Medical Terms guide

Common Medical Abbreviations

Health care workers use many abbreviations to save time. This guide explains some common ones found in medical records, test results, and prescriptions.

Last updated 2 sources

At a Glance

  • Medical abbreviations are shortened forms of words or phrases used in health records.
  • Many come from Latin, especially those used on prescriptions.
  • The same abbreviation can mean different things in different settings.
  • Some abbreviations are discouraged because they have caused errors.
  • When an abbreviation is unclear, asking the care team or a pharmacist is the safest way to understand it.

What It Is

Abbreviations help clinicians write notes quickly, but they can be confusing to others. They appear in visit summaries, hospital records, lab reports, imaging reports, and prescription labels.

Meanings can vary by specialty, hospital, or country. For example, "MS" might stand for multiple sclerosis, mitral stenosis, or morphine sulfate depending on context. For this reason, safety organizations encourage writing out some terms in full.

This guide covers general meanings only. It is not a way to interpret any specific record; the people who wrote a record are the best source for what they meant.

Common Terminology

BP
Blood pressure.
HR
Heart rate, usually in beats per minute.
Hx
History, as in medical history; PMH means past medical history.
Dx
Diagnosis.
Tx
Treatment (sometimes also used for transplant or transfer, depending on context).
Rx
Prescription.
PRN
As needed (from the Latin "pro re nata").
NPO
Nothing by mouth (from the Latin "nil per os"), often used before surgery or procedures.

Where You May See These Terms

Abbreviations commonly appear in:

  • Visit notes and after-visit summaries from clinics.
  • Hospital records, including admission notes, progress notes, and discharge summaries.
  • Lab reports, such as CBC (complete blood count), BMP (basic metabolic panel), and A1C (hemoglobin A1C).
  • Imaging reports, such as CT (computed tomography) and MRI (magnetic resonance imaging).
  • Prescription labels and pharmacy printouts.
  • Online patient portals and test result summaries.

Key Concepts

More abbreviations, grouped by general area:

  • Vital signs: RR (respiratory rate), T or Temp (temperature), SpO2 or O2 sat (oxygen saturation), BMI (body mass index).
  • Visit and history: CC (chief complaint), HPI (history of present illness), ROS (review of systems), FHx (family history), SHx (social history).
  • Symptoms: SOB (shortness of breath), N/V (nausea and vomiting), HA (headache), CP (chest pain).
  • Conditions: HTN (hypertension), DM or T2DM (diabetes mellitus or type 2 diabetes), CAD (coronary artery disease), COPD (chronic obstructive pulmonary disease), GERD (gastroesophageal reflux disease), UTI (urinary tract infection).
  • Tests: ECG or EKG (electrocardiogram), CXR (chest X-ray), UA (urinalysis), TSH (thyroid-stimulating hormone), LDL and HDL (types of cholesterol).
  • Hospital settings: ED or ER (emergency department), ICU (intensive care unit), IV (intravenous), OR (operating room), f/u (follow-up), WNL (within normal limits).

Examples

Abbreviations often seen on prescriptions and medication lists (general meanings only):

  • PO means by mouth; SL means under the tongue (sublingual); IM means into a muscle (intramuscular); SC, SQ, or subcut means under the skin (subcutaneous).
  • BID means twice a day, TID means three times a day, and QID means four times a day.
  • QD (once a day) and QOD (every other day) are discouraged by safety groups because they are easily misread; writing "daily" or "every other day" is preferred.
  • QHS or HS means at bedtime; AC means before meals; PC means after meals.
  • OTC means over the counter (available without a prescription).
  • Sig is short for the directions part of a prescription.

Tips for Reading

General tips for reading abbreviations:

  • Look at the surrounding words, because context often reveals which meaning is intended.
  • Capitalization and punctuation can matter, but different writers use different styles.
  • Trusted references, such as the MedlinePlus abbreviations list, can help with general meanings.
  • Be cautious with abbreviations that look similar, such as "QD" and "QID".
  • Avoid guessing about anything related to medicines; a pharmacist can explain label wording.

Getting Clarification

When an abbreviation is unclear:

  • Ask the clinician, nurse, or office staff what a specific abbreviation in a record means.
  • Pharmacists can explain abbreviations on prescription labels and medication lists.
  • Patient portals often have a message feature for questions about notes or results.
  • Writing down questions before an appointment can make it easier to get them answered.

Questions to Ask a Healthcare Professional

General questions people often find useful to bring to an appointment:

  • What does this abbreviation mean in this part of the record?
  • Could this abbreviation have more than one meaning here?
  • Can the directions on this medication label be explained in plain words?
  • Is there a glossary available through the patient portal?
  • Who is the best person to contact with questions about notes or results?

Sources

This guide was written in plain language from the following authoritative references.

  1. Abbreviations — MedlinePlus (U.S. National Library of Medicine)
  2. Understanding Medical Words: A Tutorial — MedlinePlus (U.S. National Library of Medicine)

Last updated October 8, 2026. FreeDoc guides are general educational information and are not a substitute for care from a qualified professional.