Pharmacy Abbreviations and Sig Codes for the PTCB Exam
Sig codes are the shorthand on a prescription that you turn into label directions. The 2026 PTCE content outline lists sig codes, abbreviations, medical terminology and symbols under Order Entry and Processing, and error-prone abbreviations under Patient Safety. Learn both lists: what the codes mean, and which ones you should never write.
Common sig codes
| Abbreviation | Meaning |
|---|---|
| a.c. | before meals |
| p.c. | after meals |
| b.i.d. | twice a day |
| t.i.d. | three times a day |
| q.i.d. | four times a day |
| q4h | every 4 hours |
| q24h | once a day |
| h.s. | at bedtime |
| p.o. (PO) | by mouth (per os) |
| p.r.n. (prn) | as needed |
| stat | immediately |
| IM | intramuscularly |
| IV | intravenously |
| SC (SQ) | subcutaneously |
| gtt(s) | drop(s) |
| tab(s) | tablet(s) |
| cap(s) | capsule(s) |
| susp | suspension |
| sol’n | solution |
| disp | dispense |
| Sig: | instructions to the patient |
| ut dict. | as directed |
| q.s. | a sufficient quantity |
| o.d. / o.s. / o.u. | right eye / left eye / both eyes |
| a.d. / a.s. / a.u. | right ear / left ear / both ears |
| tsp / Tbs | teaspoon / tablespoon |
Reading a sig: worked examples
- 1 tab po bid prn pain → Take 1 tablet by mouth twice a day as needed for pain.
- 2 caps po tid pc → Take 2 capsules by mouth three times a day after meals.
- 5 mL po t.i.d. a.c. → Take 5 mL by mouth three times a day before meals.
- 10 mL po q4h prn cough → Take 10 mL by mouth every 4 hours as needed for cough.
- 1 tab po h.s. → Take 1 tablet by mouth at bedtime.
Sig codes also drive days supply. For “2 caps po tid pc” with #60 dispensed, the patient takes 2 × 3 = 6 capsules a day, so 60 ÷ 6 = 10 days. See more in pharmacy math formulas.
Abbreviations you must not use
The Joint Commission requires accredited organizations to follow a list of prohibited abbreviations, symbols and dose designations. At a minimum it includes:
| Do not use | Write instead |
|---|---|
| U, u | unit |
| IU | international unit |
| Q.D., QD, q.d., qd | daily |
| Q.O.D., QOD, q.o.d., qod | every other day |
| Trailing zero (X.0 mg) | X mg |
| Lack of leading zero (.X mg) | 0.X mg |
| MS, MSO4 | morphine sulfate |
| MgSO4 | magnesium sulfate |
The list applies to all orders, preprinted forms and medication-related documentation, handwritten or electronic. A trailing zero is allowed only to show precision in values such as lab results, never in medication orders. The Institute for Safe Medication Practices (ISMP) publishes a longer list of error-prone abbreviations.
Tall Man lettering
Tall Man lettering uses capital letters to highlight the part of a drug name that differs from a look-alike name. Examples from FDA's list:
- glipiZIDE / glyBURIDE
- hydrALAZINE / hydrOXYzine
- buPROPion / busPIRone
- traZODone / traMADol
- predniSONE / prednisoLONE
- niCARdipine / NIFEdipine
Practice sig codes, days supply and dose calculations with free drills and a 20-question PTCB-style test.
Start free practice