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Meaning & use

PRN

abbreviation·Advancedmedicaltechnical

Last updated

UK/ˌpiː ɑːr ˈen/
US/ˌpi ɑr ˈɛn/

Meanings

  1. abbreviationfixed phrasemedical

    Written on prescriptions and medical charts to show that a medicine should be taken only when it is needed, not at fixed times.

    Grammar: Said as three letters; it follows the dose: ibuprofen 400 mg PRN.

    Patterns

    • take something PRN

    The nurse checked the chart to see that the painkiller was ordered PRN.

    His prescription reads one tablet every six hours PRN for pain.

    Antiemetics are given PRN, so ask if you feel sick.

  2. abbreviationbefore a nouninformal

    Describing work, shifts or staff who are called in only when needed, rather than on a fixed schedule.

    Grammar: Used before a noun or after be, mostly in healthcare job ads: a PRN nurse.

    Patterns

    • work PRN

    She works PRN at the hospital, covering shifts when the ward is short-staffed.

    The clinic is hiring a PRN therapist.

Common combinations

medication PRN
The doctor ordered pain medication PRN.
PRN order
A PRN order must state the maximum dose per day.
PRN basis
The sedative is given on a PRN basis.
PRN nurse
The agency is looking for a PRN nurse for weekends.
as needed PRN
The label says to use the inhaler as needed, PRN.

Synonyms and how they differ

as needed
As needed is the plain-English version that patients and everyday writing use, while PRN is shorthand used by medical staff.
on demand
On demand is general and not medical, so it would not appear on a prescription.
as required
As required is a slightly more formal, British way of saying as needed.

Opposites

scheduledaround the clock

Word family

pro re nata phrase
the Latin source, meaning for the occasion that arises
p.r.n. abbreviation
a spelling of the same abbreviation with full stops

Commonly confused: PRN or PO? PRN or QD?

PRN vs PO

PO is another prescription shorthand meaning by mouth, not as needed.

PRN vs QD

QD means once daily, the opposite of an as-needed schedule, and is often avoided today because it is easily misread.

Practice

A chart says paracetamol 500 mg PRN. How should the patient take it?

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