What does PO BID mean on a prescription?
PO BID means take the medication by mouth twice daily. It is one of the most common sig codes you will see on a prescription, and it is made of two separate abbreviations.
What each part stands for
PO is short for the Latin per os, which means by mouth. It tells you the route: the medication is swallowed rather than applied to the skin, dropped in the eye, or inhaled.
BID is short for the Latin bis in die, which means twice a day. It tells you the frequency.
Put together, PO BID tells you the route and the frequency, but not the amount. That is why a complete sig almost always has a quantity in front of it.
How it looks on a real label
Here is how a few common PO BID sigs translate into the directions a patient reads:
| Sig code | Label directions |
|---|---|
1 tab po bid | Take 1 tablet by mouth twice daily |
2 tabs po bid pc | Take 2 tablets by mouth twice daily after meals |
1 cap po bid ac | Take 1 capsule by mouth twice daily before meals |
1 tab po bid hs | Take 1 tablet by mouth twice daily at bedtime |
BID is not the same as Q12H
This trips people up. BID means twice a day, which in practice usually means morning and evening, and the patient has some flexibility. Q12H means every 12 hours, on a strict schedule, including overnight if that is when the next dose falls.
For most medications the difference does not matter much. For antibiotics and some cardiac drugs it does, because keeping the blood level steady is the point. If a prescriber writes Q12H rather than BID, they usually mean it.
Codes you will see alongside PO BID
PO BID is often combined with a timing or condition code:
- AC (ante cibum) means before meals
- PC (post cibum) means after meals
- HS (hora somni) means at bedtime
- PRN (pro re nata) means as needed
Related frequency codes
| Sig code | Meaning |
|---|---|
PO QD | by mouth once daily |
PO TID | by mouth three times daily |
PO QID | by mouth four times daily |
PO Q8H | by mouth every 8 hours |
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This page is educational and is not medical advice. Always follow the directions on your own prescription and ask your pharmacist if anything is unclear.