BID (twice a day)
BID means twice a day. It is short for the Latin bis in die, and is also written b.i.d.; British charts and labels use BD.
How to read it
The American Heritage Dictionary and the Minnesota Board of Pharmacy both give the Latin as bis in die, and MedlinePlus lists BID as “twice a day”, an abbreviation a doctor may write on a prescription. The Minnesota list also gives b.d. as another form, and the Lincolnshire Partnership NHS Foundation Trust’s jargon list has BD, “twice a day”. BID is one of a set: TID is three times a day and QID four. The authorities differ on the Latin forms. In a 2006 editorial in Anesthesia Progress, Joel Weaver listed b.i.d. among the Latin abbreviations that modern, safe prescribing discourages; ISMP’s 2019 guidelines for electronic prescribing accept BID as a frequency abbreviation when it is written in capitals, without spaces or periods.
Also searched as: b.i.d., bid meaning, bid medical abbreviation, bis in die.
These pages explain what medical abbreviations and symbols stand for. They are not medical advice and give no doses: a pharmacist or prescriber can explain what any label means for you.
Look-alikes: BIW and BT
Two other abbreviations are flagged because they get read as BID. ISMP’s list of error-prone abbreviations gives BIW (2 times a week) as “mistaken as 2 times a day”; its recommended wording is “2 times weekly”. ISMP’s 2015 list included BT, for bedtime, as “mistaken as BID”, and the Minnesota Board of Pharmacy notes the same risk. For bedtime, see QHS.
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Sources
- b.i.d. (American Heritage Dictionary entry), The American Heritage Dictionary of the English Language, Fifth Edition, HarperCollins Publishers, b.i.d., abbr.
- Appendix B: Some Common Abbreviations, MedlinePlus, U.S. National Library of Medicine, BID
- Partial list of prescription abbreviations, Minnesota Board of Pharmacy, Partial list of prescription abbreviations, Minnesota Board of Pharmacy, b.d./b.i.d.; bis
- ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations (2024), 2024 edition, Institute for Safe Medication Practices, Abbreviations for Frequency/Instructions for Use: TIW, BIW
- ISMP's List of Error-Prone Abbreviations, Symbols, and Dose Designations, 2015 edition, Institute for Safe Medication Practices, BT
- Guidelines for Safe Electronic Communication of Medication Information (2019), 2019 edition, Institute for Safe Medication Practices, Frequency abbreviations
- It’s time to throw out old-fashioned Latin abbreviations, Joel M. Weaver, Anesthesia Progress 2006;53(1):1–2, American Dental Society of Anesthesiology, Paragraph 4
- Meaning of abbreviations and jargon, Lincolnshire Partnership NHS Foundation Trust, carers’ support pages, Lincolnshire Partnership NHS Foundation Trust, Abbreviations, B
Last reviewed September 30, 2026 by Rory Hansen. How we research