It is considered an opioid antagonist; which means when naloxone is administered, it blocks and reverses the effects of opioids. Opioids attach to receptors in the brain. Once naloxone is administered, the medication essentially finds the opioid receptors and kicks the opioid off of the receptor, temporarily preventing it from reattaching. Temporarily is the key word. It is extremely important that the first step when encountering a suspected overdose is to call 911, as naloxone is not a replacement for emergency care.