Generic name: naltrexone (injection) [ nal-TREX-own ]
Brand name: Vivitrol
Dosage form: intramuscular powder for injection, extended release (380 mg)
Drug classes: Antidotes, Drugs used in alcohol dependence

Medically reviewed by Drugs.com on Feb 13, 2024. Written by Cerner Multum.

What is naltrexone?

Naltrexone injection is used to prevent relapse in adults who became dependent on opioids and then stopped using them. Naltrexone can help keep you from feeling a "need" to use the opioid.

Naltrexone injection is also used in adults to treat alcoholism by reducing the urge to drink alcohol. This may help people drink less or stop drinking altogether. You should not be drinking at the time you receive your first naltrexone injection.

Naltrexone may also be used for purposes not listed in this medication guide.

Naltrexone side effects

Get emergency medical help if you have signs of an allergic reaction: hives, difficult breathing, swelling of your face, lips, tongue, or throat.

Using opioid medicine while you are receiving naltrexone could stimulate opioid withdrawal symptoms. Common withdrawal symptoms are craving for opioids, sweating, yawning, fever, stomach pain, vomiting, diarrhea, watery eyes, runny or stuffy nose, tingling, goose bumps, body aches, shaking, muscle twitching, trouble sleeping, and feeling anxious, depressed, fearful, restless or uneasy.

Naltrexone may cause serious side effects. Call your doctor at once if you have:

• weak or shallow breathing;

• cough that does not go away;

• new or worsening cough, wheezing, trouble breathing;

• severe pain, swelling, blistering, skin changes, a dark scab, or a hard lump where the medicine was injected;

• liver problems--stomach pain (upper right side), dark urine, tiredness, jaundice (yellowing of the skin or eyes); or

• symptoms of depression--unusual mood or behavior changes, loss of interest in things you once enjoyed, crying, new sleep problems, thoughts about hurting yourself.

You may feel nauseated the first time you receive a naltrexone injection. You may also have a headache, tiredness, joint and muscle pain, loss of appetite, and vomiting.

Common side effects of naltrexone may include:

• nausea, vomiting, loss of appetite;

• joint pain, muscle cramps;

• headache, dizziness, drowsiness;

• sleep problems (insomnia);

• tooth pain; or

• cold symptoms such as stuffy nose, sneezing, sore throat.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Related/similar drugs

naltrexone, buprenorphine, Suboxone, buprenorphine / naloxone, acamprosate, Subutex, Vivitrol

Warnings

You should not be treated with naltrexone if you are currently using an opioid analgesic, are addicted to opioids or having opioid withdrawal symptoms, or if you have used any opioid medicine such as, methadone, buprenorphine, tramadol, and others opioids within 7 to 14 days.

You should not use naltrexone if you have failed the naloxone challenge test or have tested positive for the urine screen for opioids.

Before taking this medicine

You should not be treated with naltrexone if you are allergic to it, or if:

• you are currently addicted to opioids;

• you are having withdrawal symptoms from opioid addiction;

• you are using any opioid pain medicine (including fentanyl, Vicodin, OxyContin, and many others);

• you have failed the naloxone challenge test or have a positive urine screen for opioids; or

• you have used any opioid medicine such as, methadone, buprenorphine, tramadol, and other opioids within 7 to 14 days.

Also tell your doctor if you have or have ever had:

• bleeding problems such as hemophilia; or

• liver or kidney disease.

It is not known if naltrexone will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant.

Ask a doctor if it is safe to breastfeed while using naltrexone.

How is naltrexone given?

Naltrexone is injected into a muscle. A healthcare provider will give you this injection about once a month (every 4 weeks). Get your naltrexone injection regularly to get the most benefit. Inform your doctor when you received the last dose of naltrexone injection.

You may notice pain, redness, itching, bruising, swelling, or a hard lump where the medicine was injected. Call your doctor if you have this type of reaction, especially if it gets worse or does not clear up within 2 weeks.

Naltrexone is only part of a complete treatment program that may also include additional forms of counseling and/or monitoring. Follow your doctor's instructions very carefully.

Wear a medical alert tag or carry an ID card to let others know you use naltrexone.

After using naltrexone, your body will be more sensitive to opioids. If you use an opioid medicine in the future, you will need to use less than before the naltrexone treatment. Using the same amount you used before could lead to overdose or death.

Naltrexone dosing information

Usual Adult Dose for Alcohol Dependence:

Oral:
Average dose: 50 mg orally once a day
Duration of therapy: 12 weeks

Intramuscular:
380 mg intramuscularly every 4 weeks/once a month

Comments:
-There is no data specifically addressing switching from buprenorphine or methadone to naltrexone, however some patients have reported severe manifestations of precipitated withdrawal when switched from an opioid agonist to opioid antagonist therapy.
-Patients switching from buprenorphine or methadone may be vulnerable to precipitated withdrawal for up to 2 weeks.
-Be prepared to manage withdrawal symptomatically with non-opioid medications.
-To achieve best possible results, implement compliance-enhancing techniques, especially medication compliance

Usual Adult Dose for Opiate Dependence:

Oral:
Initial dose: 25 mg orally once a day
Maintenance dose: 50 mg orally once a day (if no withdrawals on 25 mg/day)

Intramuscular:
380 mg intramuscularly every 4 weeks/once a month

Comments:
-There is no data specifically addressing switching from buprenorphine or methadone to naltrexone, however some patients have reported severe manifestations of precipitated withdrawal when switched from an opioid agonist to opioid antagonist therapy.
-Patients switching from buprenorphine or methadone may be vulnerable to precipitated withdrawal for up to 2 weeks.
-Be prepared to manage withdrawal symptomatically with non-opioid medications.
-This drug is of value only as a part of a comprehensive management plan that includes measures to ensure the patient takes this medication.


Use(s): Blockade of the effects of exogenously administered opioids

What happens if I miss a dose?

Call your doctor for instructions if you miss an appointment for your naltrexone injection.

What happens if I overdose?

In a medical setting an overdose would be treated quickly. Overdose symptoms may include nausea, stomach pain, drowsiness, dizziness, or a reaction where an injection was given (such as severe pain or skin changes).

What should I avoid while receiving naltrexone?

Do not use opioid medication, heroin, or other street drugs while you are receiving naltrexone. Once naltrexone is injected, it cannot be removed from your body. Never try to overcome the effects of naltrexone by taking larger amounts of opioids. Doing so could result in dangerous effects, including coma or death.

Ask your doctor before using any medicine to treat a cold, cough, diarrhea, or pain. These medicines may contain opioids and may not work as well while you are using naltrexone.

naltrexone may cause dizziness or drowsiness and may impair your reactions. Avoid driving or hazardous activity until you know how this medicine will affect you.

What other drugs will affect naltrexone?

Other drugs may affect naltrexone, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell your doctor about all other medicines you use.

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Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Medical Disclaimer

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