Do Not Use: Dangerous Abbreviations, Symbols, and Dose Designations
2025 Update
This bulletin describes the development of an updated list through a multi-input process that included an environmental scan, incident analyses, and stakeholder consultations from health care sectors and regions across Canada.
Do Not Use List
INTRODUCTION
When communicating medication information, the use of certain abbreviations, symbols, and dose designations has been identified as a significant contributing factor to serious and potentially fatal medication incidents. In 2006, ISMP Canada published a list of dangerous abbreviations, symbols, and dose designations to avoid;1 the list was reaffirmed in 2018.2 This bulletin describes the development of an updated list reflecting the evolution of communication in different care settings.
METHODOLOGY
To ensure the updated list remains relevant and effective in reducing medication incidents, key development steps were undertaken, as outlined in Figure 1.
FIGURE 1. Steps undertaken in the development of the 2025 update of the Do Not Use: Dangerous Abbreviations, Symbols, and Dose Designations.
The number of incidents in which errors could be attributed, at least in part, to the communication of medication information using French-specific abbreviations, symbols, or dose designations was insufficient to identify French-language items for the list.
HIGHLIGHTS
The following items have been included in the updated Do Not Use list:
- Fractional representations of frequency or duration (e.g., 2/52 to convey 2 weeks)
In the 2018 review of the Do Not Use list, fractions were described as having some association with harm or the potential for harm.2 Since that publication, reports of medication incidents involving errors of frequency or duration have identified the use of fractional representations as a key contributing factor. - Roman numerals (e.g., ii to convey 2)
In health care, Roman numerals may be mistaken for letters or other numbers, or may be misinterpreted as a route of administration (e.g., iv [representing 4] may be mistakenly interpreted as IV [representing intravenous]). - Latin abbreviations for aural (ear) route of administration (e.g., AS for left ear)
The abbreviations for the aural route of administration (i.e., AS, AD, and AU for left ear, right ear, and both ears, respectively) may be misinterpreted as indicating administration in the eye (i.e., OS, OD, OU, respectively), or they may be mistaken for each other, resulting in treatment of the wrong ear. Previous versions of the Do Not Use list already included Latin abbreviations for administration into the eye. - Use of the abbreviation “d” to express days or doses
The use of “d” could be interpreted to mean days or doses (e.g., the expression “for 7 d” could be interpreted as 7 doses, instead of the intended 7-day treatment), resulting in the incorrect duration of treatment.
INTENDED USE AND RECOMMENDATIONS
Given the range of health care settings and the diversity of populations served, it is recommended that individual organizations and pharmacies adopt the Do Not Use: Dangerous Abbreviations, Symbols, and Dose Designations or adapt it to reflect their local context. This approach aligns with accreditation standards.8
The Canadian list is applicable to all health care settings in which communication about medication information takes place.
RECOMMENDATION:
Individual health care organizations and pharmacies adopt the 2025 Do Not Use: Dangerous Abbreviations, Symbols, and Dose Designations or adapt the list to reflect their local context.
Specifically, health care organizations and pharmacies are encouraged to do the following:
- Adopt or adapt the Do Not Use list to assist in maintaining an organization-specific list of dangerous abbreviations, symbols, and dose designations.
- Continuously improve electronic and/or paper information systems to reduce or obviate the need to use abbreviations (e.g., computerized prescriber order entry [CPOE], paper order sets).
- Consider using technical functions within electronic information systems to flag the use of dangerous abbreviations, symbols, and dose designations, and to inform preventive or corrective action.
- Raise awareness of the Do Not Use list, emphasizing how various shortened forms can be misinterpreted, thereby causing errors, as well as the need to be as precise and complete as possible when communicating medication-related information. Communicate to staff the importance of reporting medication incidents potentially associated with dangerous abbreviations, symbols, and dose designations.
- Periodically review the Do Not Use list to identify any abbreviations, symbols, or dose designations that may warrant inclusion or removal to reflect medication incident analysis findings, changes in practice, upgrades to electronic information systems, and/or updates to formularies.
CONCLUSION
ISMP Canada updated the Do Not Use list through a multi-input process that included an environmental scan, incident analyses, and stakeholder consultations from health care sectors and regions across Canada. The list of dangerous abbreviations, symbols, and dose designations considers reported harm (actual or potential), and the frequency of use and/or misinterpretation when communicating medication-related information. Organizations and health care providers are encouraged to adopt or adapt this evidence-informed list to meet the needs of information users in their own care environments.
The Canadian Medication Incident Reporting and Prevention System (CMIRPS) is a collaborative pan-Canadian program of Health Canada, the Canadian Institute for Health Information (CIHI), the Institute for Safe Medication Practices Canada (ISMP Canada) and Healthcare Excellence Canada (HEC). The goal of CMIRPS is to reduce and prevent harmful medication incidents in Canada.
Funding support provided by Health Canada. The views expressed herein do not necessarily represent the views of Health Canada.
The Healthcare Insurance Reciprocal of Canada (HIROC) provides support for the bulletin and is a member owned expert provider of professional and general liability coverage and risk management support.
The Institute for Safe Medication Practices Canada (ISMP Canada) is an independent national not-for-profit organization committed to the advancement of medication safety in all healthcare settings. ISMP Canada’s mandate includes analyzing medication incidents, making recommendations for the prevention of harmful medication incidents, and facilitating quality improvement initiatives.
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