Naloxone

An opioid overdose causes a person's breathing to slow or stop, due to the neuroreceptors for breathing being blocked by opioids. Naloxone works by binding to opioid receptors and reversing/blocking the effects of other opioids and quickly restoring normal respiration. 

Naloxone has no effect on someone who is not overdosing on opioids, and it has been shown not to hurt someone who may be overdosing on a different substance. 

Naloxone has both an intranasal and injectable form. The nasal spray is the most accessible and is easier to use, while the intravenous works faster but requires more preparation and knowledge in giving injections.

Although naloxone works extremely fast and has a high overdose reversal rate, it only works between 30 to 90 minutes (glass window). People who are given naloxone should be observed constantly until emergency care arrives. Some people, after 30-90 minutes, may show signs of an overdose again; administer another dose if this is the case. 

People who are physically dependent on opioids may have withdrawal symptoms within minutes of being given naloxone. Withdrawal symptoms may include headaches, changes in blood pressure, rapid heart rate, sweating, nausea, vomiting, and tremors. Some people will also wake up agitated due to these intense withdrawal symptoms.