BID means twice a day, TID three times a day and QID four times a day. Type the directions
the way they are written, such as “1 tab PO TID”, and this reads them back in
plain words: 1 tablet by mouth three times a day, at 08:00, 15:00 and 22:00 if you are up
from 8am to 10pm. It also warns you when the directions use an abbreviation that safety
lists say to avoid, such as QD or a trailing zero.
Doz is a free download on the App Store:
type the plain-English version into it, such as “1 tablet three times a day”,
and it builds the reminder schedule on your iPhone (English only). It is free for up to four
medications, with no account.
What the common abbreviations mean, with times
The times below are what the translator gives with a first dose at 08:00 and bedtime at
22:00. Change those two times above and the dose times move with them. For the Latin behind
each one and the full list, see
QID meaning and other prescription
abbreviations.
| On the label | Means | Dose times (up 08:00 to 22:00) |
|---|
| QD, daily | once a day | 08:00 |
| BID, BD | twice a day | 08:00, 20:00 |
| TID, TDS | three times a day | 08:00, 15:00, 22:00 |
| QID, QDS | four times a day | 08:00, 12:40, 17:20, 22:00 |
| QAM | every morning | 08:00 |
| QHS, HS | at bedtime | 22:00 |
| QOD | every other day | 08:00, every other day |
| q12h | every 12 hours | 08:00, 20:00 |
| q8h | every 8 hours | 08:00, 16:00, 00:00 |
| q6h | every 6 hours | 08:00, 14:00, 20:00, 02:00 |
| QPM | every evening | One evening time you choose |
| PRN | as needed | No fixed times |
It also reads routes (PO by mouth, SL under the tongue, SUBQ under the skin, IM, IV, PR,
OD, OS and OU for the eyes, AD, AS and AU for the ears), meals (AC before, PC after),
amounts (tab, cap, gtt, tsp), lengths such as x7d (for 7 days) and limits such as
max 8/24h (at most 8 in 24 hours).
How the times are worked out
BID, TID and QID say how many doses, not when. If a strict round-the-clock gap (12, 8 or
6 hours) from your first dose ends by bedtime, you get that. If it would run past bedtime,
the doses are spread evenly between your first dose and bedtime instead, which is why TID
comes out 7 hours apart for someone up from 08:00 to 22:00. The
times-a-day schedule works the same way.
q6h, q8h and the other q-hour abbreviations are a strict interval, night included. The
translator starts them at your first dose, lists every dose in the first 24 hours and
tells you which ones fall while you would usually be asleep. When the gap does not divide
into 24 hours, as with q5h or q7h, it also says how much later the times start the next
day. More on that difference in
every 8 hours vs three times a day.
PRN, ranges such as q4-6h, and STAT get no times, because they have no fixed schedule. For
an as-needed medicine, the next dose time
calculator works out when you can take the next one.
Abbreviations it warns about
Some abbreviations have caused medication errors often enough that safety bodies tell
prescribers not to use them. The translator still reads them, and adds a warning:
| On the label | What has gone wrong | Listed by |
|---|
| QD, QOD | QD read as QID (four times a day); QOD read as QD or QID | The Joint Commission (Do Not Use) and ISMP |
| U, IU | U read as 0 or 4; IU read as IV or 10 | The Joint Commission (Do Not Use) and ISMP |
| 1.0 mg, .5 mg | The decimal point is missed: read as 10 mg or 5 mg | The Joint Commission (Do Not Use) and ISMP |
| MS, MSO4, MgSO4 | Morphine sulfate and magnesium sulfate confused | The Joint Commission (Do Not Use) and ISMP |
| OD (once daily) | Read as right eye, so oral liquid was put in the eye | ISMP |
| OD, OS, OU and AD, AS, AU | Eye and ear abbreviations confused with each other | ISMP |
| SC, SQ, sub q | SC read as SL (under the tongue); SQ read as “5 every” | ISMP |
| q1d, qn, TIW, BIW, UD, q6PM | Misread as a different frequency, or UD as “unit dose” | ISMP |
Anything it does not recognise is listed as “not recognised”. Ask your
pharmacist about those before you take a dose.
Sources
Common questions
What does BID mean on a prescription?
BID means twice a day, from the Latin bis in die. With a first dose at 08:00 and bedtime at 22:00, that is 08:00 and 20:00, 12 hours apart. In the UK it is written BD.
What times are TID and QID?
TID is three times a day and QID four times a day. Between 08:00 and 22:00, TID gives 08:00, 15:00 and 22:00, and QID gives 08:00, 12:40, 17:20 and 22:00. A strict every 8 or every 6 hours would put a dose in the night, which is why a label that needs a strict gap says q8h or q6h instead.
Is QID the same as q6h?
No. QID means four doses a day, usually spread across your waking hours. q6h means every 6 hours around the clock: from 08:00 that is 08:00, 14:00, 20:00 and 02:00. If your label says q6h, keep to the interval.
Why does it warn about QD?
QD, once a day, is on The Joint Commission’s Do Not Use list, and ISMP notes it being misread as QID, four times a day. That would turn one dose into four. ISMP recommends writing daily instead.
Can I type my prescription into Doz?
Doz reads plain English, not abbreviations. Type the plain version this page gives, such as 1 tablet twice a day, and Doz builds the reminder schedule on your iPhone. It is free for up to four medications.
One thing this cannot do
This is an arithmetic tool, not medical advice. It works out numbers from what you type
in — it does not know your medication, your prescription, or what you should do
if something goes wrong. Anything about changing a dose, spacing doses differently, or
handling a missed dose is a question for your doctor or pharmacist.