Naltrexone. Potential side effects of Naltrexone (Vivitrol/ Revia) include: nausea, vomiting, abdominal pain, loose stools, constipation, v appetite, insomnia, anxiety, irritability, headache, sedation, ^ energy, v energy, rash & pain of muscles or joints. I have never taken this medication - so I have not experienced side effects.
Not really. Officially, you can find a long list of side effects from Naltrexone and I will not say that there are no side effects. From the practical standpoint, unless you use opioids, no significant side effects are reported. The problem with liver comes only with high doses. Some people are complaining of side effects directly related to the fact that opioid receptors are blocked.