BIW

Medical abbreviation · Prescription

BIW
Stands forTwice a week
CategoriesMedical

BIW stands for Twice a week, a prescription abbreviation.

Dosing frequency of two times per week, used for some hormone patches, vitamin D regimens and injectables. ISMP lists it as error-prone because it has been mistaken for "2 times a day", and recommends writing "2 times weekly" or naming the days.

Example: Estradiol 0.05 mg patch, apply BIW (Sunday and Wednesday).

Usage notes

Also written biw. Estradiol patches such as Vivelle-Dot and Climara Pro are designed for twice-weekly or once-weekly changes, respectively, so confusing the frequency affects hormone exposure. Pharmacists often print the specific days on the label to prevent mix-ups.

More prescription abbreviations

  • AC – Ante cibum (before meals)
  • ACHS – Ante cibum et hora somni (before meals and at bedtime)
  • ad lib. – Ad libitum (at one's pleasure)
  • ATC – Around the clock
  • bd – Bis die (twice a day)
  • BID – Bis in die (twice a day)
  • BT – Bedtime
  • cc – Cubic centimeter
  • c̄ – Cum (with)
  • D/C – Discontinue
  • DAW – Dispense as written
  • Disp – Dispense

See all 77 prescription abbreviations →

Edited by the AbbreviationList.com team. Spotted an error or a missing meaning? Contact us.

This entry is for general education and is not medical advice. Abbreviation use varies between institutions; always confirm in context.