Side Effects of Vivitrol

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Vivitrol is the brand name for an FDA-approved drug named naltrexone.

How Vivitrol Works

Vivitrol is most often prescribed to treat alcohol and opioid addiction. It is administered in the form of an intramuscular injection—the standard dosage is 380 milligrams injected into the buttocks once a month.

It is part of medication assisted treatment (MAT) programs for substance use disorder that combine medication along with other treatment modalities such as counseling and social support.

Vivitrol helps treat substance use disorders by blocking the effect of alcohol or opioids and reducing cravings and urges to use the substance. Classified as an opioid antagonist, Vivitrol works by binding to opioid receptors in the brain, which helps reduce the euphoric and sedative effects of addictive substances like alcohol and opioids.

Naltrexone may also help treat breast cancer, by reducing the flow of blood to the tumors and blocking the effects of estrogen, a hormone that may contribute to tumor growth. Low-dose naltrexone may also help treat the symptoms of other health conditions such as multiple sclerosis, fibromyalgia, Crohn’s disease, and complex regional pain syndrome.

One of the major advantages of Vivitrol over other medications that treat substance use disorder, such as methadone, is that it is not addictive and therefore does not have any potential for abuse.

However, Vivitrol does have some side effects that you should be aware of. This article discusses the potential side effects of Vivitrol as well as some strategies that can help you use it safely.

Common Side Effects of Vivitrol

These are some of the common side effects of Vivitrol:

  • Dry mouth
  • Headache
  • Drowsiness
  • Dizziness
  • Nausea
  • Vomiting
  • Tiredness 
  • Weakness 
  • Reduced appetite
  • Muscle cramps
  • Joint pain
  • Toothache
  • Anxiety 
  • Difficulty sleeping
  • Cold symptoms
  • Redness, tenderness, bruising, or itching at the injection site

It’s important that you report any side effects you experience to your healthcare provider.

Serious Side Effects of Vivitrol

Vivitrol can also cause some serious side effects, such as allergic reactions, liver damage, pneumonia, and depression. These are some of the symptoms to look out for:

  • Severe reactions at the injection site: Intense pain, swelling, lumps, scabs, blisters, open wounds, or hardened skin at the injection site are a cause for concern.
  • Liver damage: Fatigue, dark urine, yellow corneas (the white parts of your eyes), or stomach pain that lasts more than a few days could indicate liver damage or hepatitis.
  • Allergic reactions: Severe allergic reactions are characterized by skin rashes, chest pain, feeling dizzy or faint, having difficulty breathing, wheezing, and swelling of the eyes, mouth, tongue, or hands.
  • Depression: Persistent feelings of sadness, numbness, hopelessness, lack of interest, irritability, changes in appetite, difficulty sleeping, and thoughts of self-harm or suicide are some of the symptoms of depression.
  • Pneumonia: Fever, sweating, chills, shortness of breath, fatigue, lack of energy, sharp pain while breathing, and cough that produces yellow, green, or bloody mucus are some of the signs of pneumonia.

If you experience any of these symptoms, it’s important to contact your healthcare provider immediately or go to the emergency room for treatment.

Risk of Opioid Overdose

It’s important to note that taking Vivitrol injections can increase your risk of having an accidental opioid overdose in the following ways:

  • Larger quantities consumed: Vivitrol blocks the effects of opioids, such as heroin, codeine, hydrocodone, oxycodone, and morphine. If you try to overcome this blocking effect by taking larger quantities of the opioid, you may be at an increased risk of experiencing injuries, coma, or death.
  • Increased sensitivity to opioids: Once you receive an injection of Vivitrol, its ability to block the effects of opioids fades over time. You may become more sensitive to the effects of opioids, even if you take the same or lesser amount of opioids you used to before, which can cause you to overdose.

These are the symptoms of opioid overdose:

  • Nausea
  • Stomach pain
  • Drowsiness
  • Dizziness
  • Seizure
  • Physical collapse
  • Difficulty breathing
  • Difficulty awakening

If you or a loved one experience any of these symptoms, call 911 or go to the emergency room immediately.

Precautions to Take If You’re on Vivitrol

These are some precautions you should take, if you’re on Vivitrol, to make your treatment more effective and reduce the chances of experiencing side effects:

  • Ensure there are no opioids in your system: Before you start taking Vivitrol, it’s important to ensure there are no opioids in your system, otherwise you will experience withdrawal symptoms such as shaking, sweating, nausea, and vomiting. You need to wait at least seven to 10 days after your last dose of opioids before you start taking Vivitrol injections. 
  • Tell your doctor what medications you’re on: If you’re not sure whether your medications contain opioids, tell your healthcare provider which medications you have taken in the last 10 days so they can determine when you can start taking Vivitrol injections. Your healthcare provider may need to adjust your medication to ensure you’re not taking opioid medication anymore. Even some cough syrups contain opioids.
  • Disclose any drug use: It’s important to inform your healthcare provider about any street drugs, such as heroin, you have taken in the last 10 days. Your healthcare provider may also prescribe certain tests that can determine whether there are any opiates in your system.
  • Avoid drugs and alcohol: Avoid using substances like opioids, alcohol, drugs, or tranquilizers while you’re on Vivitrol.
  • Get the injections regularly: Avoid missing doses as that can increase your chances of relapse.

Overall, Vivitrol is considered to be a safe and effective medication when used as prescribed. However, if you experience any side effects, it’s important to report them to your healthcare provider and seek emergency treatment immediately if needed.

10 Sources
Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Substance Abuse and Mental Health Services Administration. Naltrexone.

  2. National Library of Medicine. Naltrexone injection.

  3. University of Arkansas for Medical Sciences. What is naltrexone?

  4. University of Massachusetts Chan Medical School. Fact sheet: Naltrexone.

  5. Srivastava AB, Gold MS. Naltrexone: A history and future directions. Cerebrum. 2018;2018:cer-13-18.

  6. National Cancer Institute. Naltrexone hydrochloride.

  7. Younger J, Parkitny L, McLain D. The use of low-dose naltrexone (LDN) as a novel anti-inflammatory treatment for chronic pain. Clin Rheumatol. 2014;33(4):451-459. doi:10.1007/s10067-014-2517-2

  8. Cleveland Clinic. Depression.

  9. American Lung Association. Pneumonia symptoms and diagnosis.

  10. National Alliance on Mental Illness. Naltrexone.

By Sanjana Gupta
Sanjana is a health writer and editor. Her work spans various health-related topics, including mental health, fitness, nutrition, and wellness.