What Is Naltrexone?

Naltrexone is a medication approved by the Food and Drug Administration (FDA) to treat opioid use disorders and alcohol use disorders. It comes in a pill form or as an injectable. The pill form of naltrexone can be taken up to three days apart. The injectable extended-release form of the drug is administered by a physician once a month. To reduce withdrawal risk, patients are warned to abstain from illegal opioids and opioid medication for a minimum of 7-10 days before starting the injectable form of naltrexone.

Naltrexone for Opioid Dependence

Naltrexone blocks the euphoric 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 in the body that suppress cravings.

While methadone works best for detoxification and as a maintenance treatment, naltrexone is better suited for a person who has already completed the detoxification process and has a short history of opioid misuse. If a person relapses and uses the problem drug, naltrexone prevents the feeling of getting high. People using naltrexone should not use any other opioids or illicit drugs; drink alcohol; or take sedatives, tranquilizers, or other drugs that can slow breathing.

As with all medications used in medication-assisted treatment (MAT), naltrexone is to be prescribed as part of a comprehensive treatment plan that includes counseling and participation in social support programs.

Naltrexone for Alcohol Dependence

When used as a treatment for alcohol dependency, naltrexone blocks the euphoric effects and feelings of intoxication. This allows people with alcohol addiction to reduce their drinking behaviors enough to remain motivated to stay in treatment and avoid relapses. Naltrexone is not addictive nor does it react adversely with alcohol.

Long-term naltrexone therapy extending beyond three months is considered most effective by researchers, and therapy may also be used indefinitely. Learn more about alcohol use disorders.

Side Effects of Naltrexone

People taking naltrexone may experience side effects, but they should not stop taking the medication. Instead, they should consult their doctor or substance misuse treatment practitioner to adjust the dose or change the medication. Some side effects include:

Patients should seek a doctor right away if side effects become more serious, because this may indicate serious liver problems. Serious side effects include: