The TIW medical abbreviation means three times a week, so a treatment marked TIW is given on three separate days in each seven day week. It is common for dialysis sessions, some injections and certain therapy schedules.
TIW is also known for causing errors. Read quickly, it looks a lot like TID, three times a day, which would mean seven times as many doses. ISMP, a group that tracks medication errors, flags it as error-prone for that reason, and the safer form is to write 3 times weekly.
At a glance
Stands for
Three times a weekWritten as
TIW, tiw, t.i.w.Safer to write
3 times weekly, with the days namedWhere you see it
Dialysis orders, injection schedules, therapy plansRelated form
BIW for twice a week, also error-proneDo not confuse with
TID (three times a day)
What the TIW medical abbreviation means
TIW tells the reader how many days per week a treatment happens, not how many times per day. Three times a week usually means three nonconsecutive days with rest days between them, such as Monday, Wednesday and Friday, or Tuesday, Thursday and Saturday. The exact days are set by the clinic or the prescriber.
Unlike BID or TID, TIW does not come from a Latin phrase. It is plain English shorthand: T for three, I for times, W for week.
Where three times a week schedules appear
Some treatments work well on a weekly rhythm rather than a daily one. Common examples include:
- Hemodialysis: most people on in center dialysis go three times a week, often written HD TIW.
- Some injectable medicines: certain treatments given at a clinic or at home follow a three times weekly plan.
- Directly observed therapy: some infection treatment plans are given under observation on set days.
- Rehab: physical or occupational therapy orders often read 3x/week.
Dialysis unit note: "HD TIW MWF via L arm AVF, tolerated session well." The patient has dialysis on Monday, Wednesday and Friday through a fistula in the left arm. It shows the format only.
Why tiw gets flagged as error-prone
ISMP warns that TIW has been mistaken for three times a day and even for twice a week. A dose meant for three days a week given three times every day would be a serious overdose, while reading it as twice a week would mean missed treatment.
The safer written forms are 3 times weekly or three times a week, ideally with the days spelled out. Many electronic systems already print the days on the schedule. The related abbreviation BIW, twice a week, carries a similar risk of being read as twice a day, so the same advice applies: write 2 times weekly.
TIW compared with similar frequency terms
| Term | Meaning | Doses in a week |
|---|---|---|
| TIW | Three times a week | 3 |
| BIW | Twice a week | 2 |
| TID | Three times a day | 21 |
| QOD | Every other day (do-not-use form) | 3 or 4 |
| Weekly | Once a week | 1 |
Every other day and three times a week sound alike, but they drift apart over time. Every other day can land on a weekend; a TIW schedule usually keeps the same three weekdays.
Checking a three times weekly order
If you see TIW on a paper, ask a few quick questions to be sure it is understood the same way by everyone:
- Which three days of the week is the treatment given?
- What happens if a session or dose falls on a holiday or is missed?
- Does the pharmacy label say three times weekly, not three times daily?
Pharmacists and nurses welcome these checks. A simple calendar with the treatment days marked is one of the easiest ways to keep a weekly schedule on track at home.
TIW pharmacy abbreviation in training
Pharmacy technician and nursing students need to spot TIW on sight and rewrite it in the clearer wording. When entering an order, technicians type out the days and the weekly frequency. In documentation, nurses chart each treatment on the scheduled day. Weekly and daily timing terms are compared on the prescription abbreviations hub.
Weekly schedules differ from clinic to clinic. If a weekly treatment schedule on your own paperwork is unclear, the clinic, pharmacist or prescriber who wrote it can confirm the days.
Frequently asked questions
What does TIW mean on a prescription?
TIW means three times a week. Because it can be misread as three times a day, safer prescriptions write 3 times weekly and name the days.
What is the medical abbreviation for three times a week?
The traditional abbreviation is TIW, sometimes written tiw or t.i.w. Safety guidance recommends writing three times weekly in full instead.
Is TIW the same as TID?
No. TIW is three times a week and TID is three times a day. Confusing them could mean seven times too much or too little of a treatment.
Is TIW the same as every other day?
Not quite. Every other day falls on alternating days and can include weekends, while TIW usually means three fixed days each week, such as Monday, Wednesday and Friday.