What does PRN mean on a prescription?
PRN means as needed. The medication is taken only when a specific symptom is present, rather than on a fixed schedule.
What it stands for
PRN comes from the Latin pro re nata, meaning as the thing is born, or as the situation arises. It tells you that the dose is conditional rather than scheduled.
How it looks on a real label
| Sig code | Label directions |
|---|---|
1 tab po prn nausea | Take 1 tablet by mouth as needed for nausea |
1-2 tabs po q4-6h prn pain | Take 1 to 2 tablets by mouth every 4 to 6 hours as needed for pain |
1 supp pr prn | Insert 1 suppository rectally as needed |
A PRN sig should almost always say what it is for. "As needed" on its own leaves the patient guessing, and a label that does not name the symptom is one a pharmacist will usually query.
PRN is also normally paired with a frequency limit, which is what the Q4-6H is doing in the second example above. Together they say: only when you need it, and no more often than this.
Related codes
| Code | Meaning |
|---|---|
Q4-6H | every 4 to 6 hours |
UT DICT | as directed |
HS | at bedtime |
PO BID | by mouth twice daily |
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This page is educational and is not medical advice. Always follow the directions on your own prescription and ask your pharmacist if anything is unclear.