What does “Medication error” mean?
Short answer
A medication error is a preventable event that may lead to wrong medication use or harm (NCC MERP). CMS adds its own wording for nursing homes.
Also known as: med error, drug error
How groups define it
| Group | Definition |
|---|---|
| NCC MERP | A preventable event that may lead to wrong medication use or patient harm while the drug is under the control of a clinician, patient or consumer |
| CMS (Appendix PP, F760) | Preparing or giving medication in a way that does not follow the prescriber's order, the maker's specifications (not suggestions), or accepted professional standards |
| AHRQ PSNet | A mistake of doing or not doing, at any step from prescribing until the patient gets the drug |
CMS adds 'significant': an error that causes discomfort or puts health and safety at risk. F760 requires that residents be free of significant errors.
F759 covers the error rate: errors seen, divided by chances for error (doses given plus doses ordered but not given), times 100. A rate of 5 percent or more is cited, with no rounding up from 4.6.
Error and drug event
An adverse drug event is harm from taking a medication. It does not by itself mean an error. A preventable one comes from an error that reaches the patient and causes harm.
A potential one is an error that causes no harm, caught or by chance. The NCC MERP index sorts errors by result, from category A to I.
Example from CMS: a laxative left out for one day may cause little discomfort. If constipation lasts over three days, the error may be significant. A wrong-strength dose caught by a scan never reached the patient, so it is a near miss.
Mix-up: a medication error is not always harmful, and a harmful reaction is not always an error. Rate the result with a harm scale.
Frequently asked questions
What is a significant medication error?
In CMS nursing home guidance, an error that causes discomfort or puts health and safety at risk. It depends on the resident, drug type and dose. It is cited at F760.
How does CMS calculate a medication error rate?
Errors seen divided by chances for error (doses given plus doses ordered but not given), times 100. A rate of 5 percent or more is cited at F759, with no rounding up.
Is a missed dose a medication error?
It can be. CMS's own example is a laxative left out for a day. Whether it is significant depends on the resident and the drug.
Sources
- NCC MERP: About medication errors
- CMS State Operations Manual, Appendix PP: Guidance to Surveyors for Long Term Care Facilities
- AHRQ PSNet: Medication errors and adverse drug events (primer)
- NCC MERP: Index for categorizing medication errors
- HHS OIG: Adverse Events in Hospitals: National Incidence Among Medicare Beneficiaries (OEI-06-09-00090, November 2010)
Reviewed against the sources above on Oct 5, 2026. Rules change: confirm current requirements with the issuing body or your counsel before relying on any summary.
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