Overview of Abbreviations on Prescriptions

Interpreting Your Confusing Medication Prescriptions

Doctor writing perscription
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When your doctor hands you a prescription for a medication, you may think some of it is written in another language—maybe because of its bad handwriting and/or perplexing abbreviations and symbols.

Common Medical Prescription Abbreviations 

Many abbreviations on a prescription pertain to how often a person should take a medication, like before a meal, or the route of administration, like inhaled versus by mouth.

Some examples include:

  • a.c. or ac ( before meals)
  • b.i.d. or bid (twice daily)
  • t.i.d. or tid (three times daily)
  • h.s. or hs (at bedtime)
  • p.c. or pc (after meals)
  • s.o.s. or sos (if necessary)
  • p.r.n. or prn (as needed)
  • "inh" for inhaled (like an asthma rescue inhaler)
  • "po" for by mouth
  • "SC" or "SQ" for subcutaneous (like an insulin injection)

The problem with medical abbreviations is that they can be misread or misunderstood by pharmacists, leading to a medication error, and this can be harmful to a patient.

Let's face it, bad handwriting is common, and a slip of the finger on an electronic prescription is also not far-fetched.

Banned Medical Abbreviations by JCAHO

 To prevent these medical errors, the Joint Commission on Accreditation of Health Organizations (JCAHO) created a "Do Not Use" list of abbreviations in 2003.

According to JCAHO, for the following abbreviations, doctors must write the full word and not the abbreviation on any order or medication-related document that is handwritten (including computer forms where there is free text) or pre-printed forms.

  • "U" or "u" for "Unit"
  • "IU" for  "International Unit"
  • "q.d." or "qd" or "Q.D." or "QD" for daily 
  • "qod" or "q.o.d." or "QOD" or "Q.O.D." for every other day 
  • "MS", "MSO4", or "MgSO4" -- must write out either "morphine sulfate" or "magnesium sulfate"
  • No trailing zeros (e.g. doctors must write out 5mg and not 5.0 mg)
  • Lack of leading zeros (e.g. doctors must write 0.5mg instead of .5mg)

More Examples of Error-Prone Medical Abbreviations and Symbols

In 2005, the Institute of Medical Practices, or ISMP, also created a list of medical abbreviations that can cause errors. This list is much larger that the JCAHO list. A few examples include:

  • "cc" be written as "mL" or "milliliters," as "cc" can be mistaken for "U" for units
  • micrograms should be written as "micrograms" or "mcg" and not "μg"
  • avoiding the symbol "@," as this can be confused for a "2." 
  • avoiding "SC" or "SQ," as "SC" can be mistaken for "SL" (sublingual) and "SQ" as " 5 every"—instead, doctors should write out "subcut" or "subcutaneous"

Bottom Line

In good practice, your doctor should write out medical instructions fully on a prescription, including the medication name, frequency of intake, and route of administration—like Ciprofloxacin 250mg by mouth once daily. This ensures clear communication to the pharmacist and/or nurse and optimizes safety for you as a patient.

 Of course, if you suspect an error on your prescription please notify your doctor and pharmacist right away—even with the new abbreviation guidelines, errors do occur. Trust your gut and your keen eye. 



Glassman P. Making Health Care Safer II: An Updated Critical Analysis of the Evidence for Patient Safety Practices. Chapter 5. The Joint Commission's “Do Not Use” List: Brief Review (NEW). Rockville: Evidence Reports/Technology Assessments, No. 211, 2013. 

Kuhn, I.F. Abbreviations and acronyms in healthcare: when shorter isn't sweeter. Pediatric Nursing. 2007 Sep-Oct;33(5):392-8. 

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