What does "pro re nata" mean?

according to need (physicians use PRN in writing prescriptions)

What is a synonym for "pro re nata"?

Common synonyms include: as needed, as required, prn.

Pronounced //ˌpɹoʊˌreɪˈnɑ.tɑ//.

/ˌpɹoʊˌreɪˈnɑ.tɑ/ phrase

phrase ·Rare ·Advanced level

Adverb

Phrase

1
Dealing with something that arises unexpectedly or out of due course; for special business.
2
Used on medical charts by doctors to indicate that actions may be taken at the discretion of nursing staff depending on the patient's condition.
3
Used on prescriptions to indicate that the medicines may be taken if and when the patients feel the need.

From the Latin phrase pro (“for”) rē (“thing, matter”) nātā (“born, arisen”): "for what arises".