BID Medical Abbreviation: Correct Usage (No Periods)

BID (or b.i.d. in older notation) stands for Latin bis in die — "twice daily."

Modern Standard

• No periods: BID (preferred by ISMP, The Joint Commission, and major style guides).
• Periods (b.i.d.) are outdated and increase misreading risk (e.g., confused with BID vs. B.I.D. vs. bid).

Related Frequency Abbreviations

Abbreviation	Latin	Meaning
QD / qd	quaque die	Once daily
TID / tid	ter in die	Three times daily
QID / qid	quater in die	Four times daily
HS / hs	hora somni	At bedtime

Best practice: Write out "twice daily" in patient-facing instructions to avoid ambiguity.