What does SIG mean on a prescription?
SIG is the part of a prescription that holds the patient instructions. From the Latin signa, “write”, it tells the pharmacist what to print on the label.
- Means:
- write / label the instructions
- From:
- signa
- Type:
- Pharmacy instruction
- Also written:
- sig, Sig., SIG
What it means in practice
On a written prescription the SIG line is where the dose, route, frequency and any conditions go — so “Sig: 1 tab PO BID PC” becomes “take one tablet by mouth twice a day after meals” on the bottle. When people talk about decoding sig codes, they mean the abbreviations that live on this line.
Example on a prescription
Sig: 1 tab PO BID PC
Label it: take one tablet by mouth twice a day, after meals.
Commonly confused with
- DISPDisp is how much to dispense — the quantity. Sig is how to take it.
- RXRx heads the prescription itself; Sig is the instruction line within it.
Frequently asked questions
What does SIG mean on a prescription?
It introduces the directions for the patient — the dose, route and frequency the pharmacist prints on the label.
What is a sig code?
An abbreviation used on the Sig line, such as PO, BID, TID, PRN or AC. Together they compress the instructions into a few characters.
Related abbreviations
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This page explains prescription notation for general information. It is not medical advice and does not replace your prescriber or pharmacist. If a label is unclear or differs from what you were told, check with your pharmacy before taking the medicine.