Abbrev. Meaning Latin (or New Latin) origin
a.c. before meals ante cibum
a.d., ad, AD right ear auris dextra
a.m., am, AM morning ante meridiem
a.s., as, AS left ear auris sinistra
a.u., au, AU both ears together or each ear aures unitas or auris uterque
b.d.s, bds, BDS 2 times a day bis die sumendum
b.i.d., bid, bd twice a day / twice daily / 2 times daily bis in die
gtt., gtt drop(s) gutta(e)
h., h hour hora
h.s., hs at bedtime or half strength hora somni
ii two tablets duos doses
iii three tablets trēs doses
n.p.o., npo, NPO nothing by mouth / not by oral administration nil per os
o.d., od, OD once a day omne in die
right eye oculus dexter
o.s., os, OS left eye oculus sinister
o.u., ou, OU both eyes oculus uterque
p.c. after food post cibum
p.m., pm, PM afternoon or evening post meridiem
p.o., po, PO orally / by mouth / oral administration per os / nonstandard form per orem
p.r., pr, PR rectally per rectum
p.r.n., prn, PRN as needed, (also Pertactin - a key antigen of ac.Pertussis vaccine) pro re nata
q. every quaque
q.1.d., q1d every day quaque die
q.1.h., q1h every hour quaque hora
q.2.h., q2h every 2 hours quaque secunda hora
q.4.h., q4h every 4 hours quaque quarta hora
q.6.h., q6h every 6 hours quaque sexta hora
q.8.h., q8h every 8 hours quaque octava hora
q.a.m., qAM, qam every morning quaque ante meridiem
q.d., qd every day / daily quaque die
q.h.s., qhs every night at bedtime quaque hora somni
q.d.s, qds, QDS 4 times a day quater die sumendum
q.i.d, qid 4 times a day quater in die
q.h., qh every hour, hourly quaque hora
q.o.d., qod every other day / alternate days quaque altera die
q.p.m., qPM, qpm every afternoon or evening quaque post meridiem
q.s., qs a sufficient quantity (enough) quantum sufficiat
Rx, Rx prescription recipe
Sig., S. directions signa
Stat. immediately, with no delay, now statim
t.d.s, tds, TDS 3 times a day ter die sumendum
t.i.d., tid 3 times a day ter in die
u.d., ud as directed ut dictum