Glossary
QD
QD means once a day, from the Latin quaque die. It is on the Joint Commission's Do-Not-Use List because QD and QID are misread for each other, so the order is written out as "daily".
QD abbreviates once a day, from the Latin quaque die ("every day"). The safe form of the order is 1 tab PO daily.
QD sits on the Joint Commission's Official "Do Not Use" List for a reason a technician meets weekly: written by hand, QD and QID are one stroke apart — the i — and a once-daily drug taken four times a day is a fourfold overdose. The list's instruction is to write daily, so an order that arrives as QD is expanded to daily on the label. The same list bans QOD (every other day) in favor of the written phrase.
Read the whole family from the same root. QD is once a day, BID twice, TID three times, QID four; QAM and QPM pin a dose to morning and evening; QHS puts it at bedtime. None of those is a fixed clock — Q24H is the one that means an exact 24-hour interval, which is why it is used for the drugs whose interval matters and QD is not.
On the exam, QD appears as a translation (state the frequency) and inside a schedule question, where the frequency is what turns a dispensed quantity into a days supply.
Taught in
Related terms
- QID — QID means four times a day, from the Latin quater in die. It is the abbreviation most often misread as QD, and one tablet four times a day is the classic fourfold-overdose signature.
- BID — BID means twice a day, from the Latin bis in die. It is two doses in a day rather than a strict every-12-hours schedule — the fixed-interval order is written Q12H.
- QHS — QHS means at bedtime, from the Latin hora somni — the hour of sleep. ISMP lists it as error-prone because HS also reads as "half strength", so the words are written out instead.
Source: PTCB — PTCE Content Outline, effective January 6, 2026 (Domain 4 / KA 4.1, "Interpret prescription and medication orders … sig codes, abbreviations, medical terminology and symbols, and days supply", quoted verbatim); The Joint Commission, Official "Do Not Use" List (NPSG.03.05.01 — the minimum list an accredited organization must adopt, read in full); ISMP, List of Error-Prone Abbreviations, Symbols, and Dose Designations (the labels, symbols and abbreviations ISMP asks prescribers to write out) (outline accessed 2026-10-03, verbatim; the Joint Commission and ISMP lists read from their own fact-sheet and recommendation pages 2026-10-06 — each is revised on its own schedule; the definitions here restate this course's own order-interpretation-and-sig guide, which is the page whose sources back every definition above)