Near catastrophe following prescription misinterpretation

I was shocked over the weekend when a nurse mistook the q.d in a prescription for q.i.d and administered a drug meant for once daily dosing four times to a very ill patient. Lucky enough, one of the 3 house officers in my team discovered it, and raised an alarm.

It turns out she never knew what q.d meant. She said she knew o.d meant once daily, but always thought q.d was another way of writing q.i.d. Fortunately enough, the patient in question survived the onslaught.

This got me thinking that things we know and take for granted might afterall not be well known by all in the healthcare team. So I decided to write out, for the benefit of all, the meanings of these often used prescription abbreviations.

Prescription abbreviations: qd, bid, tid, qid, q_h

If seen on a prescription, these abbreviations are a number of age-old abbreviations of Latin terms used traditionally in prescriptions to specify the frequency with which medications should be taken. They request medications to be administered for the particular number of times indicated. The abbreviations are sometimes written without a period in capital letters as "QD, BID, etc". However it is written, whether in small or capital letter, it still means the same thing.

The complete meanings are:

• q.d. (qd or QD) - once a day; q.d. stands for "quaque die" (which means, in Latin, once a day).
• b.i.d. (bid or BID) - twice a day; b.i.d. stands for "bis in die" (in Latin, twice a day).
• t.i.d. (or tid or TID) - three times a day; t.i.d. stands for "ter in die" (in Latin, 3 times a day).
• q.i.d. (or qid or QID) - four times a day; q.i.d. stands for "quater in die" (in Latin, 4 times a day).
• q_h: If a medicine is to be taken every so-many hours, it is written "q_h"; the "q" standing for "quaque" and the "h" indicating the number of hours. So, for example, "2 caps q4h" means "Take 2 capsules every 4 hours."