Reviewed by the HeyPsych Medical Review Board
Board-certified psychiatrists and mental health professionals
Clinical summary for Naltrexone (Vivitrol, ReVia): Naltrexone is a non-addictive medication used in addiction treatment. It can reduce alcohol cravings and helps prevent opioid relapse by blocking opioid receptors. You MUST be opioid-free before starting or it can trigger sudden withdrawal. Don’t test the “block” with opioids—overdose risk goes up, especially near the end of the monthly injection or after stopping.
People don’t usually describe naltrexone as a “feeling” medication. It’s more like: you notice what doesn’t happen.
Alcohol feels less rewarding
"I could drink, but it just didn’t hit the same."
Naltrexone starts blocking receptors quickly, but the real-life benefit (cravings and behavior) can take time to show up consistently.
In psychiatry/addiction care, naltrexone is used for alcohol use disorder (to reduce cravings and heavy drinking) and opioid use disorder (to block opioid effects and reduce relapse risk after detox). It’s not a sedative and it’s not addictive.
Yes, many clinicians start it while someone is still drinking. You don’t have to be abstinent first for alcohol use disorder. The bigger issue is making sure you’re not using opioids—because opioids plus naltrexone can trigger sudden withdrawal.
Typically at least 7 to 10 days opioid-free (including tramadol). If you were on long-acting opioids like methadone or buprenorphine, some people need up to 14 days. When there’s any doubt, a supervised start and/or naloxone challenge can help confirm you’re truly opioid-free.
You may feel little to nothing because the receptors are blocked. The dangerous part is people trying to override the block by taking larger doses—that can cause overdose and death, especially as the medication wears off or after stopping when tolerance is lower.
It’s not really about “stronger.” Vivitrol is long-acting and removes the daily pill decision, which can be a huge advantage. Oral naltrexone works well when adherence is strong. The best choice is usually the one you can realistically stick with.
Nausea is the classic one, especially early. Headache, dizziness, sleep problems, and anxiety/restlessness can happen too. With Vivitrol, injection-site reactions are common—anything severe, worsening, or associated with fever, drainage, or skin breakdown needs urgent evaluation.
It can. Depression and suicidal thoughts have been reported, including postmarketing reports. If mood gets darker, you feel hopeless, or you have suicidal thoughts, treat it like a real emergency and reach out immediately.
It can raise liver enzymes, usually mildly and sometimes transiently. Rarely, more serious hepatitis-type injury has been reported. That’s why baseline and periodic liver tests are standard, and why clinicians avoid starting it during acute hepatitis or liver failure.
Plan ahead. If opioid pain meds might be needed, oral naltrexone is typically stopped at least 72 hours before elective surgery. With Vivitrol, you generally need about 30 days after the last injection for opioid responsiveness to return. Always tell surgeons, dentists, and ER clinicians you’re on naltrexone.
No taper is required. But stopping changes your risk profile—especially in opioid use disorder—because tolerance drops and overdose risk can rise if relapse occurs. If you stop, you should also have a clear relapse prevention plan and naloxone access if opioids are part of your history.
Sometimes off-label, usually as part of combination treatment in specialty addiction care (often paired with bupropion). It’s not a guaranteed fix, but it may provide modest benefit for some people when combined with therapy and structured support.
This treatment information is for educational purposes only. Treatment decisions should be made in consultation with qualified healthcare professionals based on individual circumstances, symptoms, and medical history. Do not attempt treatment without professional guidance.
This information is for educational purposes. Always consult with a qualified healthcare provider before starting any new treatment.