Definition of qid (on prescription)
qid (on prescription): Seen on a prescription, qid (or q.i.d.) means 4 times a day (from the Latin quater in die). The abbreviation qid or q.i.d. is also sometimes written without a period in capital letters as "QID". 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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