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Naltrexone (Intramuscular)

Generic name: naltrexone [ nal-TREX-one ]
Brand name: Vivitrol
Drug classes: Antidotes, Drugs used in alcohol dependence

Medically reviewed by Drugs.com. Last updated on Jul 4, 2023.

Uses for naltrexone

Naltrexone injection is used to help narcotic dependents who have stopped taking narcotics to stay drug-free. It is also used to help alcoholics stay alcohol-free. The medicine is not a cure for addiction. It is used as part of an overall program that may include counseling, attending support group meetings, and other treatment recommended by your doctor.

Naltrexone is not a narcotic. It works by blocking the effects of narcotics, especially the "high'' feeling that makes you want to use them. It also may block the "high'' feeling that may make you want to use alcohol. It will not produce any narcotic-like effects or cause mental or physical dependence. It will not prevent you from becoming impaired while drinking alcohol.

Naltrexone will cause withdrawal symptoms in people who are physically dependent on narcotics. Therefore, naltrexone treatment is started after you are no longer dependent on narcotics. The length of time this takes may depend on which narcotic you took, the amount you took, and how long you took it. Before you start using this medicine, be sure to tell your doctor if you think you are still having withdrawal symptoms.

This medicine is to be given only by or under the direct supervision of your doctor.

Before using naltrexone

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For this medicine, the following should be considered:

Allergies

Tell your doctor if you have ever had any unusual or allergic reaction to this medicine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.

Pediatric

Appropriate studies have not been performed on the relationship of age to the effects of naltrexone injection in the pediatric population. Safety and efficacy have not been established.

Geriatric

Appropriate studies performed to date have not demonstrated geriatric-specific problems that would limit the usefulness of naltrexone injection in the elderly.

Breast Feeding

There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.

Interactions with Medicines

Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are receiving this medicine, it is especially important that your healthcare professional know if you are taking any of the medicines listed below. The following interactions have been selected on the basis of their potential significance and are not necessarily all-inclusive.

Using this medicine with any of the following medicines is not recommended. Your doctor may decide not to treat you with this medication or change some of the other medicines you take.

Using this medicine with any of the following medicines is usually not recommended, but may be required in some cases. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Using this medicine with any of the following medicines may cause an increased risk of certain side effects, but using both drugs may be the best treatment for you. If both medicines are prescribed together, your doctor may change the dose or how often you use one or both of the medicines.

Interactions with Food/Tobacco/Alcohol

Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.

Other Medical Problems

The presence of other medical problems may affect the use of this medicine. Make sure you tell your doctor if you have any other medical problems, especially:

Proper use of naltrexone

A nurse or other trained health professional will give you this medicine. This medicine is given as a shot into the buttocks (gluteal) muscle. It is usually given every 4 weeks or once a month.

Naltrexone injection should only be given to alcohol-dependent patients who can abstain from drinking alcohol and does not need an overnight stay in the hospital.

This medicine usually comes with a Medication Guide. Read the information carefully and make sure you understand it before receiving this medicine. If you have any questions, ask your doctor.

If you miss your scheduled dose, call your doctor to make another appointment as soon as possible.

Detailed Naltrexone dosage information

Precautions while using naltrexone

It is very important that your doctor check your progress at regular visits. This will allow your doctor to see if the medicine is working properly and to decide if you should continue to take it. Blood and urine tests may be needed to check for unwanted effects.

This medicine may cause injection site reactions. Check with your doctor right away if you have bleeding, blistering, burning, coldness, discoloration of skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site.

Check with your doctor right away if you have dark urine, general tiredness and weakness, light-colored stools, nausea and vomiting, upper right stomach pain, and yellow eyes and skin. These may be symptoms of serious liver problems.

Check with your doctor right away if you have chest pain, dry cough, fever, general feeling of tiredness or weakness, rapid breathing, skin rash, or trouble breathing. These may be symptoms of a lung problem called eosinophilic pneumonia.

This medicine may cause a serious type of allergic reaction called anaphylaxis, which can be life-threatening and requires immediate medical attention. Call your doctor right away if you have a rash, itching, hoarseness, trouble breathing, trouble swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.

You will need to stop using opioids (narcotics) for at least 7 to 10 days before you can start receiving naltrexone injection. Your doctor may need to do the naloxone challenge test or a urine test for opioids to make sure you are opioid-free.

This medicine may increase thoughts of suicide. Tell your doctor right away if you start to feel more depressed. Also tell your doctor right away if you have thoughts about hurting yourself. Report any unusual thoughts or behaviors that trouble you, especially if they are new or get worse quickly. Make sure your caregiver knows if you feel tired all the time, sleep a lot more or a lot less than usual, feel hopeless or helpless, or if you have trouble sleeping, get upset easily, have a big increase in energy, or start to act reckless. Also tell your doctor if you have sudden or strong feelings, such as feeling nervous, angry, restless, violent, or scared.

Remember that use of naltrexone is only part of your treatment. Be sure that you follow all of your doctor's orders, including seeing your therapist and/or attending support group meetings on a regular basis.

Do not try to overcome the effects of naltrexone injection by taking narcotics. You may be more sensitive to the effects of narcotics than you were before beginning naltrexone treatment. You could overdose and develop serious problems, including coma or death. Symptoms of an opioid overdose include: drowsiness, extreme dizziness or weakness, irregular, fast or slow, or shallow breathing, pale or blue lips, fingernails, or skin, pinpoint pupils, relaxed and calm, slow heartbeat or breathing, seizures, sleepiness, trouble breathing, or cold, clammy skin. Tell your doctor right away if you notice these symptoms. Your doctor may also give naloxone to treat an overdose.

Naltrexone injection also blocks the useful effects of narcotics. Always use a non-narcotic medicine to treat pain, diarrhea, or a cough. If you have any questions about the proper medicine to use, check with your doctor.

Naltrexone injection will not prevent you from becoming impaired when you drink alcohol. Do not take naltrexone in order to drive or perform other activities while under the influence of alcohol.

After naltrexone is injected into your body, it is impossible to remove it.

It is recommended that you carry an identification card stating that you are receiving naltrexone injection. You may also need to carry a letter to let others know you are receiving this medicine in case you have a medical emergency.

You may experience nausea after the first injection of this medicine that should be mild and subside a few days afterwards. You will be less likely to have nausea with your next injections.

This medicine may cause some people to become dizzy, drowsy, or less alert than they are normally. If any of these side effects occur, do not drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert while you are receiving naltrexone injection.

Before you have any medical tests, tell the medical doctor in charge that you are receiving this medicine. The results of some tests may be affected by this medicine.

Side Effects of naltrexone

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur:

More common

Incidence not known

Get emergency help immediately if any of the following symptoms of overdose occur:

Symptoms of overdose

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

Incidence not known

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.

Naltrexone side effects (more detail)

Commonly used brand name(s)

In the U.S.

Available Dosage Forms:

Therapeutic Class: Ethanol Dependency

Pharmacologic Class: Opioid Antagonist

Frequently asked questions

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Further information

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

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