QID (four times a day)
QID means four times a day. It is short for the Latin quater in die, and is also written q.i.d.; British charts and labels use QDS.
Easily confused with
How to read it
The American Heritage Dictionary and the Minnesota Board of Pharmacy give the Latin as quater in die, and MedlinePlus lists QID as “four times a day”, an abbreviation a doctor may write on a prescription. The Minnesota list gives the British form, q.d.s., as quater die sumendus, and the Lincolnshire Partnership NHS Foundation Trust’s jargon list has QDS. QID follows BID and TID in the same series.
Also searched as: q.i.d., qid meaning, qid medical abbreviation, quater in die.
These pages explain what medical abbreviations and symbols stand for. They are not medical advice and give no doses: a pharmacist or prescriber can explain what any label means for you.
Why QID gets mixed up with QD
The commonest confusion runs the other way: QD, “every day”, read as QID. ISMP’s list of error-prone abbreviations says QD is mistaken as q.i.d. “especially if the period after the q or the tail of a handwritten q is misunderstood as the letter i”, and lists q1d (daily) and QOD (every other day) as mistaken for qid too. The Pennsylvania Patient Safety Authority reported in 2005 an order written as QD that was read as QID.
What q.i.d. leaves out
Joel Weaver, editor of Anesthesia Progress, gave two objections to q.i.d. in a 2006 editorial. It says how many times, not how the times are spaced: all four could fall before noon and still be q.i.d. And in poor handwriting it can be misread as q.4 h. (quaque quarta hora, every four hours), which comes to six times a day.
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Sources
- q.i.d. (American Heritage Dictionary entry), The American Heritage Dictionary of the English Language, Fifth Edition, HarperCollins Publishers, q.i.d., abbr.
- Appendix B: Some Common Abbreviations, MedlinePlus, U.S. National Library of Medicine, QID
- Partial list of prescription abbreviations, Minnesota Board of Pharmacy, Partial list of prescription abbreviations, Minnesota Board of Pharmacy, q.i.d.; q.d.s.
- ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations (2024), 2024 edition, Institute for Safe Medication Practices, Abbreviations for Frequency/Instructions for Use: QD, QOD, q1d
- It’s time to throw out old-fashioned Latin abbreviations, Joel M. Weaver, Anesthesia Progress 2006;53(1):1–2, American Dental Society of Anesthesiology, Paragraph 4
- Abbreviations: A Shortcut to Medication Errors, Pennsylvania Patient Safety Advisory, 2005 Mar;2(1):19–21, Pennsylvania Patient Safety Authority, Paragraph on frequency abbreviations
- Meaning of abbreviations and jargon, Lincolnshire Partnership NHS Foundation Trust, carers’ support pages, Lincolnshire Partnership NHS Foundation Trust, Abbreviations, Q
Last reviewed September 30, 2026 by Rory Hansen. How we research