Key takeaway
Naltrexone can cause nausea, headache, dizziness, and sleep changes for some people. Serious liver warnings and precipitated withdrawal risk matter before you start. This page is education, not a dosing guide. Call or text (800) 653-9376 to sort medication-assisted options with a real clinic.
Last updated: Wed Oct 07 2026 00:00:00 GMT+0000 (Coordinated Universal Time)
You started naltrexone, or someone handed you a pamphlet, and the side-effect list looks long. Naltrexone is an opioid antagonist used for alcohol use disorder and opioid use disorder. Side effects are common enough that honest counseling belongs in the first visit.
Call 911 for trouble breathing, severe allergic signs, or overdose. Call or text 988 for a crisis.
Common effects
Nausea, headache, dizziness, fatigue, insomnia, and anxiety show up most in the first days or weeks. Food timing, dose schedule, and other medicines matter. This is not a DIY titration chart.
Sibling: naltrexone and Vivitrol.
Serious warnings to respect
Liver injury risk, precipitated opioid withdrawal if opioids are still on board, and the danger of trying to override the blockade with high opioid doses. Clinicians screen for recent opioid use before induction. Emergency care if you suspect precipitated withdrawal.
Oral tablets versus monthly injection
Side-effect profiles overlap. The injection adds site pain, swelling, or nodules for some people. Missed oral doses leave gaps. Missed injection appointments leave gaps too. Ask how the clinic handles both.
Broker filter
A call center that pushes naltrexone as a miracle shot without asking about last opioid use, liver disease, or pregnancy is not doing medicine. Demand a prescribing clinician and lab plan.
Next step
Talk with the prescriber about what you feel. Use FindTreatment.gov or SAMHSA 1-800-662-HELP (4357) for clinics. Call or text (800) 653-9376 when you want help naming medication questions without a sales script.
Call or text (800) 653-9376 for medication-assisted treatment options that include real clinical follow-up.
Additional Resources
Sources cited on this page:
- FDA: Naltrexone labeling information
- NIAAA: Medications for Alcohol Use Disorder
- SAMHSA FindTreatment.gov
- SAMHSA National Helpline
- 988 Suicide & Crisis Lifeline
- NIDA: Principles of Drug Addiction Treatment
Common Questions
What are common naltrexone side effects?
Nausea, headache, dizziness, fatigue, anxiety, and trouble sleeping show up often early on. Many effects ease after the first weeks. Report severe or lasting symptoms to the prescribing clinician.
Can naltrexone damage the liver?
Naltrexone carries liver-related warnings. Clinicians often check liver tests before and during treatment. Do not stack it with heavy drinking or other hepatotoxic drugs without medical advice.
Will naltrexone make me sick if I drink or use opioids?
Naltrexone blocks opioid receptors. Drinking alcohol does not create an Antabuse-style reaction. Using opioids while blocked can be dangerous if people try to override the blockade.
How is this different from low-dose naltrexone (LDN)?
Search traffic for naltrexone side effects often mixes addiction-dose naltrexone with off-label low-dose use. This page covers FDA-approved alcohol and opioid use disorder dosing ranges directed by a clinician.
Should I stop naltrexone on my own if side effects bother me?
Call the prescriber first. Sudden stops without a plan can leave you unprotected if relapse risk is high. See naltrexone and Vivitrol for the treatment overview.