Naltrexone (ReVia and Vivitrol) is an opioid antagonist which is used for opiate and alcohol dependence. It works by blocking the opioid receptors in the brain which produce the high associated with substances, but research suggests it can be used for other compulsive behaviors.
Naltrexone is not Narcan
Naltrexone is not to be confused with naloxone. More commonly known as Narcan, naloxone blocks the effects of opioids within two minutes and is used as an emergency medical intervention to prevent overdose. Naltrexone works slower, with effectiveness occurring after 30 minutes and lasts much longer. It does not work with people who currently use a substance, instead, it is used for maintaining sobriety by reducing the urge to use and then blocking the effects.