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.

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Further information

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

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