Naloxone can quickly reverse the effects of opioids. In the brain, it binds to the same sites (receptors) as other opioids such as heroin or fentanyl. Naloxone pushes the other opioid from the receptors, which reverses the overdose for a limited amount of time. An overdose leads to slowed breathing, but naloxone can restore normal breathing within 3 to 5 minutes. If the first dose of Naloxone does not appear to be working, a second dose of naloxone may be needed to help the individual breathe properly.
The effects of naloxone only last for 20 to 90 minutes. After naloxone wears off, the opioid may still be present, and it can bind to its receptors in the brain and cause breathing to slow down again. That means the person is still experiencing an overdose requiring another dose of naloxone. This is why it is important to seek medical help as soon as possible by calling 9-1-1, monitor the person who is experiencing the overdose, and be prepared to give a second dose of naloxone if the overdose symptoms return.
Watch the following video if you want to understand more about how naloxone reverses an overdose: