Which of the following can indicate a toxic effect of medication?

Life-threatening consequences from an overdose of medication are a critical indicator of a toxic effect. When a medication is taken in excessive amounts, it can overwhelm the body's ability to process and eliminate it, leading to severe and potentially fatal side effects. This can include a wide range of symptoms, depending on the medication involved, and may require immediate medical intervention. Recognizing these serious consequences is crucial because they highlight the importance of adhering to prescribed dosages and monitoring for signs of toxicity.

While other options, such as headaches or nausea, can occur with medications, they do not necessarily signify a toxic effect to the same extent as life-threatening consequences. Options that describe mild or transient symptoms (like feeling energized or nausea that subsides quickly) might indicate side effects but are not inherently indicative of toxicity. Therefore, the presence of life-threatening consequences is a clear and effective marker for a toxic reaction to medication.