Which of the following is considered a non-prescribed medication?

Ibuprofen is considered a non-prescribed medication because it is classified as an over-the-counter (OTC) drug. This means that it can be purchased without a doctor's prescription. Non-prescribed medications are typically those that are deemed safe for general use without professional oversight. Ibuprofen is commonly used to relieve pain, reduce inflammation, and lower fever, which makes it accessible to the public without requiring a healthcare provider's guidance.

The other medications listed, such as antibiotics, antidepressants, and prescription painkillers, are all regulated substances that necessitate a prescription from a licensed healthcare professional due to their potential side effects, need for professional monitoring, and specific usage guidelines. The requirement for a prescription indicates that these medications have a higher risk or complexity in their use, differentiating them from over-the-counter options like ibuprofen.