Naltrexone (Revia or Vivitrol) is a medication to treat opioid use disorder (OUD) and alcohol use disorder (AUD).

It is available in pill form or intramuscular injectable. Risk Evaluation and Mitigation Strategy (REMS) is required for Vivitrol (the long-acting injectable formulation) to ensure its benefits outweigh its risks. Naltrexone in pill form is approved for OUD or AUD. Simultaneously, the extended-release injectable formulation is strictly for OUD treatment. The pill form is a daily medication, and the injectable is administered monthly by a licensed doctor.

Naltrexone is most effective as a comprehensive treatment plan, including counseling and other behavioral health therapies. Moreover, a successful recovery must provide patients with a whole-person approach. Naltrexone is recommended for patients older than 18 years of age.

How Does Naltrexone Work and Is It Addictive?

First and foremost, although Naltrexone is part of the Medically Assisted Treatment (MAT) group, it is essential to know that this medication is not an opioid, not addictive, and does not cause withdrawal symptoms. Naltrexone binds and blocks the receptor sites, eliminating the euphoric and sedative effects of opioids such as heroin, fentanyl, and oxycodone. It is also a great option to reduce or suppress opioid cravings. However, unlike other MAT drugs, there is no abuse potential with Naltrexone.


Patients should notify their prescribing doctor about all medications they are currently taking before starting Naltrexone therapy. Furthermore, to reduce the risk of withdrawal symptoms, patients should wait at least a week after their last use of short-acting opioids and two weeks or more for long-acting ones before starting Naltrexone. On the other hand, if they have undergone rapid detox, naltrexone therapy begins immediately. While the oral formulation will block opioid receptors, only Vivitrol (the long-acting injectable formulation) is FDA approved as MAT.

Opioid overdose can happen in several ways. One way is because Naltrexone blocks the effects of opioids. When individuals try overcoming this blocking effect by taking large amounts of opioids, they may experience severe health risks, including overdose or death.

Patients who discontinue Naltrexone use and relapse must be extra careful due to their decreased tolerance to opioids. Taking the same or even lower doses as they have in the past can lead to life-threatening consequences, including overdose.

Learn more about opioid use disorder (OUD)

Naltrexone for Alcohol Use Disorder (AUD)

Patients must not be dependent on alcohol or opioids when starting Naltrexone therapy. Doctors often complete a medically assisted alcohol treatment before administering Naltrexone. This way, they can reduce the chances of substantial side effects such as nausea and vomiting.
Naltrexone reduces cravings, blocks the “high” feeling that makes you want to use alcohol, and also helps minimize the amount of alcohol if there is consumption. Additionally, if the patient decides to stop drinking entirely, taking this drug helps patients maintain their sobriety.

Although this medication does not produce any narcotic-like effects or cause any mental or physical dependence, it also does not prevent impairment when drinking alcohol.

Learn more about alcohol use disorder (AUD)

Before Starting Treatment

Be extra cautious and discuss with your prescribing doctor if the following situations apply to you:

  • Current liver problems
  • Use illegal drugs
  • Suffer from hemophilia or other bleeding issues
  • Have kidney problems or any other health conditions
  • Are you pregnant, planning to become pregnant, or presently breastfeeding
  • Currently taking medications. Prescriptions, non-prescription medicines, vitamins, and herbal supplements.
  • Practitioners need to know if patients are currently taking any medication for pain, cough, colds, or diarrhea, as some of these might contain opioids.
  • Currently in treatment for an OUD or AUD
  • Allergy to Naltrexone or have ever had a side effect to an antagonist drug

Naltrexone Side Effects

Common side effects of Naltrexone may include:

  • nausea
  • vomit
  • sleepiness
  • feeling lethargic
  • headache
  • dizziness
  • stomach issues
  • decreased appetite
  • painful joints
  • muscle cramps
  • cold symptoms
  • trouble sleeping

Serious side effects of Vivitrol (Injectable Naltrexone) may include:

Injection site reactions are possible with Vivitrol, including tissue death, sometimes requiring surgery. Patients should call their prescribing doctors if any of the following issues occur at the injection site:

  • Intense pain
  • Hardening around the injection area
  • Swelling or lumps
  • Blistering
  • Open wound
  • Dark scab

Liver damage and hepatitis are also possible side effects. Patients should immediately call the doctor if they notice dark urine, yellowing of the whites of their eyes, unusual tiredness, or stomach pain lasting more than a few days.

Discontinuation of treatment may occur if other conditions surface during Naltrexone therapy.

Some may include:

  • Serious liver problem
  • Depressed mood
  • Pneumonia
  • Serious allergic reactions
  • Skin rash
  • Swelling of face, eyes, mouth, or tongue
  • Trouble breathing or wheezing
  • Chest pain
  • Feeling dizzy or faint.

These are some, but not all, of the possible side effects. For more information, talk to your prescribing doctor or pharmacist. You can also report all side effects online to MedWatch, the FDA’s reporting medical product safety program for health care professionals, patients, and consumers.




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