o.u.
both eyes
oz
ounce
per
by or through
p.c.
after meals
p.m.
evening or afternoon
prn
as needed
p.o.
by mouth or orally
p.r.
by rectum
pulv.
powder
q
every
q.a.d.
every other day
q.a.m.
every day before noon
q.h.
every hour
q.h.s.
every night at bedtime
q.1h
every 1 hour
q.d.
every day
q.i.d.
4x a day
q.o.d.
every other day
qqh
every four hours
q.s.
a sufficient quantity