Which of the following is the correct expansion of PRN?

• A. Immediately
• B. Daily
• C. At regular intervals
• D. As needed

Answer: (D)

Understanding medication abbreviations used in prescriptions is the idea behind this item. PRN stands for pro re nata, a Latin term meaning “as needed” or “as the situation requires.” It’s used for medications that aren’t scheduled but are taken when symptoms appear, such as a pain reliever used only when pain is present. That’s why “As needed” is the best expansion. The other phrases describe actions that are not conditional on symptoms—immediately implies instant action, daily means every day, and at regular intervals means fixed dosing—none of which capture the on-demand nature of PRN. In practice, using PRN involves documenting the reason, timing, and response to ensure safe and appropriate symptom management.