What are the common side effects of Naltrexone?

Naltrexone is a very safe and well-tolerated medicine. The most common side effects of naltrexone are nausea, diarrhea, headache, dizziness, fatigue, insomnia, and anxiety. If present, most side effects are mild and self-limiting.  Often, it is difficult to determine whether the symptoms are true side effects, or a result the body’s detoxification from chronic alcohol dependence.  Although exquisitely rare, in supra-therapeutic doses naltrexone has been noted to have toxic effects on the liver, so routine blood testing of liver function should be performed prior to treatment and periodically during treatment. Uncommonly, patients may report depression or exacerbation of pre-existing mood disorders.