Medication Errors: Improving Practices and Patient Safety

It is widely acknowledged that medication errors result in thousands of adverse drug events, preventable reactions, and deaths per year. Nurses, physicians, pharmacists, patient safety organizations, the Food and Drug Administration, the pharmaceutical industry, Health Canada, and other parties share in the responsibility for determining how medication errors occur and designing strategies to reduce error.

One impediment to understanding the scope and nature of the problem has been the reactive "blaming, shaming, training" culture that singled out one individual as the cause of the error. Also historically, medication errors that did not result in patient harm—near-miss situations in which an error could have but didn’t happen—or errors that did not result in serious harm were not reported. In contrast, serious errors often instigated a powerful punitive response in which one or a few persons were deemed to be at fault and, as a result, lost their jobs and sometimes their licenses.

In 1999, the Institute of Medicine (IOM) published To Err Is Human: Building a Safer Health System, which drew attention to the problem of medication errors. It pointed out that excellent health care providers do make medication errors, that many of the traditional processes involved in the medication-use system were error-prone, and that other factors, notably drug labeling and packaging, contributed to error. Furthermore, the IOM report, in conjunction with other groups such as the United States Pharmacopeia and the Institute for Safe Medication Practices (ISMP), called for the redesign of error-prone systems to include processes that anticipated the fallibility of humans working within the system. This initiative is helping shift the way the health care industry addresses medication errors from a single person/bad apple cause to a systems issue.

The National Coordinating Council for Medication Error Reporting and Prevention developed the definition of a medication error that reflects this shift and captures the scope and breadth of the issue:

"A medication error is any preventable event that may cause or lead to inappropriate medication use or patient harm while the medication is in the control of the health care provider, patient, or consumer. Such events may be related to professional practice, health care products, procedures, and systems, including prescribing; order communication; product labeling, packaging, and nomenclature; compounding; dispensing; distribution; administration; education; monitoring; and use."

Inherent in this definition's mention of related factors are the human factors that are part of the medication use system. For example, a nurse or pharmacist may automatically reach into the bin where dobutamine is usually kept, see "do" and "amine," and select dopamine instead of dobutamine. Working amid distractions, working long hours or shorthanded, and working in a culture where perfection is expected and questioning is discouraged are other examples of the human factors and environmental conditions that contribute to error.

The goal for the design of any individual or hospital-wide medication use system is to determine where systems are likely to fail and to build in safeguards that minimize the potential for error. One way to begin that process is to become familiar with medications or practices that have historically been shown to be involved in serious errors.

High-Alert Medications

Some medications, because of a narrow therapeutic range or inherent toxic nature, have a high risk of causing devastating injury or death if improperly ordered, prepared, stocked, dispensed, administered, or monitored. Although these medications may not be involved in more errors, they require special attention due to the potential for serious, possibly fatal consequences. These have been termed high-alert medications, to communicate the need for extra care and safeguards. Many of these drugs are used commonly in the general population or are used frequently in urgent clinical situations. The Joint Commission monitors the use of frequently prescribed high-alert medications, which include insulin, opioids, injectable potassium chloride (or phosphate) concentrate, antithrombotics, sodium chloride solutions with a concentration greater than 0.9%, and others. Visit the Institute for Safe Medication Practices at www.ismp.org for a complete list of High-Alert Drugs.

Causes of Medication Errors

Many contributing factors and discrete causes of error have been identified, including failed communication, poor pharmaceutical supply chain distribution practices, dose miscalculations, drug packaging and drug-device related problems, incorrect drug administration, and lack of patient education.

Failed Communication:

Failed communication covers many of the errors made in the ordering phase, and although ordering is performed by the prescriber, the nurse, the clerk, and the pharmacist who interpret that order are also involved in the communication process.

Poorly handwritten or verbal orders. Handwriting is a major source of error and has led to inaccurate interpretations of the drug intended, the route of administration, the frequency, and dose. Telephone and verbal orders are likewise prone to misinterpretation. The current use of electronic drug order entry within hospitals and electronic prescribing to pharmacies contributes to increased legibility and consistency of medication orders and prescriptions.
Drugs with similar-sounding or similar-looking names. Similar sounding names, or names that look similar when handwritten, are frequently confused. Doxorubicin hydrochloride and doxorubicin liposomal, or Lunesta® and Neulasta® are two examples. Mix-ups are more likely when each drug has similar dose ranges and frequencies.

Several of the sound-alike/look-alike drugs were targeted for labeling intervention by the FDA, which requested manufacturers with look-alike names to voluntarily revise the appearance of the established names. The revision visually differentiates the drug names by using "tall man" letters (capitals) to highlight distinguishing syllables (e.g., buPROPrion versus busPIRone or ceFAZolin versus cefTAZidime. See the TALL MAN Lettering table in the Medication Safety Tools section for the list of the pairs of drugs that are commonly confused, often with serious consequences.

Misuse of zeroes in decimal numbers. Massive, tenfold overdoses are traceable to not using a leading zero (.2 mg instead of 0.2 mg) or adding an unnecessary trailing zero (2.0 mg instead of 2 mg) in decimal expressions of dose. Similar overdoses are found in decimal expressions in which the decimal point is obscured by poor handwriting, stray marks, or lined orders sheets (e.g., reading 3.1 grams as 31 grams). Underdosing also may occur by the same mechanism and prevent a desired, perhaps life-saving effect.
Misinterpreted abbreviations. Abbreviations can be misinterpreted or, when used in the dose part of the order, can result in incorrect dose of the correct medication. For example, lower- or uppercase "U" for units has been read as a zero, making 10 u of insulin look like 100 units when handwritten. The Latin abbreviation "QOD" for every other day has been misinterpreted as QID (4 times per day). Current widespread use of electronic drug ordering and prescriptions increases legibility; frequency choices are often in plain language such as "every other day" instead of "QOD." See Table 1 for a list of confusing abbreviations and safer alternatives.
Ambiguous or incomplete orders. Orders that do not clearly specify dose, route, frequency, or indication do not communicate complete information and are open to misinterpretation.

Poor Distribution Practices:

Poor distribution includes error-prone storing practices such as keeping similar-looking products next to each other. Dispensing multidose floor stock vials of potentially dangerous drugs instead of unit (single) dose vials is also associated with error, as is allowing nonpharmacists to dispense medications in the absence of the pharmacist.

Dose Miscalculations:

Dose miscalculations are a prime source of medication error. Also, many medications need to be dose-adjusted for renal or hepatic impairment, age, height and weight, and body composition (i.e., correct for obesity). Complicated dosing formulas provide many opportunities to introduce error. Often vulnerable populations, such as premature infants, children, older adults, and those with serious underlying illnesses, are at greatest risk.

Drug Packaging:

Similar packaging or poorly designed packaging encourages error. Drug companies may use the same design for different formulations or fail to highlight information about concentration or strength. Lettering, type size, color, and packaging methods can either help or hinder drug identification.

Drug Delivery Systems:

Drug delivery systems include infusion pumps and drip rate controllers. Some models do not prevent free flow of medication, leading to sudden high dose infusion of potent and dangerous medications. The lack of safeguards preventing free flow and programming errors are among the problems encountered with infusion control devices. Newer models, which are integrated with the medication administration record (MAR) via scanned barcodes to match the patient with drug, dose, and timing, contribute to increased dosing safety; however, it is a nursing responsibility to verify the dose and determine that the infusion pump is delivering properly at the point of drug administration.

Incorrect Drug Administration:

Incorrect drug administration covers many problems. Misidentification of a patient, incorrect route of administration, missed doses, or improper drug preparation are types of errors that occur during the administration phase. Barcode scanning to identify the patient and correlate with the correct MAR decreases the likelihood of incorrect drug administration.

Lack of Patient Education:

Safe medication use is enhanced in the hospital and the home when the patient is well informed. The knowledgeable patient can recognize when something has changed in their medication regimen and can question the health care provider. At the same time, many issues related to medication errors, such as ambiguous directions, unfamiliarity with a drug, and confusing packaging, affect the patient as well as the health care provider, underscoring the need for careful education. Patient education also enhances adherence, which is a factor in proper medication use.

Prevention Strategies

Since medication use systems are complex and involve many steps and people, they are error-prone. On an individual basis, nurses can help reduce the incidence of error by implementing the following strategies:

Clarify any order that is not obviously and clearly legible. Ask the prescriber to print orders using block style letters if handwritten.
Do not accept orders with the abbreviation "u" or "IU" for units. Clarify the dosage and ask the prescriber to write out the word units.
Clarify any abbreviated drug name or the abbreviated dosing frequencies q.d., QD, q.o.d., QOD, and q.i.d or QID. To minimize any confusion associated with drug names, abbreviation of drugs names should ALWAYS be avoided. Suggest abandoning Latin abbreviations in favor of spelling out dosing frequency.
Decimal point errors can be hard to see. Suspect a missed decimal point and clarify any order if the dose requires more than 3 dosing units.
If dose ordered requires use of multiple dosage units or very small fractions of a dose unit, review the dose, have another health care provider check the original order and recalculate formulas, and confirm the dose with the prescriber.
If taking a verbal order, ask prescriber to spell out the drug name and dosage to avoid sound-alike confusion (e.g., hearing Cerebyx for Celebrex, or fifty for fifteen). Read back the order to the prescriber after you have written it in the chart. Confirm and document the indication to further enhance accurate communication.
Clarify any order that does not include metric weight, dosing frequency, or route of administration.
Weigh each patient as soon as possible on admission and during each outpatient or emergency department encounter. Avoid the use of a stated, estimated, or historical weight.
Do not start a patient on new medication by borrowing medications from another patient. This action bypasses the double-check provided by the pharmacist’s review of the order.
Always check the patient's name band before administering medications. Verbally addressing a patient by name does not provide sufficient identification. If available, use of barcode scanning per institutional policy recommended.
Use the facility's standard drug administration times to reduce the chance of an omission error.
Be sure to fully understand any drug administration device before using it. This includes infusion pumps, inhalers, and transdermal patches.
Have a second practitioner independently check original order, dose calculations, and infusion pump settings for high-alert medications.
Realize that the printing on packaging boxes, vials, ampules, prefilled syringes, or any container in which a medication is stored can be misleading. Be sure to differentiate clearly the medication and the number of milligrams per milliliter versus the total number of milligrams contained within. Massive overdoses have been administered by assuming that the number of milligrams per milliliter is all that is contained within the vial or ampule. Read the label when obtaining the medication, before preparing or pouring the medication, and after preparing or pouring the medication.
Educate patients about the medications they take. Provide verbal and written instructions and ask the patient to restate important points.

RESOURCES

Billstein-Leber, M., Carrillo, C., Cassano, A. T., Moline, K., & Robertson, J. (2018). ASHP guidelines on preventing medication errors in hospitals. American Journal of Health-System Pharmacy, 75(19), 1493–1517. https://doi.org/10.2146/ajhp170811
Wang, H., Tao, D., & Yan, M. (2021). Effects of text enhancement on reduction of look-alike drug name confusion: A systematic review and meta-analysis. Quality Management in Health Care, 30(4), 233–243. https://doi.org/10.1097/qmh.0000000000000303
Institute for Safe Medication Practices. (2024). Targeted medication safety best practices for hospitals. https://www.ismp.org/guidelines/best-practices-hospitals
Kohn, L. T., Corrigan, J. M., & Donaldson, M. S. (Eds.). (1999). To err is human: Building a safer health system. National Academy Press.
Manias, E., Kusljic, S., & Wu, A. (2020). Interventions to reduce medication errors in adult medical and surgical settings: A systematic review. Therapeutic Advances in Drug Safety, 11, 2042098620968309. https://doi.org/10.1177/2042098620968309
National Coordinating Council for Medication Error Reporting and Prevention. (2025). About medication errors: What is a medication error? https://www.nccmerp.org/about-medication-errors
Hutton, K., Ding, Q., & Wellman, G. (2021). The effect of bar-coding technology on medication errors: A systematic literature review. Journal of Patient Safety, 17(3), e192–e206. https://doi.org/10.1097/pts.0000000000000366

Table 1: Abbreviations and Symbols Associated with Medication Errors

Abbreviation/Symbol	Intended Meaning	Mistaken For	Recommendation
APAP	acetaminophen	not recognized as acetaminophen	Use full drug name
AT II	angiotensin II	antithrombin III	Use full drug name
AT III	antithrombin III	angiotensin II	Use full drug name
AZT	zidovudine	azithromycin, azathioprine, aztreonam	Use full drug name
Coined names for compounded products (e.g., magic mouthwash, banana bag, GI cocktail, pink lady)	specific ingredients compounded together	mistaken ingredients	Use complete drug/product names for all ingredients
CPZ	Compazine (prochlorperazine)	chlorpromazine	Use full drug name
DOR	doravirine	Dovato (dolutegravir/lamivudine)	Use full drug name
HCT	hydrocortisone	hydrochlorothiazide	Use full drug name
HCTZ	hydrochlorothiazide	hydrocortisone	Use full drug name
IV vanc	intravenous vancomycin	Invanz (ertapenem)	Use full drug name
"Levo"	levofloxacin	Levophed (norepinephrine)	Use full drug name
MgSO₄¹	magnesium sulfate	morphine sulfate	Use full drug name
MS or MSO₄¹	morphine sulfate	magnesium sulfate	Use full drug name
MTX	methotrexate	mitoxantrone	Use full drug name
Na at the beginning of a drug name (e.g., Na bicarbonate)	sodium bicarbonate	no bicarbonate	Use full drug name
Neo	Neo-Synephrine (phenylephrine)	neostigmine	Use full drug name
"Nitro" drip	nitroglycerin infusion	nitroprusside infusion	Use full drug name
NoAC	novel/new oral anticoagulant	no anticoagulant	Use full drug name
Number embedded in drug name (e.g., 5-fluorouracil, 6-mercaptopurine)	fluorouracil or mercaptopurine	embedded number mistaken as the dose or number of tablets/capsules to be administered	Use full drug name without an embedded number
OXY	oxytocin	oxycodone, Oxycontin	Use full drug name
PCA	procainamide	patient controlled analgesia	Use full drug name
PIT	Pitocin (oxytocin)	Pitressin (vasopressin)	Use full drug name
PNV	prenatal vitamins	penicillin VK	Use full drug name
PTU	propylthiouracil	Purinethol (mercaptopurine)	Use full drug name
T3	Tylenol with codeine No. 3	Liothyronine	Use full drug name
TAC or tac	triamcinolone or tacrolimus	one mistaken for the other or as tetracaine, Adrenalin, cocaine, Taxotere, Adriamycin, or cyclophosphamide	Use full drug name
TAF	tenofovir alafenamide	tenofovir disoproxil fumarate	Use full drug name
TDF	tenofovir disoproxil fumarate	tenofovir alafenamide	Use full drug name
TNK	TNKase	TPA	Use full drug name
TPA or tPA	tissue plasminogen activator, Activase (alteplase)	TNK or TNKase (tenecteplase), TXA (tranexamic acid), Retevase (reteplase)	Use full drug name
TXA	tranexamic acid	TPA	Use full drug name
ZnSO₄	zinc sulfate	morphine sulfate	Use full drug name
µg	microgram	mg (milligram)	Use "mcg"
AD, AS, or AU	right ear, left ear, each ear	right eye, left eye, each eye	Spell out "right ear," "left ear," or "each ear"
BIW or biw	2 times a week	2 times a day	Spell out "2 times weekly"
cc	cubic centimeters	u (units)	Use "mL"
D/C	Discharge or discontinue	One mistaken for the other	Spell out "discharge" or "discontinue"
gr	grain(s)	gram	Use the metric system (e.g., mcg, g)
HS or hs	half strength or hours of sleep (at bedtime)	one mistaken for the other	Spell out "half strength" or use "HS" for at bedtime
IN	intranasal	IM or IV	Spell out "intranasal"
IT	intrathecal	Intratracheal, intratumor, intratympanic, inhalation therapy	Spell out "intrathecal"
IU¹	international units	IV or 10	Spell out "units"
l	liter	1 (one)	Use uppercase "L"
M or K	thousand	million	Spell out "thousand"
ml	milliliter	1 (one)	Use "mL" (with lowercase "m" and uppercase "L")
MM or M	million	thousand	Spell out "million"
Ng or ng	nanogram	mg (milligram) or nasogastric	Spell out "nanogram"
OD, OS, or OU	right eye, left eye, each eye	right ear, left ear, each ear	Spell out "right eye," "left eye," or "each eye"
o.d. or OD	once daily	right eye	Spell out "daily"
OJ	orange juice	OD (right eye), OS (left eye)	Spell out "orange juice"
oz	ounce(s)	zero or O2	Use the metric system (e.g., mL)
q.d., qd, Q.D., or QD¹	every day	qid (4 times per day)	Spell out "daily"
q1d	daily	qid (4 times per day)	Spell out "daily"
q6PM, etc.	every evening at 6 PM	every 6 hours	Spell out “daily at 6 PM” or “6 PM daily”
Qhs	nightly at bedtime	qhr (every hour)	Use “QHS” or “qhs”
q.o.d., qod, Q.O.D, or QOD¹	every other day	qid (4 times per day) or qd (daily)	Spell out "every other day"
SC, SQ, sq, or sub q	subcutaneously	SC mistaken as SL (sublingual); SQ mistaken as "5 every"; q in sub q mistaken as "every"	Use "SUBQ" or spell out "subcutaneously"
SSRI or SSI	sliding scale regular insulin, sliding scale insulin	selective serotonin reuptake inhibitor or strong solution of iodine (Lugol's)	Spell out "sliding scale insulin"
tbsp or Tbsp	tablespoon(s)	teaspoon(s)	Use the metric system (e.g., mL)
TIW or tiw	3 times a week	3 times a day or twice a week	Spell out "3 times weekly"
tsp	teaspoon(s)	tablespoon(s)	Use the metric system (e.g., mL)
u or U¹	units	0 (zero), 4 (four) or cc	Spell out "units"
UD	as directed (ut dictum)	unit dose	Spell out "use as directed"
/ (slash mark)	separates two doses	1 (one)	Spell out "and" between drug doses
+	plus or and	4 (four)	Spell out “plus,” “and," or “in addition to”
1/2 tablet	half tablet	1 or 2 tablets	Spell out “half tablet”; avoid using fractions or decimals
Doses expressed as Roman numerals (e.g., V)	5	designated letter (e.g., the letter “V”) or the wrong numeral (e.g., 10 instead of 5)	Use only Arabic numbers (e.g., 1, 2, 3) to express doses
Zero after a decimal point (e.g., 1.0 mg)¹	1 mg	10 mg	DO NOT USE zero after a decimal point for doses expressed as a whole number
No zero before a decimal point (e.g., .1 mg)¹	0.1 mg	1 mg	ALWAYS USE zero before a decimal point when the number is less than 1
Ratio expression of a concentration of a SINGLE-ENTITY injectable drug product (e.g., epinephrine 1:1,000; 1:10,000; 1:100,000) (note: combination local anesthestics are an exception [e.g., lidocaine 1% and epinephrine 1:100,000])	1:1,000 (contains 1 mg/mL); 1:10,000 (contains 0.1 mg/mL); 1:100,000 (contains 0.01 mg/mL)	wrong strength	Express the concentration in terms of quantity per total volume (e.g., 1 mg per 10 mL)
@	at	2 (two)	Spell out "at"
x1	administer once	administer for 1 day	Spell out “for 1 dose”
>	greater than	<	Spell out "greater than"
<	less than	4 or >	Spell out "less than"
&	and	2 (two)	Spell out "and"
°	hour	zero	Spell out "hr," "h," or "hour"
∅or ⦶	zero or null sign	4 (four), 6 (six), 8 (eight) or 9 (nine)	Use “0” or “zero” or describe intent using whole words
#	pound(s)	Number sign	Use the metric system (kg or g) rather than pounds or use “lb” if referring to “pounds”
Drug name and dose run together (e.g., propranolol20 mg; Tegretol300 mg)	propranolol 20 mg; Tegretol 300 mg	propranolol 120 mg or Tegretol 1300 mg	Place space between drug name, dose, and unit of measure
Numerical dose and unit of measure run together (e.g., 10mg; 10units)	10 mg; 10 units	m in “mg” and u in “units” mistaken for one or two zeroes	Place space between drug dose and unit of measure
Large doses without properly placed commas (e.g., 100000 units; 1000000 units)	100,000 units; 1,000,000 units	100000 mistaken as 10,000 or 1,000,000; 1,000,000 mistaken as 100,000	Use commas for drug doses at or above 1,000 or spell out (“100 thousand” or “1 million”)

¹Appears on The Joint Commission's "Do Not Use" list of abbreviations.

Modified from ISMP's List of Error-Prone Abbreviations, Symbols, and Dose Designations, 2024.

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