On a prescription, "qd" or "q.d." refers to taking a medication once daily, derived from Latin. This abbreviation can also appear in uppercase without periods as "QD." It is part of a traditional set of Latin abbreviations used to indicate how frequently medications should be taken.Other similar abbreviations include:- "b.i.d." (or "bid" or "BID") meaning twice daily, originating from the Latin phrase meaning twice a day.- "t.i.d." (or "tid" or "TID") indicates three times daily, based on the Latin for three times a day.- "q.i.d." (or "qid" or "QID") means four times daily, from the Latin meaning four times a day.For medications to be taken at specific hourly intervals, "q_h" is used, where "q" stands for "every" and "h" represents the number of hours. For instance, "2 caps q4h" instructs to take 2 capsules every 4 hours.
