The abbreviation "prn" in prescription writing indicates:

The abbreviation "prn," which stands for "pro re nata," is a Latin phrase that translates to "as needed." In the context of prescription writing, it is used to indicate that a medication should be taken only when necessary, rather than on a fixed schedule. This is commonly seen for medications used to manage symptoms such as pain or anxiety, where the patient may only need to take the medication when symptoms arise.

Understanding "prn" is critical for both patients and healthcare providers, as it ensures appropriate medication use and minimizes the risk of overmedication. For example, a physician might prescribe a pain reliever for a patient "prn" for headaches, allowing the patient to take the medication only when they experience a headache rather than following a strict dosing schedule.