620 APPENDIX E• Abbreviations and SymbolsDiscontinued Abbreviations
The Joint Commission (JC) and the Institute for Safe Medication Practices (ISMP) report that the following
abbreviations are commonly misinterpreted and have resulted in harmful medical errors. Both organizations have
compiled a comprehensive “Do Not Use” list (available on their websites) for health-care providers.
To prevent harmful medical errors, both organizations recommend discontinuance of these abbreviations. Instead
the abbreviations should be written out. Nevertheless, some of the abbreviations on the “Do Not Use” list are still
used by health-care providers. A selected number are listed below.Abbreviation Meaning
Medication and Therapy Time Schedule
a.c. before meals
b.i.d. twice a day
hs half strength
h.s. at bedtime
NPO, n.p.o. nothing by mouth
p.c. after meals
p.o. by mouth (orally)
p.r.n. as required
qAM every morning
q.d. every day
q.h. every hour
q.2h. every 2 hours
q.i.d. four times a day
q.o.d. every other day
qPM every evening
t.i.d. three times a day
Other Related Abbreviations
AD right ear
AS left ear
AU both ears
cc cubic centimeter; same as milliliter (1/1,000 of a liter)
Use mLfor millilitersor write out the meaning.
dc, DC, D/C discharge; discontinue
OD right eye
OS left eye
OU both eyes
subcu, Sub-Q, subQ subcutaneous (injection)
U unit3971_App E_613-621 13/02/14 11:26 AM Page 620