Use error

A use error is not the same as user fault; it often points to a design that invites mistakes. Under the MDR, use errors due to ergonomic features count as incidents for vigilance.

user action or lack of user action while using the medical device (3.10) that leads to a different result than that intended by the manufacturer (3.9) or expected by the user Note 1 to entry: Use error includes the inability of the user to complete a task. Note 2 to entry: Use errors can result from a mismatch between the characteristics of the user, user interface, task, or use environment. Note 3 to entry: Users might be aware or unaware that a use error has occurred. Note 4 to entry: An unexpected physiological response of the patient is not by itself considered use error. Note 5 to entry: A malfunction of a medical device that causes an unexpected result is not considered a use error. [SOURCE: IEC 62366-1:2015, 3.21, modified — Note 6 to entry deleted.]

ISO 14971:2019, clause 3.30

USER action or lack of USER action while using the MEDICAL DEVICE that leads to a different result than that intended by the MANUFACTURER or expected by the USER Note 1 to entry: USE ERROR includes the inability of the USER to complete a TASK. Note 2 to entry: USE ERRORS can result from a mismatch between the characteristics of the USER, USER INTERFACE, TASK, or USE ENVIRONMENT. Note 3 to entry: USERS might be aware or unaware that a USE ERROR has occurred. Note 4 to entry: An unexpected physiological response of the PATIENT is not by itself considered USE ERROR. Note 5 to entry: A malfunction of a MEDICAL DEVICE that causes an unexpected result is not considered a USE ERROR. Note 6 to entry: Figure 1 shows the relationships of the types of use.

IEC 62366-1:2015+AMD1:2020, clause 3.21

user action or lack of user action while using the medical device (3.34) that leads to a different result than that intended by the manufacturer or expected by the user Note 1 to entry: Use error includes the inability of the user to complete a task. Note 2 to entry: Use errors can result from a mismatch between the characteristics of the user, user interface, task or use environment. Note 3 to entry: Users might be aware or unaware that a use error has occurred. Note 4 to entry: An unexpected physiological response of the patient is not by itself considered a use error. Note 5 to entry: A malfunction of a medical device that causes an unexpected result is not considered a use error. [SOURCE: ISO 14971:2019, 3.30]

ISO 14155:2020, clause 3.52

A ‘use error’ is when the user’s action, or lack thereof, while using the device, leads to a different result or outcome than that expected by the user or intended by the manufacturer.

MDCG 2023-3 Rev.2, Question 5

User action or lack of action that was different from that expected by the manufacturer and caused a result that (1) was different from the result expected by the user and (2) was not caused solely by device failure and (3) did or could result in harm.

FDA guidance: Applying Human Factors and Usability Engineering to Medical Devices (August 2026), Section 3, Definitions

MDCG 2023-3 defines use error broadly as any user action or lack of action leading to a result different from what the user expected or the manufacturer intended. The FDA human factors guidance adds conditions: the result must not be caused solely by device failure and must have caused or could cause harm.