Abbreviations for route of administration
Route describes how a medicine enters or is applied to the body. It is separate from the drug name and from the dosage form: a tablet is a form, while oral is a route.
| Short form | Meaning | What it tells you |
|---|---|---|
| PO | By mouth; orally | The route is oral. |
| SL | Sublingual | The medicine is placed under the tongue. |
| IV | Intravenous | The medicine is given into a vein. |
| IM | Intramuscular | The medicine is given into a muscle. |
| PR | Rectally | The route is rectal. |
Abbreviations for frequency and timing
A frequency states how often; a timing instruction can connect use to a meal or another event. These examples explain notation a learner may encounter, not a preferred way to write new directions.
| Short form | Meaning | Important distinction |
|---|---|---|
| BID / b.i.d. | Twice daily | Does not by itself say every 12 hours. |
| TID / t.i.d. | Three times daily | Does not by itself say every 8 hours. |
| QID / q.i.d. | Four times daily | Different from an every-6-hours instruction. |
| q6h | Every 6 hours | Specifies an interval between doses. |
| PRN / p.r.n. | As needed | Does not provide a reason, interval, or maximum on its own. |
| AC / a.c. | Before meals | Describes timing relative to food. |
| PC / p.c. | After meals | Describes timing relative to food. |
| stat | Immediately | Describes timing, not a recurring frequency. |
Abbreviations for forms and quantities
Do not treat every short word as a direction. Some identify a dosage form or a unit instead.
| Short form | Meaning |
|---|---|
| tab | Tablet |
| cap | Capsule |
| susp | Suspension |
| soln | Solution |
| gtt | Drop or drops |
| mg | Milligram |
| mL | Milliliter |
Reading a line of shorthand
For an invented study example, “1 tab PO BID” separates into three parts: one tablet, by mouth, twice daily. The translation still needs the drug name and strength from elsewhere in the prescription. It does not authorize adding an interval that was never specified.
“1 cap PO q6h PRN” means one capsule by mouth every six hours as needed. It still does not tell you what symptom the as-needed instruction refers to. A learner should notice that missing context rather than filling it in from memory.
In both examples, reading the words and judging whether a prescription is complete are different tasks. If real directions are unclear, they need clarification; a guessed expansion is not a substitute.
Abbreviations to recognize but avoid using
Some familiar shortcuts are associated with medication errors. Learn them so you can recognize the problem, then use clear words in their place.
| Error-prone notation | Intended meaning | Clearer wording |
|---|---|---|
| QD / q.d. | Daily | Write “daily.” |
| QOD / q.o.d. | Every other day | Write “every other day.” |
| U / u | Unit | Write “unit.” |
| IU | International unit | Write “international unit.” |
Why context matters more than a memorized list
Abbreviations vary across countries, specialties, and local systems. The same letters can have more than one meaning. A list is useful for learning common conventions, but it cannot settle an ambiguous real instruction.
Keep medication-name abbreviations separate from direction abbreviations. HCTZ stands for hydrochlorothiazide, an ingredient; BID describes frequency. Likewise, ER describes a release formulation rather than a route or a drug class. Recognizing what kind of information a term supplies is often more useful than memorizing the expansion alone.