Medical Definition of q.d. (on prescription)
q.d. (on prescription): Seen on a prescription, q.d. (or qd) means one a day (from the Latin quaque die). The abbreviation is sometimes written without a period in capital letters as "QD". However it is written, it is one of a number of hallowed abbreviations of Latin terms that have been traditionally used in prescriptions to specify the frequency with which medicines should be taken.
Other examples include:
Last Editorial Review: 5/13/2016
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