Naltrexone is a medication approved by the Food and Drug Administration (FDA) to treat opioid use disorders.  It is also used to treat alcoholism.  It comes in a pill form or as an injectable. The pill form of naltrexone (ReVia, Depade) can be taken at 50 mg once per day. The injectable extended-release form of the drug (Vivitrol) is administered at 380 mg intramuscular once a month. Naltrexone can be prescribed by any health care provider who is licensed to prescribe medications.

How Naltrexone Works

Naltrexone blocks the euphoric (pleasure producing) and sedative effects of drugs such as heroin, morphine, and codeine. It works differently in the body than buprenorphine and methadone, which activate opioid receptors.  Naltrexone binds and blocks opioid receptors.  If a person relapses and uses a drug such as heroin, naltrexone prevents the drug from working.

Naltrexone for Opioid Use Disorders

Extended-release injectable naltrexone is approved for treatment of people with opioid use disorder. It can be prescribed by any healthcare provider who is licensed to prescribe medications, special training is not required. The oral formulation can be used as well.  It is important that medically managed withdrawal (detoxification) from opioids be completed at least 7 to 10 days before extended-release injectable naltrexone is initiated or resumed. Research has shown that naltrexone decreases reactivity to drug-conditioned cues and decreases craving. There is no abuse and diversion potential with naltrexone.

Side Effects of Naltrexone

Patients who have been treated with naltrexone lose their tolerance to opioids.  If patients treated with naltrexone relapse after a period of abstinence and try to take the same amount of drug they did previously, it is possible that they could have life-threatening consequences, including respiratory arrest and circulatory collapse.

Other side effects may include:

  • Upset stomach or vomiting

  • Diarrhea

  • Headache

  • Nervousness

  • Sleep problems/tiredness

  • Joint or muscle pain


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