Naloxone can be used when someone is showing signs of opioid overdose. It is a nasal spray, and like Epi-Pens or a first-aid kit, having Naloxone readily available can be very helpful in a crisis. It is not a toxic drug and cannot be used to get high. Naloxone will not cause overdose, so when in doubt, use it. This short video
explains how Naloxone works.