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Medical Abbreviations on Pharmacy Prescriptions

Medically reviewed on Jan 05, 2016 by L. Anderson, PharmD

BID, PO, XL, APAP, QHS, or PRN: Have you ever wondered what these odd, encrypted medical abbreviations mean on your prescription? Medical terminology is difficult enough, but how do you interpret these prescription directions written in code? Luckily you don’t have to; it’s the pharmacist’s job to put the medical abbreviation in plain english on your medication label. But there may be more to know about this shorthand than meets the eye.

Looking for the list of medical abbreviations? Click here to access the table below

Apothecary prescription abbreviations, like the ones you might see written by your doctor on your prescription or a hospital medication order, can be a common source of confusion for healthcare providers, too. In fact, an unclear, poorly written or wrong medical abbreviation that leads to misinterpretation is one of the most common and preventable causes of medication errors. All abbreviations can increase the risk for incorrect interpretation and should be used with caution in the healthcare setting.

Healthcare agencies, such as the Food and Drug Administration (FDA), The Joint Commisssion, and the Institute for Safe Medication Practices (ISMP) have made it a priority to communicate information about confusing abbreviations and medical shorthands. Health care facilities and practitioners are expected to take action and set internal standards to prevent these common - and potentially dangerous - medical errors.

Don’t Computers Solve The Problem With Abbreviations?

Some of the typed or computer-generated abbreviations, prescription symbols, and dose designations can still be confused and lead to mistakes in drug dosing or timing. In addition, when these abbreviations are unclear, extra time must be spent by pharmacists or other healthcare providers trying to clarify their meanings, which can delay much-needed treatments. Historically, poor penmanship and lack of standardization was the root cause of many of the prescription errors. Today, many prescriptions are now submitted via electronic prescribing (e-prescribing), electronic medical records (EMRs), and computerized physician order entry (CPOE), which has helped to lower the rates of these medical errors. However, discrepancies between structured and free-text fields in electronic prescriptions are common and can lead to medical errors and possible patient harm.

Drug Name Abbreviations

Drug names may often be abbreviated, too. For example, complicated treatment regimens, like cancer treatment protocols, may be written with drug name abbreviations. As reported by the FDA, a prescription with the abbreviation “MTX” has been interpreted as both methotrexate (used for rheumatoid arthritis) or mitoxantrone (a cancer drug), and “ATX” was understood to be the shorthand for zidovudine (an HIV drug) or azathioprine (an immunosuppressant drug). These types of errors can be linked with severe patient harm.

Confusing Numbers

Numbers can lead to confusion and drug dosing errors, too. As an example, a prescription for “furosemide 40 mg Q.D.” (40 mg daily) was misinterpreted as “QID” (40 mg four times a day), leading to a fatal medical error. Another example has to do with drug dosage units: doses in micrograms should always have the unit spelled out, because the abbreviation “µg” (micrograms) can easily be misread as “mg” (milligrams), creating a 1000-fold overdose.

Numbers can also be misinterpreted with regards to decimal points. As noted in the Joint Commission's Do Not Use List, a trailing zero (for example, 5.0 mg) can be misinterpreted as “50” mg leading to a 10-fold overdose. Instead the prescriber should write “5 mg” with no trailing zero or decimal point after the number. Also, the lack of a leading zero, (for example, .9 mg) can be misread as “9” mg; instead the prescriber should write out “0.9 mg” to clarify the strength.

Modified-Release Technology

Common abbreviations are often used for modified-release types of technology for prescription drugs, although no true standard exists for this terminology. Many drugs exist in special formulation as tablets or capsules - for example as ER, XR, and SR - to slow absorption or alter where the dissolution and absorption occurs in the gastrointestinal tract. Timed-release technology allows drugs to be dissolved over time, allows more steady blood concentrations of drugs, and can lower the number of times a drug must be taken per day compared to immediate-release (IR) formulations. Enteric-coated formulations, such as enteric-coated aspirin, help to protect the stomach by allowing the active ingredient to bypass dissolution in the stomach and instead dissolve in the intestinal tract. See the table for timed-release technology abbreviations.

Ways For Health Care Providers To Avoid Medication Errors

  • Completely write out the prescription, including the drug name and dosage regimen. The full dosage regimen includes the dose, frequency, duration, and route of administration of the drug to be administered.
  • When writing out a dose, do not use a trailing zero and do use a leading zero.
  • For veterinarians, when calling in or writing out a human drug prescription for animals, verbally state or write out the entire prescription because some pharmacists may be unfamiliar with veterinary abbreviations.
  • Consider using a computerized prescription system to minimize misinterpretation of handwriting.
  • Institutions should educate healthcare providers and other employees on proper use of abbreviations.
  • Report adverse events that stem from medication errors or abbreviations errors to the FDA.

Practitioners, including physicians, nurses, pharmacists, physician assistants and nurse practitioners, should be very familiar with the abbreviations used in medical practice and in prescription writing. All drug names, dosage units, and directions for use should be written clearly to avoid misinterpretation. Pharmacists should be included in teams that develop EMRs and e-prescribing tools. According to the Joint Commission, health care organizations can develop their own internal standards for medical abbreviations, use a published reference source with consistent terms, and should ensure to avoid multiple abbreviations for the same word. However, internal enforcement and consistency are always the key.

What Can You As a Patient Do?

  • Ask your doctor how you are supposed to take your medication before you leave the office, and write it down for future reference.
  • If you receive a prescription with unusual or unexpected directions, be sure to double check with your pharmacist or doctor.
  • FDA encourages all healthcare providers, patients and consumers to report medication errors to the FDA Medwatch Program so that the FDA can be made aware of potential problems and provide effective interventions that will minimize further errors. Timely prevention of medical errors can save a patient’s life.

Table: Common Medical and Prescription Abbreviations

Abbreviation Meaning / Intended Meaning Notes About Confusion Category
1/2NS one-half normal saline (0.45%)   drug or class name
5-ASA 5-aminosalicylic acid Better to spell out drug name; can be misinterpreted as five tablets of aspirin per FDA drug or class name
a before   time
A.M. morning   time
aa of each   measurement
AAA abdominal aortic aneurysm (called a "triple-A") Can be misinterpreted as 'apply to affected area' medical condition
AAA apply to affected area Can be misinterpreted as 'abdominal aortic aneurysm' route of administration
ac before meals   time
achs before meals and at bedtime   time
AD right ear   route of administration
ad lib freely; as much as desired   time
ad sat. to saturation   other
ad. to; up to Caution not to confuse with AD (meaning right ear) measurement
ALT alanine aminotransferase   lab
alt. alternate   time
alt. h. every other hour   time
am, A.M. in the morning; before noon   time
amp ampule   dosage form
amt. amount   measurement
ant. anterior   other
ante before   time
ap before dinner   time
APAP acetaminophen Better to spell out drug name "acetaminophen" drug or class name
aPTT activated partial thromboplastin   lab
AQ, aq water   other
a.s., AS left ear   route of administration
ASA aspirin Better to spell out drug name "aspirin" drug or class name
AST aspartate aminotransferase   lab
ATC around the clock   time
AU each ear; both ears   route of administration
AZT zidovudine Better to spell drug name out; can be misinterpreted as azathioprine per FDA drug or class name
Ba barium   drug or class name
BCP birth control pills   drug or class name
Bi bismuth   drug or class name
bid, BID twice a day   time
BM bowel movement   other
BMI body mass index   vitals
bol bolus   measurement
BP blood pressure   vitals
BPH benign prostatic hypertrophy   medical condition
BS blood sugar   lab
BSA body surface area   vitals
BT bedtime In U.S., 'hs' or 'HS' is more commonly used for bedtime time
c with   other
C.C. chief complaint   other
c/o complaints of   other
C&S culture and sensitivity   lab
CABG coronary artery bypass graft   other
CaCO3 calcium carbonate   drug or class name
CAD coronary artery disease   medical condition
CAP cancer of the prostate Do not confuse with "capsule" medical condition
cap. capsule Do not confuse with "cancer of the prostate" dosage form
CBC complete blood count   lab
cc cubic centimeter Can also mean "with food" measurement
CD controlled delivery   drug release technology
CF cystic fibrosis   medical condition
cm centimeter   measurement
CNS central nervous system   other
conc concentrated   other
CPZ Compazine Better to spell drug name out; can be misinterpreted as chlorpromazine per FDA drug or class name
CR controlled-release   drug release technology
cr, crm cream   dosage form
CV cardiovascular   other
CXR chest x-ray   lab
D/C, dc, disc. discontinue OR discharge Multiple possible meanings; spell out instead of using "D/C" other
D5/0.9 NaCl 5% dextrose and normal saline solution (0.9% NaCl)   drug or class name
D5 1/2/NS 5% dextrose and half normal saline solution (0.45% NaCl)   drug or class name
D5NS dextrose 5% in normal saline (0.9%)   drug or class name
D5W 5% dextrose in water   drug or class name
DAW dispense as written   other
DBP diastolic blood pressure   lab
dil. diluted   other
disp dispense   other
div divide   other
DKA diabetic ketoacidosis   medical condition
dL deciliter   measurement
DM diabetes mellitus   medical condition
DO Doctor of Osteopathic Medicine   medical specialty
DOB date of birth   other
DPT diphtheria-pertussis-tetanus Better to spell out vaccine name; can be misinterpreted as Demerol-Phenergan-Thorazine per FDA drug or class name
DR delayed-release   drug release technology
DVT deep vein thrombosis   medical condition
DW dextrose in water, diabetes mellitus or distilled water Multiple possible meanings; spell out instead of using "DW" other
EC enteric-coated   drug release technology
EENT Eye, Ear, Nose, and Throat   Medical Specialty
elix. elixir   dosage form
emuls. emulsion   dosage form
ER extended-release Can also mean "emergency room" drug release technology
ER emergency room Can also mean "extended-release" other
ETOH ethyl alcohol   drug or class name
F Fahrenheit   lab
f or F female   other
FBS fasting blood sugar   lab
FDA Food and Drug Administration   other
Fe Iron   drug or class name or lab
FFP fresh frozen plasma   drug or class name
fl or fld fluid   measurement
ft foot   measurement
G, or g, or gm gram "g" is preferred symbol measurement
garg gargle   route of administration
GERD gastroesophageal reflux disease   medical condition
GI gastrointestinal   other
gr. grain Apothecary measurement (obsolete and may be misinterpreted as gram; do not use) measurement
GTT glucose tolerance test Can be confused with gtt for drops lab
gtt, gtts drop, drops Can be confused with GTT for glucose tolerance test measurement
GU genitourinary   other
guttat. drop by drop   measurement
h, or hr. hour   time
h/o history of   other
H&H hematocrit and hemoglobin   lab
H2 histamine 2   other
H20 water   other
HAART highly active antiretroviral therapy   drug or class name
HCT, or Hct hematocrit   lab
HCT hydrocortisone Better to spell out drug name; can be misinterpreted as hydrochlorothiazide per FDA drug or class name
HCTZ hydrochlorothiazide Better to spell out drug name; can be misinterpreted as hydrocortisone per FDA drug or class name
HR heart rate   vitals
HS half-strength better to spell out; do not mistake for "bedtime" measurement
hs or HS at bedtime, hours of sleep Do not misinterpret as 'half-strength' time
HTN hypertension   medical condition
hx history   other
IBW ideal body weight   lab
ID intradermal OR infectious disease Multiple possible meanings; spell out word instead of using "ID" route of administration; other
IJ injection better to spell out 'injection' route of administration
IM intramuscular   route of administration
IN intranasal   route of administration
inf infusion   route of administration
inj. injection   route of administration
instill. instillation   route of administration
IP intraperitoneal   route of administration
IR immediate-release   drug release technology
IU international unit Mistaken as IV (intravenous) or 10 (ten); Instead spell out "units" per Joint Commission's "Do Not Use" List of Abbreviations  
IUD intrauterine device   dosage form
IV intravenous   route of administration
IVP intravenous push Could be confused with 'intravenous pyelogram' route of administration
IVPB intravenous piggyback   route of administration
J joule   lab
K potassium   drug or class name
KOH potassium hydroxide   drug or class name
L liter   measurement
LA long-acting   drug release technology
lab laboratory   other
lb. pound   measurement
LDL low-density lipoprotein   lab
LFT liver function tests   lab
Li lithium   drug or class name
liq. liquid   dosage form
LMP last menstrual period   other
lot lotion   dosage form
LPN licensed practical nurse   medical specialty
LR lactated ringer (solution)   drug or class name
mane in the morning   time
mcg microgram Can be misinterpreted to mean "mg" or milligram, better to spell out 'microgram' measurement
MD medical doctor   medical specialty
MDI metered-dose inhaler   dosage form
mEq milliequivalent   measurement
mEq/L milliequivalent per liter   measurement
Mg magnesium   drug or class name
mg milligram   measurement
MgSO4 magnesium sulfate May be confused with "MSO4" (morphine sulfate), spell out "magnesium sulfate" - Joint Commission's "Do Not Use" List of Abbreviations drug or class name
mL milliliter   measurement
mm millimeter   measurement
mm of Hg millimeters of mercury   measurement
mMol millimole   measurement
MMR measle-mumps-rubella (vaccine)   drug or class name
mol wt molecular weight   measurement
MR modified-release   drug release technology
MS morphine sulfate or magnesium sulfate Can mean either morphine sulfate or magnesium sulfate, spell out drug name - Joint Commission's "Do Not Use" List of Abbreviations drug or class name
MSO4 morphine sulfate May be confused with "MgSO4"; instead spell out "morphine sulfate" - Joint Commission's "Do Not Use" List of Abbreviations drug or class name
n or noct. in the night   time
N/A not applicable   other
N/V, N&V nausea and vomiting   other
Na sodium   lab or drug or class name
NAS intranasal   route of administration
NDC National Drug Code   other
NGT nasogastric tube   route of administration
NH3 ammonia   other
NKA no known allergies   other
NKDA no known drug allergies   other
noct. maneq. night and morning   time
NP nurse practitioner   medical specialty
NPO, n.p.o. nothing by mouth Preferred by AMA to spell out "nothing by mouth" route of administration
NS normal saline   drug or class name
NSAID nonsteroidal anti-inflammatory drug   drug or class name
NTE not to exceed   other
O2 oxygen   other
OC oral contraceptive   drug or class name
o.d., OD right eye Can also mean "overdose" or "once daily"; better to spell out route of administration, ophthalmic abbreviations
o.d. once per day Preferred in the UK; Can also mean "overdose" or "right eye"; better to spell out time
OJ orange juice   other
OM otitis media   medical condition
o.s., OS left eye   route of administration, ophthalmic abbreviations
OTC over-the-counter   other
o.u., OU both eyes   route of administration, ophthalmic abbreviations
oz ounce   measurement
p after   time
p.r.n., prn as needed   time
PA physician assistant   medical specialty
pc after meals   time
PCA patient-controlled analgesia   other
PE physical exam, pulmonary embolism   other
per by or through   route of administration
per neb by nebulizer   route of administration
per os by mouth, orally AMA prefers to spell out "by mouth" or "orally"; can be mistaken as "os" meaning left eye per FDA route of administration
PFT pulmonary function tests   lab
pH hydrogen ion concentration   other
PharmD Doctor of Pharmacy   medical specialty
PM evening   time
PMH past medical history   other
PO, p.o. orally or by mouth AMA prefers to spell out "by mouth" or "orally" route of administration
PR, p.r. per the rectum   route of administration
PT prothrombin time   lab
PTT partial thromboplastin time   lab
pulv powder   dosage form
PV per the vagina   route of administration
q every   time
q.s., qs as much as needed; a sufficient quantity   measurement
q12h every 12 hours   time
qd, q1d daily   time
q2h every 2 hours   time
q3h every 3 hours   time
q4h every 4 hours   time
q6h every 6 hours   time
q6PM, etc every evening at 6 PM   time
q8h every 8 hours   time
qam every morning   time
qd, QD every day Mistaken as q.i.d; Instead write "daily" or "every day" per Joint Commission's "Do Not Use" List of Abbreviations time
qh every hour   time
qhs each night at bedtime Can be confused with "qh" meaning every hour; better to spell out time
qid four times a day   time
qn Nightly or at bedtime Not commonly used in U.S.; 'hs' more common for bedtime time
qod, QOD, q.o.d every other day Can be mistaken as qd (daily) or qid (four times daily); Instead spell out "every other day" per Joint Commission's "Do Not Use" List of Abbreviations time
q.s. ad add sufficient quantity to make   measurement
RA rheumatoid arthritis   medical condition
RDA recommended daily allowances   other
RE right eye   route of administration, ophthalmic abbreviations
rep repeats   time
RN registered nurse   medical specialty
RPh pharmacist   medical specialty
Rx prescription   other
s without   other
s.o.s. if necessary   other
sa according to the art; best practice   other
SA sustained action   drug release technology
SBP systolic blood pressure   vital sign
SID Used ONLY in Veterinary medicine to mean "once daily" Can be confused to mean BID (twice daily) and QID (four times daily); pharmacists should clarify abbreviations with DVM, if needed. time; used in Veterinary medicine ONLY
sig codes medical or prescription abbreviations   other
Sig. write on label   other
SL, s.l. sublingual, under the tongue   route of administration
SNRI serotonin/norepinephrine reuptake inhibitor   drug or class name
SOB shortness of breath   other
sol solution; in solution   dosage form
sp gr specific gravity   lab
SQ, SC, sub q subcutaneously Use caution as "SC" can be mistaken for "SL," meaning sublingual per FDA route of administration
SR sustained release   drug release technology
ss sliding scale (insulin) OR 1/2 (apothecary; obsolete) Use caution; can be misinterpreted; better to spell out "sliding scale" or "one-half" other
SSI Sliding scale insulin   other
SSRI sliding scale regular insulin OR selective serotonin reuptake inhibitor Spell out words to avoid confusion other
stat immediately   time
STD sexually transmitted diseases   medical condition
sup. superior   other
supf. superficial   other
supp suppository   dosage form
susp suspension   dosage form
syr. syrup   dosage form
T temperature   vital sign
tab tablet   dosage form
tbsp tablespoon   measurement
TIA transient ischemic attack   medical condition
TID, t.i.d. three times a day   time
tid ac three times a day before meals   time
TIN, t.i.n. three times a night   time
tinct., tr tincture   dosage form
TIW, tiw 3 times a week Spell out; can be confused with TID (three times a day) time
top. topical   route of administration
TO telephone order    
TPN total parenteral nutrition   drug or class name
TR timed-release   drug release technology
troche lozenge   dosage form
TSH thyroid stimulating hormone   lab
tsp teaspoon   measurement
Tx treatment   other
U or u unit Mistaken as the number "0" (zero), the number "4" (four), or "cc". Prescriber should instead spell out "unit" per Joint Commission's "Do Not Use" List of Abbreviations measurement
UA urinalysis   lab
ud, ut dict, UD as directed   other
ung ointment   dosage form
UTI urinary tract infection   medical condition
vag, pv via the vagina   route of administration
VLDL very low density lipoprotein   lab
vol % volume percent   measurement
vol. volume   measurement
w/o without   other
w/v weight in volume   measurement
WBC white blood cell   lab
WNL within normal limits   lab
wt. weight   vital sign
x multiplied by   other
XL extended-release   drug release technology
XR extended-release   drug release technology
XT extended-release   drug release technology
yo years old   other
yr year   time
Zn zinc   drug or class drug or class name
μEq microequivalent   measurement
μg, mcg microgram μg or mcg can be misinterpreted as "mg", better to spell out 'microgram' measurement
μL microliter   measurement

Further Reading:

Recommended for you


  1. Taber’s Medical Abbreviations. Tabers Online. Accessed December 23, 2015 at
  2. The Joint Commission. Patient Safety and Performance Measurement Fact Sheets. Facts About the Official “Do Not Use” List of Abbreviations. June 30, 2015. Accessed December 23, 2015 at
  3. Glassman P. The Joint Commission's “Do Not Use” List: Brief Review (NEW) In: Making Health Care Safer II: An Updated Critical Analysis of the Evidence for Patient Safety Practices. Rockville (MD): Agency for Healthcare Research and Quality (US); 2013 Mar. (Evidence Reports/Technology Assessments, No. 211.) Chapter 5. Accessed December 21, 2015 from
  4. Mahumud A, Phillips J, Holquist C. Stemming drug errors from abbreviations. FDA Safety Page. Drug Topics. July 1, 2002. Accessed December 23, 2015 at
  5. FDA. MedWatch: The FDA Safety Information and Adverse Event Reporting Program
  6. FDA Consumer Updates. FDA and ISMP Work to Prevent Medication Errors. March 29, 2012. Accessed December 23, 2015 at
  7. FDA. Animal and Veterinary. A Microgram of Prevention is Worth a Milligram of Cure: Preventing Medication Errors in Animals. October 28, 2015. Accessed December 18, 2015 at