrome
postconcussion syndrome
PNUS perineal ultrasound
peripheral nerve ultrasound
prenatal ultrasound
PNS paraneoplastic syndrome(s)
paraneoplastic neurological syndrome(s)
primary nephrotic syndrome
pudendal nerve entrapment syndrome
POMI perioperative myocardial infarction (from the time of admission to discharge)
postoperative myocardial infarction (occurring after surgery)
PORT postoperative radiotherapy
postoperative respiratory therapy
prostate-only radiotherapy
PSAH perimesencephalic subarachnoid hemorrhage
primary subarachnoid hemorrhage
pseudo subarachnoid hemorrhage
pTBI pediatric traumatic brain injury
penetrating traumatic brain injury
PTLD post-transplant lymphoproliferative disorder
post-treatment Lyme disease
post-tuberculosis lung disease
PUO pruritus of unknown origin
pyrexia of unknown origin
PVO peripheral vascular occlusion
portal vein occlusion
pulmonary venous occlusion
PWD person(s) with a disability
people with dementia
patients with diabetes
PWH patients with hemophilia
patients with HIV
QM every monday
RALP robotic-assisted laparoscopic prostatectomy
robotic-assisted laparoscopic pyeloplasty
RB right breast
right buttock
RFTs renal function test
respiratory function tests
RM radical mastectomy
reduction mammoplasty
RPBC rapidly proliferating breast cancer
receptor-positive breast cancer
RS Reiter syndrome
Rett syndrome
Reye syndrome
Richter syndrome
Rumination Syndrome
Raynaud disease (syndrome)
RT radiation therapy
recreational therapy
respiratory therapy
RTI reproductive tract infection
respiratory tract infection
RTS radial tunnel syndrome
Rothmund-Thomson syndrome
Rubinstein-Taybi syndrome
RWW raw wastewater
reclaimed wastewater
S & S swish and spit
swish and swallow
SA suicide alert
suicide attempt
SAD social anxiety disorder
seasonal affective disorder
SALF severe acute liver failure
subacute liver failure
SCAD spontaneous cervical artery dissection
spontaneous coronary artery dissection
stable coronary artery disease
SCCL solitary cerebral cysticercal lesion
squamous cell cancer-like
squamous cell carcinoma of the larynx
squamous cell carcinoma of the lung
squamous cell carcinoma of the lip
SCCP squamous cell carcinoma of the penis
small cell carcinoma of the prostate
SDBP seated, standing, or supine diastolic blood pressure
SDRT single-dose radiotherapy
seasonal affective disorder
SDS Schwann-Diamond Syndrome
somatropin deficiency syndrome
sudden death syndrome
SGAs second generation antihistamines
second generation antipsychotics
SICH spontaneous intracerebral hemorrhage
supratentorial intracerebral hematoma
symptomatic intracranial hemorrhage
SJS Schwartz-Jampel syndrome
Stevens-Johnson syndrome
Sawyer-James syndrome
SMQ science motivation questionnaire
Selective Mutism Questionnaire
Sexual Modes Questionnaire
Short-Memory Questionnaire
Social Motivation Questionnaire
Southampton Mindfulness Questionnaire
Sports Motivation Questionnaire
Standardized MedDRA Queries
States of Mind Questionnaire
SMS scalded mouth syndrome
Smith-Magenis syndrome
stiff-man syndrome
SOBT salivary occult blood test
stool occult blood test
SPT sitting pivot transfer
squat pivot transfer
standing pivot transfer
SRDs spine-related diseases
syndromic retinal disease
systemic rheumatic diseases
smoking-related diseases
stress-related diseases
substance-related diseases
SS sacral slope
saline soak
saline solution
saliva sample
serotonin syndrome
serum sickness
SSE saline solution enema
soapsuds enema
SSS scalded skin syndrome
sick sinus syndrome
subclavian steal syndrome
ST Schirmer Test
skin test
Spurling Test
stress test
STF special tube feeding
standard tube feeding
TAC tetracaine, Adrenalin, and cocaine solution
triamcinolone cream
TAMV time average maximum velocity (blood flow)
time-averaged mean velocity (blood flow)
TBA thyroid biochemical abnormalities
to be absorbed
to be added
to be administered
to be admitted
to be announced
to be arranged
to be assessed
total body (surface) area
traditional birth attendant
lamivudine (Epivir)
Tylenol with 30 mg of Codeine
T/E testosterone to epitestosterone (ratio)
testosterone to estrogen (ratio)
trunk-to-extremity skinfold thickness (index)
TICU thoracic intensive care unit
transplant intensive care unit
trauma intensive care unit
TMZ temazepam
TRZ thioridazine
TS Tay-Sachs (disease)
Tourette syndrome
Turner syndrome
TSCC thymic squamous cell carcinoma
tongue squamous cell carcinoma
tonsillar squamous cell carcinoma
tubal tubal ligation
tubal pregnancy
Tx therapist
VAC etoposide (VePesid),
cytarabine (ara-C, and carboplatin,
vincristine, dactinomycin
vincristine, doxorubicin)
VAD vincristine, doxorubicin, (Adriamycin) and dexamethasone
vincristine, doxorubicin (Adriamycin) and dactinomycin
VAP vincristine, Adriamycin, and prednisone
vincristine, Adriamycin, and procarbazine
vincristine, actinomycin D, and Platinol AQ
vincristine, asparaginase, and prednisone
VDI vitamin D insufficiency
vitamin D intoxication
WBRT whole-brain radiotherapy
whole-breast radiotherapy
WC warm compresses
wet compresses
WS Waardenburg Syndrome
Werner Syndrome
West Syndrome
Williams Syndrome
Withering syndrome
WSS White Spot Syndrome
Wiedemann-Steiner Syndrome
YOD year of death
year of diagnosis

Examples of Abbreviations That have been Misread or Misinterpreted that resulted in error Top ↑

We would appreciate receiving other examples of abbreviations that have been misinterpreted causing error or delays so that this section can be expanded - contact us.

(1) "HCT250" was intended to mean hydrocortisone 250 mg but was interpreted as hydrochlorothiazide 50 mg(HCTZ50 mg).

(2) Flucytosine was improperly abbreviated as 5 FU, causing it to be read as fluorouracil. Flucytosine is abbreviated 5 FC and fluorouracil is 5 FU.

(3) Floxuridine was improperly abbreviated as 5 FU, causing it to be read as fluorouracil. Floxuridine is abbreviated FUDR and fluorouracil is 5 FU.

(4) MTX was thought to be mechlorethamine. MTX is methotrexate and mechlorethamine is abbreviated HN2.

(5) The abbreviation "U" for unit is the most dangerous one in the book, having caused numerous tenfold insulin and heparin overdoses. The word unit should never be abbreviated. The handwritten U for unit has been mistaken for a zero, causing tenfold errors. The handwritten U for unit has also been read as the number four, six, and as "cc".

(6) OD, meant to signify once daily, has caused Lugol's solution to be given in the right eye.

(7) OJ meant to signify orange juice, looked like OS and caused saturated solution of potassium iodide to be given in the left eye.

(8) IVP, meant to signify intravenous push (Lasix 20 mg IVP), caused a patient to be given an intravenous pyelogram which is the usual meaning of the abbreviation.

(9) Na Warfarin (sodium warfarin) was read as "No Warfarin."

(10) The abbreviation "s" for "without" has been thought to mean "with" (c).

(11) The order for PT, intended to signify a laboratory test order for prothrombin time, resulted in the ordering of a physical therapy consultation.

(12) The abbreviation "TAB," meant to signify Triple Antibiotic (a coined name for a hospital sterile topical antibiotic mixture), caused patients to have their wounds irrigated with a diet soda. At another facility, with the same set of circumstances, they did not have TAB™, so they used Diet Shasta™

(13) A slash mark (/) has been mistaken for a one, causing a patient to receive a 100 unit overdose of NPH insulin when the slash was used to separate an order for two insulin doses:
6 units regular insulin/20 units NPH insulin.

(14) Vidarabine, an antiviral agent, was ordered as ara-A; however, ara-C, which is cytarabine, an antineoplastic agent, was given.

(15) On several occasions, pediatric strength diptheriatetanus toxoids (DT) have been confused with adult strength tetanus-diphtheria toxoids (Td).

(16) DTP is commonly understood to refer to diphtheria-tetanus-pertussis vaccine, but in some hospitals it is also used as shorthand for a sedative cocktail of Demerol, Thorazine, and Phenergan. Several cases have occurred where a child was vaccinated rather than given a sedative mixture.

(17) What does the abbreviation MR mean? Some will guess measles-rubella vaccine (M-R Vax II, Merck), while others will assume mumps-rubella vaccine (Blavax II, Merck).

(18) The abbreviation TIW (three times a week) was thought to mean Tuesday and Wednesday when the I was read as a slash mark. Due to confirmation bias (you see what you know), this uncommon abbreviation is seen as the more commonly used T1D (three times a day).

(19) PCA, meant to be procainamide, was interpreted as patient-controlled analgesia.

(20) PGE1 (alprostadil, Caverject) was read as P6 E1 (Alcon's ophthalmic 6% pilocarpine and 1% epinephrine solution).

(21) A nurse transcribed an oral order for the antibiotic aztreonam as AZT, which was subsequently thought to be the antiviral drug zidovudine.

(22) An order for TAC 0.1%, intended to mean triamcinolone cream, was interpreted as tetracaine, Adrenalin, and cocaine solution.

(23) An order for SPA (salt poor albumin) was overlooked because it was not recognized as a drug order.

(24) Therapy was delayed and considerable professional time was wasted when an order for
"Bactrim SS q 12 h on S/S" had to be clarified (Bactrim Single Strength every 12 hours on Saturday and Sunday).

(25) A physician wrote an order stating "may take own supply of EPO". The physician meant evening primrose oil, not Epogen (epoetin alfa).

(26) 4-MP was recommended to treat ethylene glycol poisoning. The medical resident mistakenly interpreted this as 6-MP (6-mercaptopurine). 4-MP is fomepizole (4-methylpyrazole) and 6-MP is mercaptopurine (6-mercaptopurine).

(27) An order for lomustine stated it was to be given at "hs". This was misinterpreted as to mean every night. After continuous administration, toxicity resulted in the patient's death. The drug is normally given once every 6 weeks. State complete orders such as "HS_ 1 dose today," "HS nightly," or "HS nightly PRN for sleep."

(28) The directions for an order for Cortisporin Otic Solution indicated "Three drops in R ear T1D." The patient was given the drops in the rear rather than the right ear.

(29) There have been mix-ups between IL-2 and IL-11 when IL-2 is expressed as IL-II (Roman numeral 2). The II has been read as "IL eleven," and vice versa. IL-2 (interleukin 2) is aldesleukin (Proleukin) and IL-11 is oprelvekin (Neumega).

(30) A drug was ordered "Q 10 h." It was read as QID (four times daily). Drugs should not be ordered at unusual hourly intervals such as every 10, 18, 36 hours, as this has resulted in a host of errors. Standard times are every 2, 3, 4, 6, 8, or 12 hours; once, twice, three, or four times daily; every day, or Monday, Wednesday, and Friday and once weekly.

(31) 6 IU was read as 61 units instead of the intended 6 international units.

(32) A dose of phenytoin was modified and expressed as mg/Kg/d. The d was read as "dose" rather than the intended "day" resulting in 3 extra doses being given.

(33) An order appeared as, "If no BM in PM give MOM in AM p.r.n."

(34) Sometimes ambiguous abbreviations cause financial losses to health providers. for example, an insurance provider may pay less for an office visit for mental retardation than it does for mitral regurgitation. This can happen if the coder is faced with the abbreviation MR.

(35) The abbreviation for "q PM" has been read as 9 PM (a one time dose at 9 PM) rather than every night.

(36) An order was written in a hospital, "Cortisporin 3 drops, AS bid." There was a question about the meaning of AS, but since the patient was scheduled for a colonoscopy it was decided that the meaning was anal sphincter, so the drug was administered rectally rather than in the left ear as intended. When the patient was asked to roll over for their medicine, I suppose they could have protested that there was nothing wrong with their rectum, but then again, maybe this was part of a complex preparation for their colonoscopy!

(37) A liver transplant patient on readmission had an order handwritten, "MMF 1000 mg PO BID (mycophenolate mofetil)." Mycophenolate mofetil is the immunosuppressive agent CellCept which has been abbreviated MMF. The order was misread as 1000 mg twice 1 daily MWF (Monday, Wednesday, and Friday). Several doses of this critical drug were omitted before the error was discovered.

(38) A prescription was written for PTU. PTU normally means propylthiouracil, however Purinethol was dispensed in error causing a fatality. Purinethol is never abbreviated PTU. The error probably occurred because both propylthiouracil and Purinethol are available in 50 mg tablets and sit side-by-side on the pharmacy shelf. The prescriber contributed to the error by using nonstandard terminology, an abbreviation.

(39) A nurse mistakenly administered Chloral Hydrate intravenously. This syrup is intended for oral administration only. This was done because the label contained the legend C IV. This was interpreted as intravenous when in fact, C IV stands for a class 4 controlled substance. All controlled substances are indicated as Roman numerals, I, II, III, IV, V. Even though 99.9% of nurses know that drugs in screw-capped bottles, labeled "syrup" are not intended for intravenous administration, it would pay to change C IV to C4 on drug labels.

(40) After performing spinal surgery a surgeon kept his ICU patients NPO (nothing by mouth), until they had flatus and good bowel sounds. His order was: "Strict NPO. Check BS Q2H." The patient had "blood sugar" laboratory tests drawn Q2H!

(41) An infant died when she received 5 mg of morphine instead of the prescribed ".5 mg" dose when the naked decimal point was not seen with handwritten orders. This can easily occur if the decimal point happens to fall on a line, or falls on part of a letter from the line above, or when working from poor copies of an original order. Always place a zero in front of a naked decimal (0.5 mg, not .5 mg).

(42) An order was written for Colchicine 1.0 mg IV now. The decimal point was not seen and 10 mg was administered. The patient died. This can easily occur with a handwritten order if the decimal point happens to fall on a line, or falls on part of a letter from the line above, or when working from poor copies of the original order. Use 1 mg, not 1.0 mg. A trailing zero can correctly be used where precision is being expressed, such as in reporting a laboratory value, but never in expressing a drug dose or strength.

(43) The pharmacy received an order for a diltiazem drip. No rate of administration was listed, so the pharmacist entered "125 mg UD" in computer rate field. UD is an old-time Latin abbreviation for as directed (ut dictum). The nurse did not know the classical meaning of UD and interpreted as meaning unit dose. The nurse then proceeded to give the diltiazem at 125 mg/hr and ran the entire dose over one hour (the rate should have been 5 mg/hr). The nurse then asked for another diltiazem drip and also ran that one over 1 hour. The patient expired. One of the many factors in causing this error was the use of an ancient abbreviation which should no longer be used.

(44) An order was written for lidocaine 1% S EPINEPHrine. It was misinterpret as lidocaine 1% with EPINEPHrine. S is a Latin-derived abbreviation for "without" which is rarely used. "Lidocaine 1%" is a safer way to express this order.

(45) DNR usually means, "do not resuscitate" but also has been used for the drug, daunorubicin, "do not report", and, "did not respond". We are not as yet familiar with any mix-ups, but anything can happen!

(46) An order was written, "....Patient is taking Coumadin and was placed on amiodarone. There is an interaction. Instead of adjusting coumadin dose, consider NoAC." This was interpreted to mean "no anticoagulant" rather than its intended meaning, "new [noval] oral anticoagulant[s] (rivaroxaban [Xarelto], dabigatran [Pradaxa] and apixaban [Eliquis]").

(47) An order was written," PT TO SEE PT WHEN PT WNL", which was translated as "Patient to see physical therapy when prothrombin is within normal limits" This did not cause an error, but did slow things down!

(48) In an emergency department, at physician asked the nurse to get the drug TXA. The nurse thought he said TNK. She brought the physician TNKase. The potential mistake was discovered and an error did not occurred. TXA is tranexmaic acid injection (Cykiokapron) and TNK is tenecteplase injection (TNKase).

(49) ANIN could be identified. It turned out to be a typo for two words, an in.

(50) ONJ could be identified. It turned out to be a typo for the word, on.

(51) An order for tPA (alteplase [Activase]) was thought to be TPN (total parental nutrition) causing a delay in initiating critical therapy.

(52) Due to a typo or transcription error, Dicem could not be identified. It should have been, Dycem, a nonslip material used by occupational therapists.


1. Davis NM, Cohen MR. Medication Errors; Causes and Prevention. Warminster, PA; Neil M Davis Associates; 1983.

2. Cohen MR. Medication error reports. Hosp Pharm (appears monthly from 1975 to the present).

3. Cohen MR, Medication errors. Nursing 2018 (appears monthly, starting in Nursing 77, to the present).

4. Davis NM, Med Errors. Am J Nursing (appears monthly from 1995 to 1995).

5. Cohen MR, Medication Errors. American Pharmaceutical Assoc. Wash. DC, 2007.

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