PO Medical Abbreviation
What does PO mean in medical terms?
What is PO?
PO (Per Os) is a Latin medical abbreviation meaning "by mouth," used to indicate that a medication should be taken orally. When a prescription or medical order includes PO, it means the patient swallows the medication rather than receiving it through an injection, IV line, or other route. It is one of the most common route-of-administration abbreviations found on prescriptions, medication orders, and hospital charts.
What PO Stands For and Where It Comes From
PO is an abbreviation for the Latin phrase per os, which translates directly to "through the mouth." Latin has been the foundational language of medicine for centuries, and many abbreviations still in use today trace back to Roman and medieval medical texts. Per means "through" or "by," and os means "mouth" in Latin. Together, they describe the oral route of administration, which remains the most common way medications are given.
While modern medicine has moved away from many Latin terms, PO has endured because it is clear, brief, and universally understood by healthcare professionals across different languages and countries. It appears on handwritten prescriptions, electronic medication orders, nursing notes, and discharge instructions worldwide.
How PO Is Used in Clinical Settings
In a hospital or clinical environment, PO appears as part of a medication order that tells nurses and pharmacists exactly how a drug should be delivered. A typical order might read "metformin 500 mg PO twice daily" or "ibuprofen 400 mg PO every six hours as needed for pain." The abbreviation answers the question of route without ambiguity, which is critical when many drugs can be given through multiple pathways.
PO orders are also tied to a patient's ability to swallow safely. Before a nurse administers an oral medication, they assess whether the patient is awake, alert, and able to swallow without risk of aspiration. Patients who are unconscious, sedated, or have swallowing difficulties due to stroke or surgery cannot receive PO medications safely. In those cases, the prescribing physician switches to an alternative route such as IV (intravenous) or NG (nasogastric tube).
The transition from IV to PO is a significant milestone during a hospital stay. When a patient is switched from intravenous antibiotics to oral antibiotics, for example, it signals that their condition has improved enough to absorb medication through the digestive system. This shift often marks progress toward discharge.
What PO Means for Patients
If your prescription or medication label includes PO, it simply means you take that medication by mouth, either swallowed as a tablet or capsule, dissolved under the tongue, or measured as a liquid. Most patients encounter this abbreviation on printed prescription sheets rather than on the medication bottle itself, where plain-language instructions like "take by mouth" are typically used instead.
Understanding PO becomes particularly important if you are hospitalized. Your care team may tell you that you are "NPO," which means nil per os, or nothing by mouth. This is the opposite of PO and is ordered before surgeries, certain procedures, or when the digestive tract needs to rest. Being NPO means no food, water, or oral medications until your care team clears you. Confusing the two terms in a clinical setting can have serious consequences, so it is always appropriate to ask your nurse to clarify which medications you should still take even while NPO, as some are continued or switched to IV form.
When reviewing your own discharge paperwork or prescription records, seeing PO next to a drug name confirms it is an oral medication. This helps you organize medications correctly and identify if any need to be taken with food or water.
PO Compared to Other Route-of-Administration Abbreviations
PO is one of many route abbreviations used in medicine. Understanding how it compares to others helps patients read their medication records more accurately. IV stands for intravenous, meaning the drug is delivered directly into a vein. IM means intramuscular, given by injection into muscle tissue. SL stands for sublingual, placed under the tongue to dissolve and absorb through the mouth's mucous membranes rather than being swallowed. TOP or topical refers to medications applied to the skin.
The oral route represented by PO is generally preferred when possible because it is safe, non-invasive, cost-effective, and does not require clinical staff to administer. However, not all drugs can be given PO. Some medications are destroyed by stomach acid, absorbed too slowly, or simply not available in oral form. Others, such as certain chemotherapy agents, require IV delivery to reach therapeutic levels quickly. The route chosen by a physician is always based on the drug's properties, the patient's condition, and the urgency of treatment.
One common source of confusion is the difference between PO and SL. Both involve the mouth, but sublingual medications are not swallowed. Nitroglycerin for chest pain, for instance, is typically given SL because it absorbs rapidly through the blood vessels under the tongue. Swallowing it instead would delay the effect significantly. Always follow the specific route instructions on your prescription to ensure the medication works as intended.
Questions About PO
What does PO mean in medical terms?▾
PO is a medical abbreviation for the Latin phrase per os, meaning 'by mouth.' It indicates that a medication should be taken orally, either swallowed as a pill or liquid, rather than given through an injection or IV. It is one of the most frequently used route-of-administration abbreviations in prescriptions and hospital orders.
What does PO stand for?▾
PO stands for per os, a Latin phrase that translates to 'through the mouth.' Latin abbreviations like PO have been used in medicine for centuries and remain standard in clinical documentation and prescriptions globally.
Is PO the same as taking a medication by mouth?▾
Yes. When a medication order or prescription says PO, it means the patient should take the medication orally, by swallowing a tablet, capsule, or liquid. On consumer-facing pharmacy labels, this is usually written out in plain English as 'take by mouth,' but PO means exactly the same thing.
What is the difference between PO and NPO?▾
PO means per os, or by mouth, indicating oral medications or food are permitted. NPO means nil per os, or nothing by mouth, and is ordered when a patient must not eat, drink, or take oral medications, typically before surgery or a procedure. NPO is the opposite of PO, and the two are frequently seen together in hospital settings.
Why would a doctor switch a patient from IV to PO medications?▾
Switching from intravenous to oral medications is a sign of clinical improvement. It means the patient's condition has stabilized enough that their digestive system can absorb the drug effectively. This transition often reduces costs, eliminates the risk of IV line infections, and typically allows the patient to move closer to discharge.
Can all medications be given PO?▾
No. Some medications cannot be taken orally because they are broken down by stomach acid before reaching the bloodstream, absorb too slowly to be effective, or are not manufactured in an oral form. In those cases, physicians use IV, IM, or another route. The route prescribed is always chosen based on the drug's chemistry and the patient's clinical needs.
What is the difference between PO and SL?▾
Both PO and SL involve the mouth, but they work differently. PO medications are swallowed and absorbed through the digestive tract. SL, or sublingual, medications are placed under the tongue and absorbed directly into the bloodstream through the mucous membrane, bypassing digestion for faster action. Nitroglycerin for heart conditions is a common example of an SL medication.
Where will I see PO written on my medical records or prescriptions?▾
PO most commonly appears on printed prescription sheets from a doctor's office, hospital medication administration records, and discharge instructions. It will appear alongside the drug name, dose, and frequency, for example 'amoxicillin 500 mg PO three times daily.' Consumer pharmacy labels typically replace PO with plain-language instructions such as 'take by mouth.'