Description and Brand Names

Drug information provided by: Merative, Micromedex®

US Brand Name

  1. Vivitrol


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.

This product is available in the following dosage forms:

  • Powder for Suspension, Extended Release

Before Using

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:


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.


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.


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


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.

Drug Interactions

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.

  • Alfentanil
  • Alphaprodine
  • Anileridine
  • Benzhydrocodone
  • Buprenorphine
  • Butorphanol
  • Codeine
  • Diacetylmorphine
  • Difenoxin
  • Dihydrocodeine
  • Diphenoxylate
  • Ethylmorphine
  • Fentanyl
  • Hydrocodone
  • Hydromorphone
  • Ketobemidone
  • Levorphanol
  • Meperidine
  • Methadone
  • Morphine
  • Morphine Sulfate Liposome
  • Nalbuphine
  • Nicomorphine
  • Opium
  • Opium Alkaloids
  • Oxycodone
  • Oxymorphone
  • Papaveretum
  • Paregoric
  • Piritramide
  • Propoxyphene
  • Remifentanil
  • Sufentanil
  • Tapentadol
  • Tilidine
  • Tramadol

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.

  • Naldemedine
  • Naloxegol
  • Venlafaxine

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.

  • Yohimbine

Other Interactions

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:

  • Allergy to polylactide-co-glycolide (PLG) or carboxymethylcellulose, history of or
  • Failed the naloxone challenge test (medical test to check your dependence to opioid medicine) or
  • Opioid withdrawal, acute or
  • Physical drug dependence to opioid medicines or
  • Positive urine test for opioids or
  • Receiving opioid analgesics (eg, morphine)—Should not be used in patients with these conditions.
  • Bleeding problems (eg, hemophilia) or
  • Depression, history of or
  • Kidney disease, moderate to severe or
  • Liver disease or
  • Lung or breathing problems or
  • Thrombocytopenia (low platelets in the blood)—Use with caution. May make these conditions worse.

Proper Use

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.


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

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

  1. Bleeding, blistering, burning, coldness, discoloration of the 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
  2. body aches or pain
  3. chills
  4. congestion
  5. cough
  6. discouragement
  7. dryness or soreness of the throat
  8. ear congestion
  9. fear
  10. feeling sad or empty
  11. fever
  12. headache
  13. hoarseness
  14. irritability
  15. lack of appetite
  16. loss of interest or pleasure
  17. loss of voice
  18. nervousness
  19. rash
  20. runny or stuffy nose
  21. sneezing
  22. sore throat
  23. tender, swollen glands in the neck
  24. trouble breathing
  25. trouble concentrating
  26. trouble sleeping
  27. trouble swallowing
  28. unusual tiredness or weakness
  29. voice changes

Incidence not known

  1. Arm, back, or jaw pain
  2. black, tarry stools
  3. bladder pain
  4. bloating
  5. bloody or cloudy urine
  6. bloody stools
  7. blurred vision
  8. chest pain, discomfort, tightness, or heaviness
  9. chills
  10. confusion
  11. constipation
  12. cough
  13. cough producing mucus
  14. decreased urination
  15. diarrhea
  16. difficult, burning, or painful urination
  17. dilated neck veins
  18. dizziness or lightheadedness
  19. dry mouth
  20. fainting
  21. false or unusual sense of well-being
  22. fast, irregular, pounding, or racing heartbeat or pulse
  23. frequent urge to urinate
  24. general feeling of discomfort or illness
  25. hallucinations or seeing, hearing, or feeling things that are not there
  26. headache, severe and throbbing
  27. holding false beliefs that cannot be changed by fact
  28. hyperventilation
  29. increase in heart rate
  30. increase in white blood cells
  31. indigestion
  32. irregular or rapid breathing
  33. irritability
  34. itching, pain, redness, swelling, tenderness, or warmth on the skin
  35. joint or muscle pain
  36. lower back or side pain
  37. nausea
  38. nervousness
  39. numbness or tingling of the face, hands, or feet
  40. pain or discomfort in the arms, jaw, back, or neck
  41. pain, redness, or swelling in the arm or leg
  42. pounding in the ears
  43. redness and soreness of the eyes
  44. restlessness
  45. seizures
  46. shaking
  47. shivering
  48. skin rash
  49. slow or fast heartbeat
  50. sores in the mouth
  51. stomach cramps or pain
  52. sunken eyes
  53. sweating
  54. swelling of the face, fingers, feet, or lower legs
  55. swollen, painful, or tender lymph glands in the neck, armpit, or groin
  56. thirst
  57. tooth or gum pain
  58. unusual excitement, nervousness, or restlessness
  59. vomiting
  60. vomiting of blood or material that looks like coffee grounds
  61. watery or bloody diarrhea
  62. weight gain
  63. wrinkled skin

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

Symptoms of overdose

  1. Sleepiness or unusual drowsiness

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

  1. Difficulty with moving
  2. muscle stiffness
  3. swelling or redness in the joints

Incidence not known

  1. Bleeding after defecation
  2. bloated or full feeling
  3. change in taste
  4. decreased interest in sexual intercourse
  5. drowsiness
  6. excess air or gas in the stomach or intestines
  7. feeling of warmth
  8. feeling unusually cold
  9. heartburn
  10. inability to have or keep an erection
  11. increased sweating
  12. loss in sexual ability, desire, drive, or performance
  13. loss of taste
  14. night sweats
  15. passing gas
  16. redness of the face, neck, arms, and occasionally, upper chest
  17. relaxed and calm
  18. sleepiness
  19. sudden sweating
  20. uncomfortable swelling around anus
  21. unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness
  22. weight loss

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.