If your prescription is labeled "b.i.d.," you should take it twice daily.
If the label on your prescription drug says "b.i.d.," you should take it two times daily. The letters stand for "bis in die," which is Latin for twice a day.
Significance
The abbreviation "b.i.d." sometimes is written or typed without periods either in lowercase letters as "bid" or in capital letters as "BID." Regardless of the way in which it is written, "b.i.d." is one of a number of abbreviations of Latin terms used by pharmacists.
Fun Fact
Other abbreviations of Latin used by pharmacists include "q.d.," which stands for "quaque die" or once a day, "t.i.d." for "ter in die" or three times a day, and "q.i.d." for "quater in die" or four times a day. If a medicine is to be taken every six hours, it is written "q6h." The "q" stands for "quaque" and the "h" for "hora."
History
The art of prescription-writing is an ancient one. Latin was used because it is a universal language. The ancients always started their prescription-writing with a prayer to the gods for a successful cure. The symbol Rx symbolizes the appeal to the gods.
