Which of the following is a sign of an opioid overdose?

Respiratory depression is a key indicator of opioid overdose and occurs when opioids depress the central nervous system, leading to a significantly reduced rate of breathing. This can result in inadequate oxygen levels in the body, potentially leading to serious complications or death if not addressed promptly. In the context of opioid use, this sign is particularly critical, as maintaining adequate respiratory function is essential for survival.

The other choices reflect conditions or states that are not consistent with an opioid overdose. Increased heart rate may occur in certain situations but is not specifically indicative of overdose; it can be a response to anxiety, pain, or other stimulants. Heightened alertness and loud speech are more characteristic of stimulant drug use or withdrawal states and do not align with the depressant effects caused by opioids. Thus, recognizing respiratory depression as a sign of overdose is vital for prompt recognition and intervention in potentially life-threatening situations.