🔤 Medical Terminology introductory Lesson 3 of 3 4 min read

Common Abbreviations, Symbols & Safe Documentation

Read everyday clinical abbreviations and chart notes, and learn why certain error-prone abbreviations appear on the ISMP and Joint Commission 'Do Not Use' lists.

Reading level

What you'll learn

  • Interpret common clinical abbreviations and symbols used in orders and charting.
  • Explain why certain abbreviations are error-prone and appear on 'Do Not Use' lists.
  • Read a basic chart note and identify its main components.
  • Apply principles of safe, clear documentation to reduce medical errors.

Overview

Clinical documentation is compact by necessity: charts, orders, and hand-off notes use abbreviations and symbols to record a great deal of information quickly. To work safely, you must be able to read these shorthand forms and, just as important, know which ones are dangerous. This lesson covers everyday abbreviations, how to read a basic note, and the safety principle behind the “Do Not Use” list maintained by The Joint Commission and the Institute for Safe Medication Practices (ISMP).

Common Clinical Abbreviations

AbbreviationMeaning
BPBlood pressure
HRHeart rate
RRRespiratory rate
TTemperature
SpO2Oxygen saturation
HxHistory
DxDiagnosis
TxTreatment
RxPrescription / therapy
SxSymptoms
c/oComplains of
WNLWithin normal limits
SOBShortness of breath

Medication and Timing Terms

Many order abbreviations come from Latin. A few are used constantly:

AbbreviationMeaning
PRNAs needed
StatImmediately
NPONothing by mouth
BIDTwice a day
TIDThree times a day
QIDFour times a day
POBy mouth
IVIntravenous
IMIntramuscular
acBefore meals
pcAfter meals
hsAt bedtime

Common Symbols

SymbolMeaning
Increased
Decreased
~Approximately
@At
> / <Greater than / less than
ΔChange

Dangerous, Error-Prone Abbreviations

Some abbreviations are so easily misread that leading safety organizations recommend never using them; they should be written out in full. The core idea of the Joint Commission and ISMP “Do Not Use” list is that ambiguous shorthand causes real harm, especially in medication dosing.

AvoidProblemWrite instead
UMistaken for 0, 4, or cc”unit”
IUMistaken for IV or the number 10”international unit”
QD / QODConfused with each other (daily vs every other day)“daily” / “every other day”
Trailing zero (1.0 mg)The decimal is missed, read as 10 mgWrite “1 mg”
No leading zero (.5 mg)The decimal is missed, read as 5 mgWrite “0.5 mg”
MS, MSO4, MgSO4Morphine and magnesium sulfate confusedWrite the full drug name

The lesson of each row is the same: a small ambiguity can become a tenfold overdose. When in doubt, spell it out.

Reading a Basic Chart Note

Notes are often organized in the SOAP format, which keeps information in a predictable order:

  • S — Subjective: what the patient reports (symptoms, history). Example: “Pt c/o SOB since this morning.”
  • O — Objective: measurable findings and vital signs. Example: “BP 148/92, HR 104, RR 22, SpO2 91% on room air.”
  • A — Assessment: the clinician’s interpretation or diagnosis. Example: “Likely asthma exacerbation.”
  • P — Plan: what will be done next. Example: “Albuterol nebulizer stat; recheck SpO2; admit if no improvement.”

Reading this note, you can see the patient complains of shortness of breath, has an elevated heart and respiratory rate with low oxygen, is thought to be having an asthma flare, and will receive a breathing treatment immediately.

Principles of Safe Documentation

Good charting protects patients. Keep these habits:

  1. Be clear over clever — avoid ambiguous abbreviations; write out anything on a “Do Not Use” list.
  2. Handle decimals carefully — always use a leading zero (0.5), never a trailing zero (not 5.0).
  3. Be timely and factual — record what you observed and did, not opinions about the patient.
  4. Never alter a record — correct an error by drawing a single line through it, initialing, and adding the correction, so the original remains legible.
  5. If it was not documented, it was not done — complete, contemporaneous notes are the legal and clinical record of care.

Why It Matters

Documentation is how the care team communicates across shifts and settings. A misread abbreviation or a misplaced decimal point has caused serious medication errors, which is exactly why the ISMP and Joint Commission created their guidance. Learning to read clinical shorthand and to write clearly is a core safety skill for every EMT, nurse, and clinician, protecting patients long before any procedure begins.

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How the 'Do Not Use' list maps to documented error patterns

The Joint Commission's official Do Not Use list is short and specific because each entry traces to real, reported harm: U/u, IU, Q.D./QOD, trailing zeros and missing leading zeros, and MS/MSO4/MgSO4. ISMP maintains a longer companion list that adds items such as 'micrograms' abbreviated as ug (mistaken for mg, a thousandfold error), '@' (misread as '2'), and apothecary symbols. The common thread is that these are error-reduction rules validated against actual medication events, not stylistic preferences, which is why they are enforced in accredited facilities and audited in chart reviews.

Tall Man lettering for look-alike drug names

A separate ISMP safeguard is Tall Man lettering, which capitalizes the differing middle letters of look-alike, sound-alike drug pairs to force the eye to distinguish them, as in predniSONE versus prednisoLONE, hydrOXYzine versus hydrALAZINE, and DOPamine versus DOBUTamine. This visual technique is built into many electronic health records and pharmacy systems and measurably reduces selection errors from drop-down menus. It pairs with barcode medication administration and the classic 'five rights' (right patient, drug, dose, route, and time) as layered defenses against the mix-ups that plain abbreviations invite.

Key terms

Abbreviation
A shortened form of a word or phrase used to save time in documentation, such as BP for blood pressure.
PRN
From the Latin 'pro re nata', meaning 'as needed'; describes medication given only when required.
Stat
From the Latin 'statim', meaning immediately; an order to be carried out at once.
NPO
From the Latin 'nil per os', meaning nothing by mouth; the patient should not eat or drink.
Do Not Use list
A set of error-prone abbreviations that The Joint Commission and ISMP advise writing out in full to prevent mistakes.
SOAP note
A structured chart format with four parts: Subjective, Objective, Assessment, and Plan.
Vital signs
Core measurements of body function: temperature, pulse, respiratory rate, blood pressure, and oxygen saturation.
BID
From the Latin 'bis in die', meaning twice a day; a dosing frequency.

Check your understanding

5 questions · answers reveal instantly.

  1. 1.What does the abbreviation 'NPO' instruct?
  2. 2.Why is the abbreviation 'U' for 'units' on the 'Do Not Use' list?
  3. 3.In a SOAP note, where does a patient's reported symptom such as 'I have chest pain' belong?
  4. 4.The abbreviation 'stat' means an order should be carried out:
  5. 5.Which practice best supports safe documentation?

Citations & References

Links open publicly available educational and peer-reviewed sources.

  1. Institute for Safe Medication Practices (ISMP).
  2. MedlinePlus, U.S. National Library of Medicine.
  3. Merck Manual (Consumer/Professional).