When taken as directed, naltrexone may reduce your cravings for alcohol or opioids. You’ll feel less of a need to take drugs or drink. It may change the way you feel in other ways, if you have side effects, but not everyone has them.
The most common possible side effects include:
- Insomnia
- Anxiety
- Restlessness
- Nausea
- Vomiting
- Headache
- Dizziness
- Joint and muscle pain
- Decreased appetite
In some cases, naltrexone may cause liver damage. This may cause severe stomach pain and tiredness, and you may notice dark urine or yellowing eyes.
Naltrexone should not be used while you are taking opioids. It takes about 7 to 10 days for opioids to clear from your body. If you take naltrexone before opioids are out of your system, it may change the way you feel because you may have withdrawal symptoms. These may include:
- Sweating
- Chills
- Shaking
- Nausea
- Vomiting
If you take naltrexone while you still have alcohol in your system, you may feel nauseous.
How naltrexone works
Naltrexone is used for the treatment of opioid use disorder or alcohol use disorder. This type of treatment is called medication-assisted treatment (MAT).
Opioids act on brain receptors called opioid receptors. When these receptors are activated, they cause the pleasurable symptom called euphoria. Naltrexone blocks these receptors and stops your brain from feeling the “high” or craving an opioid. Opioids include hydrocodone, oxycodone, morphine and heroin.
When used for alcohol use disorder, naltrexone blocks endorphin receptors and keeps alcohol from causing euphoria. Blocking these receptors reduces alcohol cravings.
Using naltrexone along with counseling and behavioral therapy can help people with opioid and alcohol use disorder recover.
Naltrexone comes as a tablet with the brand name ReVia. It also comes as an injection with the brand name Vivitrol. When taken as an injection, there may be reactions at the injection site that include pain, swelling, itching and tenderness.
Other drugs used for opioid use disorder, like methadone, are themselves opioids. Although they are safe when used as prescribed, they can be abused and can become addictive. Naltrexone is not an opioid. There is no abuse potential, and it is not addictive.