What does AC mean on a prescription?
AC means before meals. A medicine prescribed AC is taken shortly before you eat, typically 30 to 60 minutes beforehand unless the label says otherwise.
- Means:
- before meals
- From:
- ante cibum
- Type:
- When
- Also written:
- ac, a.c., AC
What it means in practice
AC is Latin for ante cibum, “before food”. It is used when food would block absorption, or when the medicine needs to act on an empty stomach — some diabetes medicines, thyroid hormone and certain antibiotics. AC is normally combined with a frequency, as in TID AC.
Example on a prescription
Levothyroxine 50 mcg PO QD AC breakfast
Take one 50 mcg levothyroxine tablet by mouth once a day, before breakfast.
Commonly confused with
- PCPC is post cibum, after meals — the opposite instruction.
Worth knowing
Taking an AC medicine with food can substantially reduce how much is absorbed. If you forget and take it with a meal, ask your pharmacist whether to re-dose rather than guessing.
Frequently asked questions
How long before a meal is AC?
Usually 30 to 60 minutes, but it varies by medicine. Levothyroxine, for example, is often specified as 30 to 60 minutes before breakfast. Check the label.
What does TID AC mean?
Three times a day, each dose before a meal — so before breakfast, lunch and dinner.
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.