Medical Prescription - Rx

A medical prescription is an order usually in written form by a qualified health care professional or other therapist for the treatment to be provided to their patient. Prescriptions are typically handwritten on preprinted prescription forms, or may alternatively be using computer these days. The prescription should contain the name and address of the prescribing doctor and any other legal requirement such as registration number of the physician. What is unique for each prescription is the name of the patient, date, the details of the medication and the directions for taking them. Last but not the least the prescription should be appropriately signed by the physician prescribing it.

The symbol "Rx" meaning "prescription" is a transliteration of a symbol. There are various theories as to the origin of this symbol but in literal terms, "Rx" indicates an instruction "to take" what is specified in the prescription. The word "prescription" can also be decomposed into "pre" and "script" and in literal terms means, "to write before" a drug can be prepared.


Who Can Write Prescriptions
In the United States, physicians, veterinarians, dentists, and podiatrists can issue prescriptions. Some states may allow optometrists to issue eyeglass prescriptions for corrective eyeglasses though technically these cannot be termed as medical prescriptions. Even nurse practitioners, physician assistants, optometrists, homeopathic physicians, registered pharmacists, and doctors of some other branches of medicine do have the authority to prescribe.

Non-Prescription Drug Prescriptions
Prescriptions are also used for things that are not strictly regulated as a prescription drug. Doctors will often give non-prescription drugs out as prescriptions because drug benefit plans may reimburse the patient only if the over-the-counter medication is taken under the direction of a doctor. Conversely, if a medication is available over-the-counter, doctors may ask patients if they want it as a prescription and possibly incur a pharmacist's dispensing fee or whether they want to get it themselves at a lower price. If the patient wants the medication not under prescription, the doctor is usually careful to give the medication name to the patient on a blank piece of paper to avoid any confusion with a prescription.

What are over-the-counter drugs?
Over-the-counter or OTC substances are drugs and other medical remedies that may be sold without a prescription and without a visit to a medical professional, in contrast to prescription only medicines (POM). As a general rule, over-the-counter drugs have to be primarily used to treat a condition that does not require the direct supervision of a doctor and must be proven to be reasonably safe and well tolerated with little abuse potential.

List of prescription abbreviations
This is a list of all abbreviations used in prescriptions. Capitalization and the use of a period is a matter of style. In the attached list, Latin is not capitalized whereas English acronyms are. The period is used wherever there are letters omitted in the abbreviation.

aa (ana) - of each
ad - to, up to
a.c. (ante cibum) - before meals
a.d. (aurio dextra) - right ear
ad lib. (ad libitum) - use as much as one desires; freely
admov. (admove) - apply
agit (agita) - stir/shake
alt. h. (alternis horis) - every other hour
a.m. (ante meridiem) - morning, before noon
amp - ampule
amt - amount
aq (aqua) - water
a.l., a.s. (aurio laeva, aurio sinister) - left ear
A.T.C. - around the clock
a.u. (auris utrae) - both ears
bis (bis) - twice
b.i.d. (bis in die) - twice daily
B.M. - bowel movement
bol. (bolus) - a large pill
B.S. - blood sugar
B.S.A - body surface areas
cap., caps. (capsula) - capsule
c (cum) - with (usually written with a bar on top of the "c")
c (cibos) - food
cc - cubic centimeter; also means "with food" (cum cibos)
cf - with food
D5W - dextrose 5% solution (sometimes written as D5W)
D5NS - dextrose 5% in normal saline (0.9%)
D.A.W. - dispense as written
dc, D/C, disc - discontinue
dieb. alt. (diebus alternis) - every other day
dil. - dilute
disp. - dispense
div. - divide
d.t.d. (dentur tales doses) - give of such doses
D.W. - distilled water
elix. - elixir
e.m.p. (ex modo prescripto) - as directed
emuls. (emulsum) - emulsion
et - and
ex aq - in water
fl., fld. - fluid
ft. (fiat) - make; let it be made
g - gram
GI - gastrointestinal
gr - grain
gtt(s) (gutta(e)) - drop(s)
GU - genitourinary
H - hypodermic
h, hr - hour
h.s. (hora somni) - at bedtime
ID - intradermal
IM - intramuscular (with respect to injections)
inj. (injectio) - injection
IP - intraperitoneal
IV - intravenous
IVP - intravenous push
IVPB - intravenous piggyback
L.A.S. - label as such
LCD - coal tar solution
lin (linimentum) - liniment
liq (liquor) - solution
lot. - lotion
M. (misce) - mix
m, min (minimum) - a minimum
mcg - microgram
mEq - milliequivalent
mg - milligram
mist. (mistura) - mix
mitte (mitte) - send
mL - millilitre
N&V, N/V - nausea and vomiting
nebul (nebula) - a spray
NKA. - no known allergies
NKDA - no known drug allergies
non rep. (non repetatur) - no repeats
NPO, n.p.o. (nil per os) - nothing by mouth
NS - normal saline (0.9%)
1/2NS - half normal saline (0.45%)
N.T.E. - not to exceed
o.d. (oculus dexter) - right eye
o.s. (oculus sinister) - left eye
o.u. (oculo utro) - both eyes
oz - ounce
per - by or through
p.c. (post cibum) - after meals
p.m. (post meridiem) - evening or afternoon
prn (pro re nata) - as needed
p.o. (per os) - by mouth or orally
p.r. - by rectum
pulv. (pulvis) - powder
q (quaque) - every
q.a.d. (quoque alternis die) - every other day
q.h. (quaque hora) - every hour
q.1h (quaque 1 hora) - every 1 hour; (can replace "1" with other numbers)
q.d. (quaque die) - every day
q.i.d. (quater in die) - four times a day
q.o.d. - every other day
q.s. (quantum sufficiat) - a sufficient quantity
R - rectal
rep., rept. (repetatur) - repeats
RL, R/L - Ringer's lactate
s (sine) - without (usually written with a bar on top of the "s")
s.a. (secundum artum) - use your judgment
SC, subc, subq, subcut - subcutaneous
sig - write on label
SL - sublingually, under the tongue
sol (solutio) - solution
s.o.s., si op. sit (si opus sit) - if there is a need
ss (semis) - one half
stat (statim) - immediately
supp (suppositorium) - suppository
susp - suspension
syr (syrupus) - syrup
tab (tabella) - tablet
tal., t (talus) - such
tbsp - tablespoon
troche (trochiscus) - lozenge
tsp - teaspoon
t.i.d. (ter in die) - three times a day
t.i.w. - three times a week
top. - topical
TPN - total parenteral nutrition
tr, tinc., tinct. - tincture
u.d., ut. dict. (ut dictum) - as directed
ung. (unguentum) - ointment
USP - United States Pharmacopoeia
vag - vaginally
w/o - without
X - times

To avoid ambiguity, the following abbreviations are not recommended:
  • a.u., a.d., a.s. - Latin for both, left and right ears; the "a" can be misread to be an "o" and interpreted to mean both, right or left eyes
  • d/c - can mean "discontinue" or "discharge"
  • h.s. - can mean half strength or "hour of sleep"
  • q.o.d. - meant "every other day" but the "o" can be interpreted as "." or "i" resulting in double or eight times the frequency
  • SC/SQ - meant "subcutaneous" but mistaken for "SL" for "sublingual"
  • TIW - meant 3 times a week but mistaken for twice a week
  • U - meant "units" but mistaken for "0", "4" or "cc" when poorly written; conversely cc can be mistaken for "U"
  • μg - meant "microgram" but mistaken for "mg"; this 1000-fold error can cause potentially fatal misunderstandings.

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