What is a characteristic sign of opioid overdose?

Constricted pupils, also known as miosis, are a hallmark sign of opioid overdose. Opioids have a significant effect on the body's central nervous system, which leads to characteristic physiological responses. When an individual overdoses on opioids, the drug's impact on areas of the brain that control pupil size typically results in pupils that are noticeably smaller than normal. This is a critical indicator that can help differentiate opioid overdose from other types of overdoses or medical emergencies, where pupils may be dilated or have a different response.

In contrast, other signs listed such as rapid heart rate, excessive sweating, or heightened alertness are not associated with opioid overdose. In fact, opioid overdose usually results in decreased heart rate (bradycardia), reduced responsiveness (as opposed to heightened alertness), and may lead to a reduced sweating response due to the slowing of the body's overall functioning. These physiological signs are important for identifying and responding to an opioid overdose effectively.