Naltrexone falls under the category of drugs called opiate antagonists. It has some action on the central nervous system or the brain to prevent the effects of opioids, such as feelings of well-being, euphoria, or pain relief. The medicine has also been found to decrease the desire to take opioids. Since it has some action on the brain, Naltrexone helps people to drink less alcohol or even stop them from drinking alcohol altogether. The drug also decreases the cravings for alcohol when used along with counseling and lifestyle changes.