Which of the following symptoms indicates a potential adverse reaction to medication?

A potential adverse reaction to medication can manifest in a variety of ways, and an unexplained rash is particularly significant in this context. Skin reactions, such as rashes, can indicate an allergic response or other adverse effects to medications. Monitoring for such symptoms is crucial, as they can range from mild to severe and may require immediate medical intervention.

In contrast, improved mood, decreased pain, and increased energy are typically positive outcomes associated with effective medication. These symptoms suggest that the medication is working as intended to alleviate symptoms or enhance the patient's emotional state. However, the presence of an unexplained rash raises concerns about the possibility of a negative reaction that warrants further investigation by a healthcare professional.