The Most Common Medication Errors in the OR

Patient Safety in the Operating Room

Medications are vital for patients undergoing surgery, but they can also pose risks if not given correctly.

The medical literature is frighteningly sparse on medication errors in the operating room. Unless the effects of the error are devastatingly obvious, most of our knowledge of medication errors in the operating room consists of self-reported events.

What Are Medication Errors?

Medication errors are preventable events that may cause or lead to inappropriate medication use or patient harm. In most scenarios, they involve some form of human error.

Why Are Medication Errors Important?

Medication errors are having a moment in the public eye, and for a good reason. Medical errors are at least the third most common cause of death in the US. (1)

Despite unprecedented levels of safety in modern anesthesia, medication errors still occur and can be devastating for patients and their families.

Learning the most common medication errors and how to prevent them is vital to keeping our patients safer in the future.

Why do medication errors still occur?

Despite the dedication of well-meaning anesthesia providers, medication errors continue to occur. Environmental design plays a role in making specific errors more common than others in the operating room.

James Reason’s Swiss Cheese Model of Failure

A Common Cause Of Medication Errors

  • When you reach for a medication vial, what will you get?
  • Are lookalike medication vials a common occurrence when obtaining medications at your institution?
  • How do you KNOW you have the proper medication?
  • What can you do to minimize the risks to your patients?

Look-a-like medication vials are a prevalent problem for Anesthesiologists.

Given that, in many hospitals, most anesthesia syringes are prepared in the surgical suite by the anesthesia provider, the tasks associated with selecting the medications, preparing the syringes, and administering the medications by a single practitioner can be a source of significant iatrogenic patient harm (4)

The journal Anesthesiology published a prospective study in which the authors found that about one in 20 perioperative medication administrations and half of all surgical procedures resulted in a medication error or adverse drug event. All medication errors and 80% of the adverse drug events were deemed preventable.

More than one-third of the medication errors led to actual patient harm, and the remaining two-thirds had the potential to cause harm. (2)

There were two crucial timing points when medication errors occurred.

First, more than half of the errors occurred within the first 20 minutes of anesthesia induction.

Second, procedures longer than six hours or requiring 13 medications or more had higher error rates.

The most common medication errors in the OR are:

  • The failure to label a syringe followed by accidental administration of the wrong medication.
  • Incorrect labeling of a syringe
  • Misreading a label or administering a wrong drug due to a lookalike drug vial
  • Administering medication at the wrong time, such as an antibiotic to prevent surgical site infections.
  • Omitting doses
  • Inadvertent boluses of medications remaining in tubing flushed in with subsequent fluid administration.

Human Causes vs. System Causes of Medication Errors

The most common causes of perioperative medication errors can often be linked to human and system causes. The system causes of error are often overlooked and lead to human error.

Human causes of medication errors in the OR include:

  • Unlabeled syringes when medication labeling is regarded as desirable but not mandatory
  • Overreliance on the expected location of medications and syringes on the cart or tray
  • Overreliance on color-coded labels
  • Failure to carefully read labels
  • Repetitive task designs that foster automatic behavior with little conscious attention required (2)


If operating rooms have not been equipped with the means to avoid these common medication errors, patients have no choice but to rely solely on the anaesthesiologist’s mental focus and vigilance to perform medication administration correctly, each and every time.  

Of course, administering every medication correctly over the course of a 30-year career is impossible because human errors are inevitable and arguably normal. Therefore, medication errors that result from human error are also normal.

It is crucial that systems of safety be engineered to bypass human factors to prevent medication errors from ever occurring. If your organization hasn’t started this journey yet, the time to start is now.

References and Additional Reading:

  1. Makary MA, Daniel M. Medical error-the third leading cause of death in the US. BMJ. 2016 May 3;353:i2139. doi: 10.1136/bmj.i2139. PMID: 27143499.
  2. Nanji KC, Patel A, Shaikh S, et al. Evaluation of perioperative medication errors and adverse drug events. Anesthesiology. 2016;124(1):25–34.
  3. Eichhorn JH. APSF hosts a medication safety conference. Consensus group defines challenges and opportunities for improved practice. APSF Newsletter. 2010;25(1):1, 3–8
  4. Shaw, R. E., & Litman, R. S. (2014). Medication safety in the operating room: A survey of preparation methods and drug concentration consistencies in children’s hospitals in the United States. Joint Commission Journal on Quality and Patient Safety,
  5. Acheampong F, Anto BP, Koffuor GA. Medication safety strategies in hospitals—a systematic review. Int J Risk Saf Med. 2014;26(3):117-131.
  6. Institute of Medicine. Preventing Medication Errors. Aspden P, Wolcott J, Bootman JL, et al, eds. Washington, DC: National Academies Press; 2007.
  7. Reason J. Human error: models and management. BMJ. 2000 Mar 18;320(7237):768-70. doi: 10.1136/bmj.320.7237.768. PMID: 10720363; PMCID: PMC1117770.

Welcome to Patient Safety Experts. Dive into the intricacies of safe patient care and quality improvement through the lens of a CV anesthesiologist and patient safety specialist

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