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Naltrexone

Brand names: Vivitrol (monthly shot), Revia

Naltrexone treats alcohol use disorder and helps prevent relapse in opioid use disorder by blocking opioid effects and lowering cravings.

Brand namesVivitrol (monthly shot), Revia
Type of medicineOpioid blocker (addiction treatment)
Prescription?Prescription
ImportantThis page is general information, not a prescription. Don't start, stop, or change a medicine without talking to your provider or pharmacist.

Overview

It's not habit-forming. It comes as a daily pill or a monthly shot.

What it's used for

  • Alcohol use disorder
  • Preventing relapse to opioids after detox

How to take it

  • You must be opioid-free for about 7 to 10 days before starting, or it can cause sudden severe withdrawal.
  • Carry a card saying you take naltrexone in case of an emergency.
  • It works best with counseling and support.

Your dose depends on your health and other medicines. Always follow your prescription label, and ask your pharmacist if anything is unclear.

Side effects

Common side effects

  • Nausea
  • Headache
  • Dizziness
  • Tiredness
  • Pain or a lump at the shot site
Call 911Overdose after stopping or trying to overpower the block with opioids. Your tolerance is lower, so a smaller amount can be deadly.
Call your provider todayYellow skin or eyes, dark urine, or upper right belly pain
Call your provider todaySevere pain, hardness, blisters, or a dark scab at the shot site
Call 911Thoughts of suicide or harming yourself. Call or text 988 any time.

Warnings

  • Opioid pain medicines won't work while you're on it; tell every provider.
  • Keep naloxone (Narcan) at home and show family where it is. It can reverse an opioid overdose.

Other medicines, foods, and alcohol

  • It blocks opioid pain medicines, cough medicines with opioids, and some anti-diarrhea medicines.

Tell your provider and pharmacist about every medicine, vitamin, and supplement you take.

Pregnancy and breastfeeding

Talk with your provider.

Missed doses, overdose, and storage

If you miss a dose

Take it as soon as you remember, unless it's almost time for your next dose. Then skip the missed dose. Don't take two doses at once.

If someone takes too much

Call Poison Control at 1-800-222-1222 or get help online at poison.org. Call 911 if the person collapses, has a seizure, has trouble breathing, or can't be woken.

Storing it

Store at room temperature, away from heat and moisture (not in the bathroom), and out of reach of children and pets.

Conditions it's used for

Sources

Last updated 2026-11-13.