Medical abbreviations save time in documentation and handoff communication, but they can also cause dangerous errors when misunderstood. This reference covers the abbreviations you'll see most often in clinical nursing — whether you're in nursing school, starting your first floor job, or just need a reliable quick reference.
Important: Some abbreviations on this list (like QD, QOD, and U) appear on The Joint Commission's "Do Not Use" list because they are frequently misread. Where noted, use the written-out form in orders and documentation.
Vital signs and monitoring
BP
Blood Pressure
The force of blood against arterial walls, recorded as systolic/diastolic in mmHg. Normal adult range: less than 120/80 mmHg.
Documentation example: "BP 138/86 left arm, supine."
HR
Heart Rate
Beats per minute (BPM). Normal adult resting range: 60–100 BPM. Below 60 is bradycardia; above 100 is tachycardia.
RR
Respiratory Rate
Breaths per minute. Normal adult: 12–20. Above 20 is tachypnea. Document for one full minute in clinical settings.
SpO₂
Peripheral Oxygen Saturation
Pulse oximetry reading — the percentage of hemoglobin saturated with oxygen. Normal: 95–100%. Below 90% is generally considered hypoxia requiring intervention.
Also seen as "O2 sat" or "sat" in handoff. The "p" distinguishes it from SaO2 (arterial blood gas measurement).
T
Temperature
Documented in Celsius (°C) or Fahrenheit (°F). Fever is typically defined as ≥38.0°C (100.4°F) in adults. Document the route: oral, axillary, rectal, or tympanic.
Orders and timing
PRN
Pro Re Nata (as needed)
From Latin: administer only when a specific condition exists — usually pain, nausea, or another defined trigger. Always document the indication and patient response.
Pronounced: "P-R-N" (spell out the letters).
STAT
Statim (immediately)
From Latin statim: right now, without delay. A STAT order takes priority over all routine tasks. STAT labs, STAT medications, STAT imaging — all mean perform immediately.
NPO
Nil Per Os (nothing by mouth)
The patient must not eat, drink, or take anything orally. Used before surgery, procedures requiring sedation, or when swallowing is unsafe. IV fluids and IV medications continue.
BID
Bis In Die (twice daily)
From Latin: administer the medication twice per day. Typically spaced 12 hours apart (e.g., 0800 and 2000), but your facility's scheduling may vary.
TID
Ter In Die (three times daily)
Administer three times per day. Typically spaced 8 hours apart (e.g., 0800, 1400, 2000).
QID
Quater In Die (four times daily)
Administer four times per day, typically every 6 hours. Do not confuse with QD (once daily) — the similarity has caused medication errors.
Assessment and documentation
SOB
Shortness of Breath
Patient's subjective complaint of difficult or labored breathing. The formal term is dyspnea. Document onset, severity, position, associated symptoms, and O2 saturation.
LOC
Level of Consciousness
Describes alertness and awareness. Document as A&Ox4 (alert and oriented to person, place, time, and event) or use the GCS (Glasgow Coma Scale) for more precise scoring.
I&O
Intake and Output
Fluid balance monitoring. Record all intake (IV, oral, tube feeds) and output (urine, emesis, wound drainage, ostomy). Crucial in renal patients, post-op care, and heart failure management.
Hx
History
Patient's medical history. "PMHx" = past medical history. "FHx" = family history. "SHx" = social history (smoking, alcohol, living situation, occupation).
Dx
Diagnosis
The identified disease or condition. A "differential diagnosis" (DDx) is the list of possible diagnoses being considered before a final Dx is established.
Procedures and interventions
IV
Intravenous
Delivered directly into a vein. IV access (peripheral or central) is required for IV medications, fluids, and blood products. Document site, gauge, date of insertion.
NG
Nasogastric
A tube inserted through the nose and down the esophagus into the stomach. Used for feeding (NGT for tube feeds), decompression, or medication administration when the oral route is unavailable.
Foley
Foley Catheter (indwelling urinary catheter)
A urinary catheter that drains the bladder continuously. Monitor for CAUTI (catheter-associated urinary tract infection). Remove as soon as no longer clinically indicated.
CPR
Cardiopulmonary Resuscitation
Emergency procedure combining chest compressions and rescue breaths to maintain circulation when the heart has stopped. Current AHA guidelines: 30:2 compression-to-ventilation ratio for adults.
DNR / DNI
Do Not Resuscitate / Do Not Intubate
Advance directives specifying the patient does not want CPR (DNR) or mechanical ventilation (DNI) in the event of cardiac or respiratory arrest. Always verify code status at admission and document clearly.
Also written as "AND" (Allow Natural Death) in some facilities — same meaning, considered more patient-centered language.
Why abbreviations matter — and where they go wrong
The Institute for Safe Medication Practices (ISMP) and The Joint Commission maintain lists of abbreviations that should never be used in medication orders because they are so commonly misread. Key examples:
Never use in orders: "U" (unit) — can be misread as 0 or 4; write "unit." "QD" (once daily) — looks like QID (four times daily); write "daily." "MS" — means both morphine sulfate and magnesium sulfate; spell out the drug name.
When in doubt about an abbreviation in an order or note, ask before acting. It is always safer to clarify than to assume.
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