Sig Codes and Prescription Abbreviations: PTCB Quick Guide
Master common prescription abbreviations and sig codes every pharmacy technician must know. From QD to PRN, this guide covers what the PTCE will test you on.
Understanding Sig Codes
The "sig" (signa) on a prescription tells the patient how to take the medication. These directions are written using Latin abbreviations that pharmacy technicians must translate into plain English for prescription labels. Knowing sig codes is fundamental to prescription processing and a tested skill on the PTCE.
Frequency Abbreviations
- QD - Once daily (quaque die)
- BID - Twice daily (bis in die)
- TID - Three times daily (ter in die)
- QID - Four times daily (quater in die)
- Q4H, Q6H, Q8H - Every 4, 6, or 8 hours
- QHS - At bedtime (quaque hora somni)
- PRN - As needed (pro re nata)
- QOD - Every other day (on the ISMP error-prone list)
Route Abbreviations
- PO - By mouth (per os)
- SL - Sublingual (under the tongue)
- TOP - Topically
- INH - Inhalation
- IM - Intramuscular
- IV - Intravenous
- SC or SubQ - Subcutaneous
- PR - Rectally (per rectum)
- OU, OD, OS - Both eyes, right eye, left eye
- AU, AD, AS - Both ears, right ear, left ear
Other Common Abbreviations
- AC - Before meals (ante cibum)
- PC - After meals (post cibum)
- UD - As directed (ut dictum)
- NR - No refills
- DAW - Dispense as written
- NKA - No known allergies
Error-Prone Abbreviations
ISMP maintains a list of abbreviations that should not be used because they lead to errors. These include QD (mistaken for QID), U (mistaken for 0 or 4), IU (mistaken for IV), and trailing zeros (1.0 mistaken for 10). The PTCE may test your knowledge of which abbreviations are on the error-prone list.
Quiz yourself on sig codes with PTCB flashcards until translating prescriptions becomes automatic.
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