PO Means “By Mouth” in Medication Instructions
PO is the medical abbreviation for the Latin phrase per os, meaning by mouth or orally. On a prescription, medication order, MAR, or clinical note, PO usually identifies the route of administration: the medicine is to be taken through the mouth.
PO does not tell you the dose, how many times a day to take the medicine, whether to take it with food, or whether a tablet can be crushed. Those instructions must come from the rest of the order or the pharmacy label.
What the abbreviation tells you
Latin medical shorthand meaning “by mouth.” In route terminology, PO corresponds to oral administration.
Safety point: Never reconstruct a missing dose or schedule from “PO” alone. If any medication direction is incomplete or unclear, ask the pharmacist or prescriber before taking it.
What does PO mean in medical terms?
The abbreviation comes from per os. In medication instructions, it describes the oral route of administration. The National Institute on Aging lists po as “by mouth,” and NCI/FDA route terminology lists PO as a synonym for the oral route.
PO is a route instruction, not a complete prescription
The most useful way to read PO is as one field in a medication instruction. It answers “By what route?” The answer is by mouth. Other parts of the instruction answer different questions, such as how much medicine to take, how often to take it, when to take it, and why it is being used.
PO tells the route
PO says the medication is intended for oral administration. It may appear next to a tablet, capsule, liquid, or another medicine formulated for use by mouth.
PO does not tell the frequency
Terms such as once daily, BID, TID, QID, or PRN describe timing or frequency. They are separate from the PO route instruction.
PO does not replace the label
The pharmacy label or clinical order still needs to state the actual dose and any food, timing, swallowing, or preparation instructions that apply.
Why the Latin? PO comes from the established medical phrase per os. In patient-facing language, “by mouth” or “orally” is clearer and means the same route in this context.
How to read PO when it appears with other medication shorthand
Start by separating the instruction into parts. This prevents a common mistake: treating one abbreviation as if it described the whole prescription. PO identifies the route; the rest of the line supplies the quantity, schedule, and other conditions.
Find the dose
Look for the amount or dosage form, such as “1 tablet,” “5 mL,” or a strength in milligrams. PO itself does not contain a dose.
Identify PO as the route
Translate PO to “by mouth.” Do not turn it into a timing instruction.
Read the frequency separately
Frequency may be written in plain language or with another abbreviation. For example, NIH patient guidance lists BID as twice a day, TID as three times a day, QID as four times a day, and PRN as as needed.
Check extra conditions
Food instructions, maximum daily limits, duration, tablet-splitting directions, and other precautions are separate. Do not infer them from PO.
If the directions are incomplete: do not guess. Keep the medicine container or order in front of you and ask the pharmacist, prescriber, nurse, or clinic to explain the exact instruction.
Examples of PO in medication directions
These are fictional decoding examples, not personal dosing instructions. They show how PO works alongside dose and frequency information.
| Example wording | How to read it | What PO contributes |
|---|---|---|
| 1 tablet PO BID | One tablet by mouth twice daily. | PO supplies only “by mouth.” BID supplies the frequency. |
| 5 mL PO PRN | 5 mL by mouth as needed, with the full order needed to know the reason and any maximum frequency. | PO identifies the oral route. |
| 500 mg PO every 8 hours | 500 mg by mouth every 8 hours. | PO does not alter the stated 500 mg dose or 8-hour interval. |
| Medication PO with food | Take the medication by mouth with food, according to the rest of the prescription. | The food instruction is separate from the oral-route instruction. |
Fast decoding rule: PO answers “how does it enter the body?” It does not answer “how much?” or “how often?”
PO vs oral, NPO, and sublingual
| Term | Meaning | Why it is different |
|---|---|---|
| PO | By mouth; from per os. | Medication-route shorthand for oral administration. |
| Oral | Administration to or by way of the mouth. | Plain-language route name corresponding to PO in medication terminology. |
| NPO | Nothing by mouth. | A restriction on oral intake, not an instruction to administer a medicine orally. |
| Sublingual | Administration beneath the tongue. | A distinct route. Do not substitute PO/oral instructions for a sublingual instruction. |
PO and NPO are opposites in practical use
If a chart says NPO, the patient has a “nothing by mouth” instruction. Whether a particular medicine is still allowed must be decided by the care team; do not assume that an existing PO medicine automatically overrides NPO status.
Oral is not the same as every mouth-related route
NCI/FDA terminology defines sublingual administration separately as beneath the tongue. Route wording matters because medicines can be formulated for different sites and absorption patterns.
What does “PO intake” mean?
In clinical notes, PO intake usually refers to what a person is taking in by mouth. Depending on the note, that may refer to food, fluids, medications, or overall oral intake. A PubMed-indexed clinical review uses the phrase “poor PO intake” when discussing reduced food and drink intake.
That is a broader charting use than a medication order. In a prescription line, PO usually functions specifically as the route of administration. In a nutrition or hospital-progress note, “PO intake” may describe oral eating and drinking instead.
Context check: If you see “poor PO intake,” “tolerating PO,” or “increase PO fluids,” read the entire sentence. Those phrases are usually discussing oral intake rather than a drug route alone.
What PO does not tell you about taking a medicine
Not the amount
PO does not tell you whether to take one tablet, half a tablet, 5 mL, 500 mg, or any other quantity.
Not the schedule
PO does not mean once daily, twice daily, every eight hours, at bedtime, or as needed. Frequency must be stated separately.
Not a meal instruction
PO alone does not mean with food, before meals, or after meals. Follow the specific medicine label and pharmacist instructions.
Do not infer “crush” or “chew”
An oral route does not automatically mean a tablet can be crushed, split, opened, or chewed. Those details depend on the specific dosage form and product instructions.
Ask when the shorthand and label differ
If a clinical note uses PO but the pharmacy label or packaging seems to give a different route or instruction, do not choose between them yourself. Ask the pharmacist or prescriber to reconcile the directions.
Authoritative sources used for this PO definition
Its patient medication-safety guidance lists “po” as “by mouth” and separately explains common timing abbreviations such as BID, TID, QID, AC, PC, and PRN. Read the NIH/NIA medication-safety guidance.
The glossary defines PO as per os, Latin for “by mouth.” View the NCBI patient-safety terminology table.
The oral route is coded C38288 in NCI Thesaurus terminology, with PO listed as a synonym and oral administration defined as administration to or by way of the mouth. View the NCI EVS controlled terminology source.
NCIt remains an actively maintained biomedical terminology resource. This page uses its oral-route code only as a terminology identifier, not as a diagnosis or billing code. See current NCI Thesaurus releases.
Editorial scope: This page explains medical shorthand. It does not provide a personal medication dose, replace the pharmacy label, or tell a reader to start, stop, or change a medicine.
PO medical abbreviation FAQs
What does PO stand for in medical terms?
PO stands for per os, a Latin phrase meaning “by mouth.” In medication directions, it identifies the oral route of administration.
Is PO the same as oral?
In medication-route terminology, yes. PO is shorthand for taking a medicine by mouth, and NCI/FDA route terminology lists PO as a synonym associated with the oral route.
What does “take 1 tablet PO” mean?
It means the tablet is to be taken by mouth. That phrase still does not tell you how often to take it unless the frequency is written elsewhere in the prescription or label.
Does PO tell me how many times a day to take medicine?
No. PO describes route, not frequency. Frequency may be written separately in plain language or with terms such as BID, TID, QID, or PRN.
What is the difference between PO and NPO?
PO means by mouth. NPO means nothing by mouth. If a patient is NPO, questions about whether a particular medicine can still be given should be confirmed with the healthcare team.
What does PO intake mean in a hospital chart?
PO intake generally means intake by mouth. In a nutrition or progress note it may refer to food and fluids, while PO in a medication order usually identifies the oral route for a medicine.
Can PO mean something else in a medical record?
Abbreviations can be reused locally, so the surrounding sentence matters. On medication orders and prescription directions, the established PO meaning is per os, or by mouth. If the context is not medication-related, confirm the intended meaning with the healthcare professional who wrote the note.