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Published on 1 June 2002

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Recognising and avoiding medication errors

Christine Clark
BSc MSc FRPharmS
Medical Writer

The concept of drug safety is changing. It is now recognised that two types of adverse drug event (ADE) occur – namely adverse drug reactions (ADRs) and medication errors. Medication errors are, by definition, preventable, whereas ADRs are not. Therefore, in order to assure drug safety, both safe products and safe systems are needed.

Medication errors are an international phenomenon. A landmark report in the USA in 1999 estimated that medication errors kill 7,000 Americans each year.(1) One of every 131 deaths was the result of a medication error, and 2% of hospital patients experienced an ADE. Each one increased the cost of care by US$4,700 (e. 5,139).

Studies suggest that medication errors probably have a similar economic and clinical impact in Europe (see Table 1).


A comprehensive definition of a medication error was developed by the National Coordinating Council for Medication Error Reporting and Prevention (NCCMERP) in 1998. This defines a medication error as: “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; orders communication; product labelling; packaging and nomenclature; compounding; dispensing; administration; education; monitoring and use.”

Most errors have little potential for harm, such as confusion between the names Prozac and Proscar; however, a few are serious (see Figure 1). One important category is the “potential adverse events” or near-misses. These help to identify where a system is working and where it might fail. Preventable ADEs are those described as medication errors, while ADRs are those events that occur despite correct use of medicines and are not preventable. A study covering the period 1995–1999 identified 10,070 ADEs, of which 530 were medication errors, equivalent to 1.4 errors per admission.(6) This included five preventable ADEs and 35 potential ADEs. Another study found that 56% of errors originated in the prescription and 34% in drug administration. The remaining 10% arose during transcription and dispensing.(7)


“Error prevention” approach
A key step in error prevention is to assume that errors can occur and to redesign systems to make them resistant to failures. It is essential to recognise that errors are due to system failures and not professional incompetence. The multifactorial nature of many errors means that there are multiple possibilities for error prevention – a system that has checks and balances at many points is more likely to avert errors. The final step in error prevention is acknowledging the need to learn from mistakes. The creation of a “learning culture” in which there is open dialogue, and a nonpunitive reporting environment, is critical. Ideally, there should be both internal and national reporting systems.

System failures
The death of a newborn baby as a result of a medication error, in Denver, USA, in 1997, drew public attention to the issue of medication errors and illustrated the importance of a systems approach. The baby died as a result of the administration of intravenous (IV) benzathine penicillin. Unusually, criminal (instead of civil) charges were brought against the nurses involved. Michael Cohen (President, Institute of Safe Medication Practices: ISMP) volunteered to be an expert witness. Staff at the ISMP analysed the error “piece by piece” and found more than 50 system failures (see Table 2). All these errors “lined up” and allowed the overdose to be dispensed and administered.


The key to tackling medication errors is to look at what went wrong rather than who went wrong. Retraining one person helps the individual but it does not help to correct the system. Mandatory reporting is not the answer either, as it does not increase the number of reports as long as there is still punitive action. People need to feel confident about reporting errors and should be thanked for doing so. This will increase error reporting.

It is important to consider all elements of the medication-use system, including drug information; communication dynamics; labelling and packaging; storage; administration devices; environmental factors; and staff competence and training.

It is also important to understand the opportunities for error. For example, an error recently occurred in a unit dealing with laser eye surgery. It turned out that the only light on in the room had been the laser, and as a result, it was difficult for staff to read labels, and the wrong product had been selected.

Failure mode and effectiveness analysis (FMEA)
FMEA is a process for analysing the potential for errors. The first step is to draw a process flow diagram. The next step is to identify the potential errors (failure modes) in the processes and ask the question, “How bad can it be?”. Strategies for change can then be implemented. Consider the whole process – even look at delivery of the product. For example, confusion between intravenous and epidural doses has occurred when they have arrived at the ward at the same time. Another useful tip is to conduct an FMEA when a new product is introduced to assess the likely risks. “How safe will it be when it gets into the system?” is the question to ask.

Table 3 lists the common errors to be avoided.


Measures that help

  • The drug knowledge systems must be kept up to date. This is not always easy, and sometimes there is conflicting information.
  • When medication errors occur they should be ­discussed. New staff need to be aware of errors that have occurred, otherwise there is a risk that they will occur again.
  • Computer systems should be enhanced with warning systems, particularly linked to the medication administration system.
  • Give patients as much information as possible; for example, patients could be involved in check ­systems, but then staff must also listen if the patients identify discrepancies.

“High-alert” medications
One approach to safe systems is to identify drugs or drug groups where misuse is associated with a high risk of injury. Such a list might typically include: cancer chemotherapy, opiates, intravenous potassium, dopamine, intravenous digoxin, heparin and insulin.

Measures to reduce errors with high-alert medicines include: redundancies (building in an extra, critical step, such as a double check); forcing functions (making IV and enteral ­administration tubing incompatible); use of failsafe measures; externalising or centralising error-prone processes; use of auxiliary labels; standardising order communication; limiting drug access; limiting drug use; standardising protocols; and storage.


  1. Institute of Medicine. To err is human: building a safer health system (Medical Errors). Washington: IOM; 1999.
  2. Hallas J, Gram LF, Grodum E, et al. Drug related admissions to medical wards: a population based survey. Br J Clin Pharmacol 1992;33(1):61-8.
  3. Lagnaoui R, Moore N, Fach J. Adverse drug reactions in a department of systemic diseases-oriented internal medicine: prevalence, incidence, direct costs and avoidability. Eur J Clin Pharmacol 2000;56(2):181-6.
  4. Neale G, Woloshynowych M, Vincent C. Exploring the causes of adverse events in NHS hospital practice. J R Soc Med 2001;94(7):322-30.
  5. Raschetti R, Morgutti M, Menniti-Ippolito F, et al. Suspected adverse drug events requiring emergency department visits or hospital admissions. Eur J Clin Pharmacol 1999;54(12):959-63.
  6. Bates DW, Gawande AA. Error in medicine: what have we learned? Minn Med 2000;83(7):18-23.
  7. Bates DW, et al. Incidence of adverse drug events and potential adverse drug events. Implications for prevention. ADE Prevention Study Group. JAMA 1995;274:29-34.


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