Prescription Abbreviations: What Do They Mean? (2024)

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on Nov 28, 2023.

What are Pharmacy Abbreviations? | Safety | Common Errors | Preventing Errors |Table of Common Prescription Abbreviations

You may wonder what medical abbreviations like "1 tab po bid" mean on your prescription. Healthcare professionals often use abbreviations derived from latin for writing prescriptions or other health notes in medical records.

The prescription abbreviation "1 tab po bid" is interpreted like this:

• the abbreviation "tab" means tablet and comes from the latin tabella
• "po" means by mouth and comes from per os
• "bid" means twice a day, and derives from bis in die.

When written out in plain language, these abbreviations mean "Take one tablet by mouth twice a day."

Luckily you don’t have to worry about interpreting these prescription directions yourself. It’s the pharmacist’s job to put the correct directions on your prescription label. But unclear or poorly written prescription abbreviations is one of the most common and preventable causes of medication errors.

• To address these issues, 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, practitioners and medical record systems have standards to help prevent these common and potentially dangerous medical errors.

Are medical abbreviations safe to use?

Historically, poor penmanship and lack of standardization was the root cause of many written paper prescription errors. Today, most prescriptions are 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.

Even with advances in technology, errors or misunderstanding in electronic prescriptions can occur. 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 medical treatments.

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

Common Abbreviation errors

1. Drug names

Drug names may be frequently abbreviated in medicine. For example, cancer treatment protocols or combination HIV regimens may be written with shortened drug name abbreviations. Examples of possible errors include:

• Acetaminophen (Tylenol), a common over-the-counter pain medicine, is often shortened to "APAP" by healthcare providers, although ISMP states it should be spelled out instead, as not everyone recognizes this abbreviation.
• 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” can be misunderstood to be the shorthand for zidovudine (AZT, an HIV drug) or azathioprine (an immunosuppressant drug).
• "IU", which is intended to mean international units can be misinterpreted to mean IV (intravenous) or the number 10.
• These types of errors may lead to significant patient harm.

2. 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.

3. 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 when required to demonstrate the level of precision of the value being reported, such as for laboratory results, imaging studies that report the size of lesions, or catheter/tube sizes. It may not be used in medication orders or other medication-related documentation."

4. Modified-release dose forms

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.

How to prevent medication errors

Healthcare providers can:

• 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 help lower the risk of confusion due to poor handwriting.
• Medical facilities 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.

In general, to avoid errors in the administration of medications and infusions, spell out the word instead of using an abbreviation. For example, use “international unit” instead of I.U.; “every day” instead of q.d.; “every other day” instead of q.o.d.; and “unit” instead of U.

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 that multiple abbreviations for the same word are avoided. Internal enforcement, regular review and consistency are always the key.

Joint Commission provides a list of mandatory "Do Not Use" abbreviations that must be applied to all orders, preprinted forms, and medication-related documentation (see notes in table below). Medication-related documentation can be either handwritten or electronic. Organizations are required by Joint Commission to follow this list of prohibited abbreviations, acronyms, symbols, and dose designations. However, the Joint Commission does not publish a list of approved abbreviations.

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.
• Read the supplied plain language patient drug information that accompanies your prescription. If you do not have it, ask your doctor or pharmacist for a copy. Your healthcare professional can answer any questions about this information.
• If you receive a prescription with unusual, unexpected or confusing directions, be sure to double check with your doctor and pharmacist.
• FDA encourages all healthcare providers, patients and consumers to report medication errors to the FDA Medwatch Program. This program alerts the FDA to potential problems and allows them to take action to minimize further errors. Timely prevention of medical errors can save a patient’s life.

Table of Common Medical / Prescription Abbreviations

Note: This is not a complete or endorsed list of medical or prescription abbreviations or error-prone abbreviations. The Joint Commission does not publish a list of approved abbreviations. Always speak with your healthcare provider for any questions related to medical abbreviations or terms. Items below marked with ** are found on the Joint Commission's "Do Not Use" List of Abbreviations.

See also

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• Common Drug Side Effects
• Does grapefruit juice interact with my medications?
• Generic Drug FAQs
• How do I remember to take my medications?
• How do I stop my medication safely?
• How to Safely Dispose of Your Old Medications
• Imprint Code FAQs - For Oral Medications
• Injection Types and Sites
• Medical Conversions - How many mL in a teaspoon?
• Pill splitting - Is it safe?
• Top 5 Ways to Avoid Drug Errors
• Top 9 Ways to Prevent a Deadly Drug Interaction
• What are pharmaceutical salt names?
• What are the risks vs. benefits of medications?
• What is the half-life of a drug?
• What is the placebo effect?

Further information

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

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