Common US Healthcare Acronyms: From STAT to PRN, A Cheat Sheet of Medical and Pharmacy Abbreviations You Need to Know.

Healthcare is full of short forms and Latin phrases. They save time for clinicians but can confuse patients and even new staff. A wrong guess can lead to a wrong dose or missed test. This cheat sheet explains common US medical and pharmacy abbreviations, what they mean, and why they matter. Use it to decode notes, prescriptions, and discharge instructions with confidence.

Timing and frequency (when to take or do something)

Timing abbreviations control dose spacing and monitoring schedules. Errors here cause under- or overdosing, so clarity matters.

• STAT – Do it now. Highest urgency. Used for emergencies (e.g., “Chest X-ray STAT”).
• PRN – As needed. Should list a reason and a frequency cap (e.g., “Acetaminophen 650 mg PO q6h PRN fever”). Without a reason, overuse can happen.
• Q – Every. Often followed by a number and unit: q4h (every 4 hours), q2–4h (every 2 to 4 hours). Keeps blood levels steady.
• QD, QOD – Daily, Every other day. Do not use these; they’re on safety “Do Not Use” lists because they look alike. Write “daily” or “every other day.”
• BID – Twice daily. Aim for 12 hours apart unless told otherwise.
• TID – Three times daily. Space doses through waking hours to avoid sleep disruption.
• QID – Four times daily. Short dosing interval; adherence can be hard.
• HS – At bedtime. Ambiguous (also means “half-strength”). Safer to write “at bedtime.”
• AC – Before meals. Improves absorption for some drugs (e.g., certain diabetes meds).
• PC – After meals. Can reduce stomach upset (e.g., NSAIDs).
• NPO – Nothing by mouth. Prevents aspiration before anesthesia or certain tests.
• PO – By mouth (per os). Clarifies the route for timing plans that include meals.

Routes of administration (how a drug is given)

The route changes how fast and how much of a drug is absorbed, which affects effect and side effects.

• PO – By mouth. Most common route; slower onset than injection.
• IV – Intravenous. Fastest systemic effect. Useful in emergencies or when PO is not possible.
• IVP – IV push (rapid injection). Higher risk if given too fast; rate usually specified.
• IVPB – IV piggyback. Secondary infusion, often antibiotics, over 15–60 minutes.
• IM – Intramuscular. Slower than IV, faster than PO; vaccines often IM.
• SC/SQ – Subcutaneous. “Subcut” preferred to avoid misreading. Used for insulin, heparin.
• SL – Sublingual (under the tongue). Very fast absorption (e.g., nitroglycerin).
• PR – Rectal. Useful if vomiting or NPO (e.g., suppositories).
• IN – Intranasal. Rapid mucosal absorption (e.g., naloxone nasal spray).
• TOP – Topical (on skin). Local effect (creams, ointments, patches).
• GT/NG – Gastrostomy tube/Nasogastric tube. For patients who cannot swallow.
• IT – Intrathecal (into spinal canal). High-risk; must be clearly labeled.

Medication forms and dosing units

Right drug, wrong form or unit can still cause harm. Watch for long-acting vs. immediate-release and unit look-alikes.

• tab, cap – Tablet, capsule. Can be split only if scored and not extended-release.
• susp, soln, elix – Suspension, solution, elixir. Liquids for flexible dosing or children.
• ER/XR/SR/CR/LA – Extended/controlled/long-acting. Do not crush/chew. Designed for steady levels.
• EC/DR – Enteric- or delayed-release. Protects stomach or drug; don’t crush.
• gtt – Drops (ears, eyes). Counted in drops; avoid confusion with “gt.”
• mcg, mg, g – Microgram, milligram, gram. Never use “μg”; it looks like “mg.”
• mL, L – Milliliter, liter. Use mL instead of “cc” to avoid mixing with “u.”
• unit – For insulin, heparin. Spell out “unit”; “U” can be read as a zero.
• tsp, tbsp – Teaspoon, tablespoon. Household spoons vary; use a dosing syringe or cup.

Pharmacy and prescribing shorthand

These appear on prescriptions and pharmacy labels. They shape how you take the medication.

• Rx – Prescription. The order itself.
• SIG – Directions for use. What the patient sees on the label.
• OTC – Over the counter. No prescription needed; still has risks.
• DAW – Dispense as written. No generic substitution allowed.
• Refills (RFL) – How many times the pharmacy may refill without a new Rx.
• QS – Quantity sufficient. Often used with duration (e.g., QS for 30 days).
• NDC – National Drug Code. Identifies the exact product and package size.
• PBM – Pharmacy Benefit Manager. Runs the drug benefit for your plan.
• RxBIN, PCN, Group – Numbers on your insurance card the pharmacy uses to process claims.
• PA – Prior authorization. Insurer approval needed before dispensing; not “physician assistant” in this context.
• QL – Quantity limit. Plan cap on units per time period.
• ST – Step therapy. Insurer requires trying a preferred drug first.

Clinical status and urgent care terms

These show the seriousness of a situation and guide priorities.

• ED/ER – Emergency Department/Room. Entry point for acute care.
• ICU, PICU, NICU – Intensive care for adults, pediatrics, newborns. Higher staffing, continuous monitoring.
• OR, PACU – Operating Room; Post-Anesthesia Care Unit. Immediate post-op recovery happens in PACU.
• L&D – Labor and Delivery. Obstetric care.
• RRT – Rapid Response Team. Called when a patient is deteriorating.
• CPR, BLS, ACLS – Resuscitation levels. Define the skill set and drugs used during a code.
• DNR, DNI – Do Not Resuscitate/Intubate. Respecting code status avoids unwanted, invasive care.
• Full Code – All resuscitation efforts are allowed.

Vitals, labs, and common tests

These abbreviations appear on charts and lab reports. They track stability and guide treatment decisions.

• BP, HR, RR, T, SpO2 – Blood pressure, heart rate, respiratory rate, temperature, oxygen saturation. Core vitals.
• CBC – Complete blood count: WBC (infection), Hgb/Hct (anemia), Plt (clotting).
• BMP/CMP – Basic/Comprehensive metabolic panel: electrolytes (Na, K, Cl, CO2), kidney (BUN, Cr), liver tests (AST, ALT, ALP, Bili in CMP).
• eGFR – Estimated kidney filtration. Guides dose adjustments for many drugs.
• A1C – Average blood sugar over ~3 months. Sets diabetes goals.
• INR, PT, PTT – Clotting tests. Critical for warfarin and bleeding risks.
• TSH – Thyroid-stimulating hormone. Screens for hypo/hyperthyroidism.
• LFTs – Liver function tests (AST, ALT, ALP, bilirubin). Dose-limiting for hepatically cleared drugs.
• UA, C&S – Urinalysis; culture and sensitivity. Targets antibiotics to the right bug.
• EKG/ECG – Heart rhythm tracing. Detects arrhythmias, ischemia.
• CXR – Chest X-ray. Screens for pneumonia, fluid, lines/tubes position.
• CT, MRI, US – Imaging modalities. Each suits different tissues and questions.
• ABG/ VBG – Arterial/venous blood gas. Guides oxygen and ventilation settings.

Documentation and orders

These appear in notes, admission, and discharge paperwork. They shape the care plan and communication.

• H&P – History and Physical. Initial evaluation on admission.
• SOAP – Subjective, Objective, Assessment, Plan. Common progress note format.
• R/O – Rule out. A condition to exclude with testing (e.g., “R/O PE”).
• NKA, NKDA – No known allergies; no known drug allergies. Essential to prevent reactions.
• DC – Discharge or discontinue. Ambiguous; better to write the whole word.
• MAR, eMAR – Medication Administration Record (paper/electronic). The dosing log.
• BCMA – Bar-code medication administration. Reduces wrong-patient and wrong-drug errors.
• TPN – Total parenteral nutrition. IV nutrition; high infection and metabolic risks if mishandled.
• PCA – Patient-controlled analgesia. Patient-activated pain dosing with safety limits.

Care settings and professionals

Knowing who does what helps you direct questions to the right person.

• MD/DO – Physicians. Diagnose, treat, prescribe.
• PA, NP – Advanced practice clinicians. Diagnose, treat, prescribe under state rules.
• RN, LPN – Nurses. Assessment, medication administration, patient education.
• PharmD/RPh – Pharmacists. Medication therapy experts; verify dosing and interactions.
• RT – Respiratory therapist. Manages oxygen, ventilators, breathing treatments.
• PT, OT, SLP – Physical, occupational, speech therapy. Mobility, daily function, swallowing/communication.
• SW, CM – Social work, care management. Discharge planning, resources, coverage.
• SNF, LTACH – Skilled nursing facility; long-term acute care hospital. Post-acute levels of care.

Insurance and health information administration

These drive coverage, billing, and privacy rules.

• HMO, PPO, HDHP – Plan types. Affect network rules and out-of-pocket costs.
• HSA, FSA – Tax-advantaged accounts for medical expenses. Different rules for rollover.
• EOB – Explanation of Benefits. Shows what the insurer paid and what you owe.
• PA – Prior authorization. Approval needed before service or drug; delays if missing.
• HIPAA – Privacy law. Controls who can see your health information.
• EMR/EHR – Electronic medical/health record. Your clinical data system.
• CMS – Centers for Medicare & Medicaid Services. Sets many national coverage and billing policies.
• ICD-10, CPT – Diagnosis and procedure codes. Determine billing and statistics.
• NPI – National Provider Identifier. Unique ID for clinicians and organizations.

Infection control and antimicrobial shorthand

These flags change isolation and antibiotic choices.

• MRSA – Methicillin-resistant Staph aureus. Needs contact precautions; narrows antibiotic choices.
• VRE – Vancomycin-resistant Enterococcus. Similar isolation concerns.
• CDI (C. diff) – Clostridioides difficile infection. Requires soap-and-water handwashing, not just sanitizer.
• C&S – Culture and sensitivity. Guides targeted therapy and avoids resistance.

Abbreviations to avoid (safety risks)

These are on “Do Not Use” lists due to look-alike, sound-alike, or multiple meanings. Write the full term instead.

• U or IU – Use “unit” or “international unit.” “U” can look like a zero or “4.”
• QD, QOD – Write “daily” or “every other day.” They’re easy to confuse.
• MS, MSO4, MgSO4 – Spell out drug names (morphine sulfate, magnesium sulfate). Prevents mix-ups.
• Trailing zero (e.g., 1.0 mg) – Write 1 mg. A trailing zero can turn 1 into 10.
• Lack of leading zero (e.g., .5 mg) – Write 0.5 mg. Prevents a tenfold error.
• D/C – Could mean discharge or discontinue. Write the full word.
• HS, TIW – Ambiguous. Use “at bedtime” or “three times weekly.”
• μg, cc – Use mcg and mL instead. Reduces misreads.

How to decode a prescription or order

Break it into five parts: drug, dose, route, timing, and purpose.

• Example 1: “Amoxicillin 500 mg PO TID x 7 days for sinusitis.”
  – Drug: amoxicillin. Dose: 500 mg. Route: PO. Timing: TID (3 times daily). Duration: 7 days. Purpose: sinusitis.
  Why it matters: Spacing doses 8 hours apart maintains levels and reduces resistance.
• Example 2: “Nitroglycerin 0.4 mg SL q5min PRN chest pain, max 3 doses; call 911 if no relief.”
  – Route SL gives fast absorption. PRN indicates use only with chest pain. Max dose prevents toxicity.
  Why: Clear limits prevent delay in getting emergency care.
• Example 3: “Furosemide 40 mg IVP STAT.”
  – Diuretic given rapidly, right now.
  Why: In acute pulmonary edema, minutes matter for breathing relief.
• Example 4: “Metformin ER 500 mg PO with dinner daily.”
  – ER formulation avoids peaks; taking with food reduces GI upset.

Real-world scenarios (what the acronyms change)

• Discharge meds: If you see “Take 1 tab PO BID PC,” you’ll know it means “twice daily after meals.” If nausea occurs, ask if timing can shift to bigger meals or if a different drug is needed.
• Surgery prep: “NPO after midnight” prevents aspiration during anesthesia. If you need morning meds, ask which are allowed with small sips of water.
• Insulin teaching: “10 units SC before breakfast and dinner” clarifies route (subcutaneous), timing (with meals), and measurement (units spelled out). Verify the syringe type to match units.
• Antibiotic stewardship: UA and C&S results may change “empiric” therapy to “targeted” therapy. Expect the acronym shift in notes and a possible SIG update at the pharmacy.

Tips to prevent mix-ups

• Ask for plain English. Clinicians should translate Latin and acronyms into clear instructions.
• Match the five parts. Every order should name drug, dose, route, timing, and purpose. If one is missing, ask.
• Clarify ER vs. IR. If the label says XR/ER, do not crush. If cost is an issue, ask if an immediate-release alternative is safe.
• Bring the bottle. Show your actual meds at visits so SIG, units, and refills are reconciled.
• Watch for look-alikes. PA (prior auth) vs. PA (physician assistant); DC vs. discontinue; HS vs. half-strength.

Bottom line: Acronyms are useful shortcuts, but they only help when everyone understands them the same way. Knowing the common ones—especially timing (STAT, PRN, BID), routes (PO, IV, SL), and safety pitfalls (QD, U, μg)—keeps care safe, on time, and aligned with your goals. When in doubt, ask for the full words. Clarity is good medicine.

G S Sachin

I am a Registered Pharmacist under the Pharmacy Act, 1948, and the founder of PharmacyFreak.com. I hold a Bachelor of Pharmacy degree from Rungta College of Pharmaceutical Science and Research. With a strong academic foundation and practical knowledge, I am committed to providing accurate, easy-to-understand content to support pharmacy students and professionals. My aim is to make complex pharmaceutical concepts accessible and useful for real-world application.

Mail- Sachin@pharmacyfreak.com