PRN (Pro re nata)

PRN (Pro re nata) means "in the circumstances" in Latin. When used in the medical field, PRN means "as the situation arises" or "as needed." It is most often used in reference to the dosage amount of a prescribed medication that does not have a set schedule. Rather, taking the medication is left to the patient or caregiver. PRN does not mean that a daily regimen prescribed by a doctor should ever be exceeded; rather, it simply indicates the medicine may be taken – at the prescribed dosage – if needed.

Typical PRN Medications

Medications labeled PRN are most often not considered maintenance medicines. Rather, PRN is usually associated with medications used to treat specific symptoms. Thus, as the symptoms arise or peak, the patient and/or caregiver can administer a prescribed dosage of the medication as needed. Typical medicines marked as PRN include:

• Analgesics
• Laxatives
• Hydrocodone
• Anti-anxiety medication
• Hypnotics
• And others

Other Uses of the Term PRN

Pro re nata can also be used in conjunction with blood tests. A doctor might write an order for blood work, mark it with PRN, and then give it to his or her patient. The patient can then take the order to a lab to have blood drawn when needed. PRN can also refer to temporary or casual employment – as in, "as needed."