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Naltrexone is a medication used to treat opioid (e.g. heroin, morphine) and alcohol dependenceaddiction. It works by blocking the opioid receptor (a molecule that opioids bind to) to prevent opioid “highs” and any pleasure experienced while drinking alcohol. It also reduces cravings for these substances. Naltrexone is available in daily oral (pill) and monthly injectable forms by prescription only.

Naltrexone is most frequently used to treat addiction and to opioids and alcohol. It is also sometimes used to rapidly reverse the effects of opioid intoxication or overdose. However, naltrexone can cause symptoms of withdrawal in patients who are using opioid drugs. Therefore, treatment is started after the body is free of opioids, as demonstrated by the patient providing a clean urine sample. 

Limited studies on this medication have also shown some promise in the treatment of conditions associated with compulsive behaviors (e.g., compulsive sex, gambling addiction, smoking). Researchers are also studying the potential benefits of Naltrexone in the treatment of other conditions, such as Crohn’s disease, a chronic disorder of the digestive tract.

Common side effects of naltrexone include mild to moderate abdominal pain, anxiety, headache, nausea, vomiting and fatigue. The medication does not cause overdose.

Patients should not take naltrexone if they have any allergies to naltrexone or its derivatives. Naltrexone should not be taken by patients with hepatitis or any other liver disease because of an increased risk for liver damage.

Naltrexone should not be taken with any drugs that contain narcotics. This medication is not recommended for women who are pregnant or may become pregnant, women who are breastfeeding, or children. There have been very few studies of naltrexone in elderly patients. However, the medication seems to be similarly effective and as well-tolerated in older adults as it is in younger patients.