Naltrexone differs from Acamprosate in that it is an opioid antagonist, so if you are using opioids such as codeine, morphine, oxycodone, or heroin, legally or illegally. Naltrexone is probably not for you, and you should mention this to our doctors. It is unclear how Naltrexone works, however the way in which it works is by reducing the pleasurable effects of alcohol, making the consumer less dependent, and easier to go without. Studies show that counselling is a big part of Naltrexone treatment.