Which of the following is an example of a prn order?

A prn order, which stands for "pro re nata," meaning "as needed," specifies medication that can be given at the discretion of the healthcare provider based on the patient's condition or symptoms rather than on a fixed schedule.

The choice indicating Tylenol 500 mg by mouth every 4 to 6 hours for a headache qualifies as a prn order because it provides a range of time between doses, allowing the healthcare provider to administer the medication only when the patient reports having a headache. This flexibility is characteristic of prn orders, showing that the medication is not required on a strict schedule but rather in response to the patient's needs.

In contrast, the other choices specify fixed orders. For example, the order detailing Lomotil requires administration four times a day until diarrhea subsides, which indicates ongoing treatment rather than an as-needed approach. A regular diet implies routine feeding without any conditional stipulations, and the IV antibiotics for 7 days represent a set treatment regimen that must be followed continuously over a specified period. Thus, only the option concerning Tylenol showcases the necessary characteristics of a prn order.