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 (USP) 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 (NCC-MERP) 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 professional, 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" but select dopamine instead of dobutamine. Working amidst 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 (TJC) monitors the use of frequently prescribed high-alert medications, which include insulin, opioids, injectable potassium chloride (or phosphate) concentrate, intravenous anticoagulants (such as heparin), 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 (ex.: 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, ten-fold 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 non-pharmacists 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 his or her medication regimen and can question the health care professional. 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 professional, 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. 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.
• 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 ml 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.

• Billstein-Leber M, Carrillo C, Cassano AT, et al. ASHP guidelines on preventing medication errors in hospitals. Am J Health Syst Pharm. 2018;75: 1493–517.
• Wang H, Tao D, Yan M. Effects of text enhancement on reduction of look-alike drug name confusion: A systematic review and meta-analysis. Qual Manag Health Care 2021;30:233–43.
• ISMP. Targeted Medication Safety Best Practices for Hospitals ISMP Guidelines.February 9, 2022.https://www.ismp.org/guidelines/best-practices-hospitals
• Koeck JA, Young NJ, Kontny U, et al. Interventions to reduce medication dispensing, administration, and monitoring errors in pediatric professional healthcare settings: A systematic review. Front Pediatr. 2021;9:633064.
• Kohn LT, Corrigan JM, Donaldson MS (eds). To Err Is Human: Building a Safer Health System. National Academy Press, Washington, DC (1999).
• Manias E, Snezana K, Wu A. Interventions to reduce medication errors in adult medical and surgical settings: a systematic review. Ther Adv Drug Saf. 2020;11:2042098620968309. http://dx.doi.org/10.1177/2042098620968309
• National Coordinating Council for Medication Error Reporting and Prevention. (2023). About Medication Errors: What is a Medication Error? http://www.nccmerp.org/about-medication-errors
• Strudwick G. Factors associated with barcode medication administration technology that contribute to patient safety: An integrative review. J Nurs Care Qual. 2018;33:79–85.