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Medical Abbreviations on Pharmacy Prescriptions

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on July 14, 2021.

BID, PO, XR, 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 common medical abbreviations? Click here to access Table 1 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) 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 confusing 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 in electronic prescriptions are common and can lead to medical errors and possible patient harm.

If you receive a prescription label with unclear and confusing directions, always call your doctor right away to check on the correct information.

Drug Name Abbreviations

Drug names may often be abbreviated, too. For example, complicated treatment regimens, like cancer treatment protocols or combination HIV regimens, 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). “ATX” was misunderstood to be the shorthand for zidovudine (AZT, 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 serious 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.

Trailing zeros on medication orders

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, where the zero follows a decimal point) 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 use “0.9 mg” to clarify the strength.

The Joint Commission notes an exception to the Trailing Zero warning. They state that a “trailing zero” may be used only where needed to demonstrate the level of precision of the value being reported, such as for laboratory results, imaging studies that report size of lesions, or catheter or tube sizes. It may not be used in medication orders or other medication-related documentation.

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.

Ways For Health Care Providers To Avoid Medication Errors

  • Completely write out (or select electronically) 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 an animal, verbally state or write out the entire prescription because some pharmacists may be unfamiliar with veterinary abbreviations.
  • Use a computerized prescription system and electronic delivery of prescriptions to minimize misinterpretation of handwriting.
  • Institutions should regularly educate and update healthcare providers and other employees on proper use of abbreviations.
  • Report adverse events that stem from medication errors or abbreviations errors to the FDA; these events can be used to further inform and expand recommendations for safety.

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 or evaluate 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. Internal enforcement, regular review and consistency are always the key.

What Can You Do As a Patient?

  • Ask your doctor how you are supposed to take your medication before you leave the office, and write it down for future reference.
  • Consider taking a trusted family member or friend to your medical appointments to help you to record important instructions.
  • If you receive a prescription with unusual, unexpected or confusing directions, be sure to double check with your doctor.
  • FDA encourages all healthcare providers, patients and consumers to report medication errors to the FDA Medwatch Program. The FDA is then aware of potential problems and can provide effective interventions that will minimize further errors. Timely prevention of medical errors can save a patient’s life.

Table 1: Common Medical Abbreviations

Note: This is not a complete list of medical abbreviations or error-prone abbreviations. Always speak with your healthcare provider for any questions related to medical abbreviations or terms.

Abbreviation Meaning / Intended Meaning Notes About Confusion
1/2NS one-half normal saline (0.45%) Normal saline (NS) is 0.9%, so one-half normal saline is 0.45%
5-ASA 5-aminosalicylic acid

Can be misinterpreted as five tablets of aspirin (per FDA).

Spell out full drug name.

a before  
A.M. morning  
aa of each  
AAA abdominal aortic aneurysm (called a "triple-A") Can be misinterpreted as 'apply to affected area'
AAA apply to affected area Can be misinterpreted as 'abdominal aortic aneurysm'
ac before meals  
achs before meals and at bedtime  
AD right ear  
ad lib freely; as much as desired  
ad sat. to saturation  
ad. to; up to Caution not to confuse with AD (meaning right ear)
ALT alanine aminotransferase  
alt. alternate  
alt. h. every other hour  
am, A.M. in the morning; before noon  
amp ampule  
amt. amount  
ant. anterior  
ante before  
ap before dinner  
APAP acetaminophen Spell out drug name "acetaminophen"
aPTT activated partial thromboplastin  
AQ, aq water  
a.s., AS left ear  
ASA aspirin Spell out drug name "aspirin"
AST aspartate aminotransferase  
ATC around the clock  
AU each ear; both ears  
AZT zidovudine

Can be misinterpreted as azathioprine (per FDA).

Spell out drug name.

Ba barium  
BCP birth control pills  
Bi bismuth  
bid, BID twice a day  
BM bowel movement  
BMI body mass index  
bol bolus  
BP blood pressure  
BPH benign prostatic hypertrophy  
BS blood sugar  
BSA body surface area  
BT bedtime In U.S., 'hs' or 'HS' is more commonly used for bedtime.
c with  
C.C. chief complaint  
c/o complaints of  
C&S culture and sensitivity  
CABG coronary artery bypass graft  
CaCO3 calcium carbonate  
CAD coronary artery disease  
CAP cancer of the prostate Do not confuse with "capsule"
cap. capsule Do not confuse with "cancer of the prostate"
CBC complete blood count  
cc cubic centimeters

May be mistaken as u (units) per ISMP.

Use mL instead of cc.

CD controlled delivery  
CF cystic fibrosis  
cm centimeter  
CNS central nervous system  
conc concentrated  
CPZ Compazine

Can be misinterpreted as chlorpromazine (per FDA).

Spell out drug name.

CR controlled-release  
cr, crm cream  
CV cardiovascular  
CXR chest x-ray  
D/C, dc, disc. discontinue OR discharge Multiple possible meanings; spell out instead of using "D/C"
D5/0.9 NaCl 5% dextrose and normal saline solution (0.9% NaCl)  
D5 1/2/NS 5% dextrose and half normal saline solution (0.45% NaCl)  
D5NS dextrose 5% in normal saline (0.9%)  
D5W 5% dextrose in water  
DAW dispense as written  
DBP diastolic blood pressure  
dil. diluted  
disp dispense  
div divide  
DKA diabetic ketoacidosis  
dL deciliter  
DM diabetes mellitus  
DO Doctor of Osteopathic Medicine  
DOB date of birth  
DPT diphtheria-pertussis-tetanus Better to spell out vaccine name; can be misinterpreted as Demerol-Phenergan-Thorazine per FDA
DR delayed-release  
DVT deep vein thrombosis  
DW dextrose in water, diabetes mellitus or distilled water Multiple possible meanings; spell out instead of using "DW"
EC enteric-coated  
EENT Eye, Ear, Nose, and Throat  
elix. elixir  
emuls. emulsion  
ER extended-release Can also mean "emergency room"
ER emergency room Can also mean "extended-release"
ETOH ethyl alcohol  
F Fahrenheit  
f or F female  
FBS fasting blood sugar  
FDA Food and Drug Administration  
Fe Iron  
FFP fresh frozen plasma  
fl or fld fluid  
ft foot  
G, or g, or gm gram "g" is preferred symbol
garg gargle  
GERD gastroesophageal reflux disease  
GI gastrointestinal  
gr. grain Apothecary measurement (obsolete and may be misinterpreted as gram; do not use)
GTT glucose tolerance test Can be confused with gtt for drops
gtt, gtts drop, drops Can be confused with GTT for glucose tolerance test
GU genitourinary  
guttat. drop by drop  
h, or hr. hour  
h/o history of  
H&H hematocrit and hemoglobin  
H2 histamine 2  
H20 water  
HAART highly active antiretroviral therapy  
HCT, or Hct hematocrit  
HCT hydrocortisone Better to spell out drug name; can be misinterpreted as hydrochlorothiazide per FDA
HCTZ hydrochlorothiazide Better to spell out drug name; can be misinterpreted as hydrocortisone per FDA
HR heart rate  
HS half-strength better to spell out; do not mistake for "bedtime"
hs or HS at bedtime, hours of sleep Do not misinterpret as 'half-strength'
HTN hypertension  
hx history  
IBW ideal body weight  
ID intradermal OR infectious disease Multiple possible meanings; spell out word instead of using "ID"
IJ injection better to spell out 'injection'
IM intramuscular  
IN intranasal  
inf infusion  
inj. injection  
instill. instillation  
IP intraperitoneal  
IR immediate-release  
IU international unit(s) Mistaken as IV (intravenous) or the number 10 (ten); Instead use "International Unit(s)" (per Joint Commission's "Do Not Use" List of Abbreviations)
IUD intrauterine device  
IV intravenous  
IVP intravenous push Could be confused with 'intravenous pyelogram'
IVPB intravenous piggyback  
J joule  
K potassium  
KOH potassium hydroxide  
L or l liter Lowercase letter l may be mistaken as the number 1 (per ISMP). Instead use L (uppercase) for liter.
LA long-acting  
lab laboratory  
lb. pound  
LDL low-density lipoprotein  
LFT liver function tests  
Li lithium  
liq. liquid  
LMP last menstrual period  
lot lotion  
LPN licensed practical nurse  
LR lactated ringer (solution)  
mane in the morning  
mcg or µg microgram Can be misinterpreted to mean "mg" or milligram, better to spell out 'microgram'
MD medical doctor  
MDI metered-dose inhaler  
mEq milliequivalent  
mEq/L milliequivalent per liter  
Mg magnesium  
mg milligram  
MgSO4 magnesium sulfate May be confused with "MSO4" (morphine sulfate), spell out "magnesium sulfate" - Joint Commission's "Do Not Use" List of Abbreviations
mL milliliter Do not use ml as lowercase l may be mistaken for the number 1. Use mL (lowercase m, uppercase L) for milliliter (per ISMP).
mm millimeter  
MM or M million May be mistaken as thousand. Use million.
M or K thousand May be mistaken as million. Use thousand.
mm of Hg millimeters of mercury  
mMol millimole  
MMR measle-mumps-rubella (vaccine)  
mol wt molecular weight  
MR modified-release  
MS morphine sulfate or magnesium sulfate Can mean either morphine sulfate or magnesium sulfate, spell out full drug name - Joint Commission's "Do Not Use" List of Abbreviations
MSO4 morphine sulfate May be confused with "MgSO4"; instead spell out "morphine sulfate" - Joint Commission's "Do Not Use" List of Abbreviations
n or noct. in the night  
N/A not applicable  
N/V, N&V nausea and vomiting  
Na sodium  
NAS intranasal  
NDC National Drug Code  
Ng or ng nanogram May be mistaken as mg or nasogastric. Use nanogram.
NGT nasogastric tube  
NH3 ammonia  
NKA no known allergies  
NKDA no known drug allergies  
noct. maneq. night and morning  
NP nurse practitioner  
NPO, n.p.o. nothing by mouth Preferred by AMA to spell out "nothing by mouth"
NS normal saline  
NSAID nonsteroidal anti-inflammatory drug  
NTE not to exceed  
O2 oxygen  
OC oral contraceptive  
o.d., OD right eye Can also mean "overdose" or "once daily"; better to spell out "right eye"
o.d. once per day Preferred in the UK; Can also mean "overdose" or "right eye"; better to spell out "once per day"
OJ orange juice  
o.s., OS left eye  
OTC over-the-counter  
PA Physician Assistant  
pc after meals  
PRN as needed  
PM evening  
PO orally or by mouth May be better to spell out "by mouth" or "orally" (per AMA)
q every  
q4h every 4 hours  
q6h every 6 hours  
q8h every 8 hours  
q12h every 12 hours  
qam every morning  
qd, QD, q.d., Q.D. every day Can be mistaken as q.i.d. Instead write "daily" (per The Joint Commission "Do Not Use List") or "use daily" per ISMP list
qhs each night at bedtime Can be confused with "qh" (every hour); better to spell out "each night at bedtime"
q.i.d. , QID four times a day  
qod, QOD, q.o.d., or Q.O.D. every other day

May be mistaken as qid or QID (four times daily).

Write "every other day" (per ISMP and The Joint Commission).

RA rheumatoid arthritis  
Rx prescription  
SA sustained action  
SL, s.l. sublingual (under the tongue)  
SC, SQ sq, or sub q subcutaneous or subcutaneously Use SUBQ (all uppercase) or spell out subcutaneous or subcutaneously
SR sustained release  
STD sexually transmitted disease  
supp suppository  
susp suspension  
syr syrup  
T temperature  
tbsp or Tbsp tablespoon Mistaken as teaspoon(s). Use the metric system (e.g., mL).
TID, t.i.d. three times a day  
top. topical  
TR timed-release  
tsp teaspoon Mistaken as tablespoon(s). Use the metric system (e.g., mL).
U or u unit Mistaken as the number "0" (zero), the number "4" (four) or as "cc". Write "unit" instead (per The Joint Commission "Do Not Use" List).
ud, ut, dict, UD as directed  
ung ointment  
UTI urinary tract infection  
WBC white blood cell  
XR extended-release  
mcg, µg microgram µg mcg can be misinterpreted as "mg". Better to spell out "microgram"

See Also


  1. Taber’s Medical Abbreviations. Tabers Online. Accessed July 13, 2021 at
  2. The Joint Commission Fact Sheet. Official “Do Not Use” List. August 2020 Update Accessed July 14, 2021 at
  3. Mahumud A, Phillips J, Holquist C. Stemming drug errors from abbreviations. FDA Safety Page. Drug Topics. July 1, 2002.
  4. FDA. MedWatch: The FDA Safety Information and Adverse Event Reporting Program. Accessed July 14, 2021 at
  5. FDA Consumer Updates. FDA and ISMP Work to Prevent Medication Errors. March 29, 2012. Accessed July 14, 2021 at
  6. FDA. Animal and Veterinary. A Microgram of Prevention is Worth a Milligram of Cure: Preventing Medication Errors in Animals. June 12, 2019. Accessed July 14, 2021 at
  7. ISMP List of Error-Prone Abbreviations, Symbols, and Dose Designations. Institute for Safe Medication Practices (ISMP). 2021. Accessed July 14, 2021 at

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.