What does "prn" mean in a prescription context?

In a prescription context, "prn" is an abbreviation derived from the Latin phrase "pro re nata," which translates to "as needed." This term is commonly used in medical prescriptions to indicate that a medication should be taken only when necessary rather than on a scheduled basis. For instance, a patient might be instructed to take a pain reliever "prn" if they experience pain, meaning they are not required to take it at regular intervals but can take it as they feel it is needed. This approach allows for more personalized and responsive treatment based on the patient's condition at any given time.

The other options refer to specific dosing schedules: "twice daily" indicates a fixed frequency of administration, "at bedtime" specifies a single daily dose in the evening, and "every meal" suggests medication should be taken with meals. However, none of these options convey the flexible nature of "prn," which underscores its meaning of taking medication as required rather than following a rigid timetable.