Prescription abbreviations
What OD means
on a prescription.
OD on a prescription means once a day. It is short for the Latin omni die, “every day”, and is used on prescriptions in India and the UK. On an eye prescription the same letters can mean the right eye, so if drops are marked OD, ask the pharmacist which is meant.
OD
once a day
omni die, Latin for “every day”
- Also: right eye, on an eye prescription, from oculus dexter
Also written o.d., QD (US)
Once a day, or the right eye?
Both meanings are in use. Indian and UK references give OD as once a day, while an American consumer guide from the safety group ISMP gives it as the right eye, from oculus dexter. Because the two get mistaken for each other, ISMP advises writing “daily” instead of OD, and “right eye” on eye prescriptions.
QD, the American form
American prescriptions sometimes write once a day as QD, from quaque die. ISMP lists QD as error-prone because it has been misread as QID, four times a day, and marks it as one of The Joint Commission’s “do not use” abbreviations.
What OD doesn’t say
It says how often, not how much or exactly when. The amount, the time of day and anything about food come from the rest of the prescription, the label or the pharmacist.
Setting it up in AlongWell
Type the medicine as the prescription has it, such as “Metformin 500 OD”, and AlongWell reads OD as once a day. You check the time of day before saving, and can change anything.
Questions
What does OD mean on a prescription?
Once a day. OD stands for the Latin omni die, “every day”. On an eye prescription the same letters can mean the right eye instead.
Is OD the same as QD?
Both mean once a day. OD is used in India and the UK. QD is an American form that safety groups advise against, because it can be misread as QID, four times a day.
What time should I take a medicine marked OD?
OD only says how often. Follow any time the prescription gives, or ask your doctor or pharmacist when to take it.
Sources
- Shetty Y and others, Indian Journal of Medical Research, 2024, read 28 October 2026
- College of Optometrists (UK): pharmacy and drug terms, read 28 October 2026
- ISMP Consumer Medication Safety: Learn to read a prescription, read 28 October 2026
- ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations (2024), read 28 October 2026
- ISMP Canada: Do Not Use: Dangerous Abbreviations, Symbols and Dose Designations, read 28 October 2026
This page explains what an abbreviation means. It doesn’t say how much to take or when: follow what the doctor wrote, and ask your pharmacist if any part of a prescription is unclear.
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