Medicines and prescriptions
What Does PO Mean on a Prescription?
PO (by mouth) · say it: pee-OHAlso written: p.o., per os, per oral, orally, by mouth
Short answer
PO on a prescription or chart means the medicine is taken by mouth, from the Latin per os.
What it means
PO is short for the Latin per os, which means "by mouth". It tells you the route of a medicine: the way it gets into the body. A tablet, capsule, liquid or chewable medicine that is swallowed is given PO.
You see it on prescriptions, hospital medication charts and discharge letters because the same medicine can come in more than one route. Writing PO makes clear it is the swallowed form and not, for example, an injection (IV or IM), a patch, a suppository or a tablet held under the tongue (SL). It is usually written next to how often the medicine is taken, as in "PO BID" for by mouth twice a day.
PO is easy to confuse with NPO or NBM, which mean nothing by mouth, the instruction not to eat or drink before a procedure. The letter N changes the meaning completely, so it is worth checking which one is written on your own paperwork.
Where you may see it
- Prescriptions and pharmacy labels, next to the dose and how often to take it
- Hospital medication charts and ward drug rounds
- Discharge summaries listing the medicines to continue at home
- Notes that switch a medicine from a drip to tablets ("IV to PO")
📄 How it looks on a report
Paracetamol tablets PO QID PRN
🙅 What it does not mean
- PO does not tell you whether to take the medicine with food or on an empty stomach; that instruction is written separately or given by the pharmacist.
- It does not mean the tablet can be crushed or chewed. Some medicines taken by mouth must be swallowed whole.
- "IV to PO" in hospital notes does not mean treatment has stopped; it usually means the same kind of medicine is now given as tablets.
🎯 Check yourself
Which of these is the right meaning of “PO (by mouth)”?
🗒️ Questions to ask your doctor
🧾 Reports where you will see “PO (by mouth)”
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💊 Medicines whose labels mention “PO (by mouth)”
Plain-English explanations of each medicine, from its official FDA label.
- Acyclovir
An antiviral medicine of the nucleoside analogue type, used against herpesviruses
- Albendazole
an anthelmintic drug, a medicine used to treat infections caused by parasitic worms
- Albuterol
A bronchodilator (a medicine that opens the airways) of the beta-2 adrenergic type. The FDA class is not listed, so this description comes from the label's own wording.
- Alendronate
a bisphosphonate, a medicine that slows the breakdown of bone by blocking cells called osteoclasts
- Allopurinol
a xanthine oxidase inhibitor, a prescription medicine that acts on uric acid
- Alprazolam
a benzodiazepine, a type of central nervous system medicine
- Amitriptyline
An antidepressant of the tricyclic type
- Amlodipine
a calcium channel blocker, a type of medicine that relaxes blood vessels
- Amoxicillin
a penicillin-class antibacterial medicine that works against bacteria
- Amoxicillin and Clavulanate Potassium
A penicillin-class antibacterial combined with a beta-lactamase inhibitor, as the label describes it
🔗 Read more from trusted sources
- “PO (by mouth)” on MedlinePlus ↗
US National Library of Medicine
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General information about a medical word, not advice about your own results. Ask the clinician who ordered the test what it means for you.