Naltrexone (Injection)


Naltrexone (nal-TREX-one)
Helps patients with alcohol problems by keeping the body from wanting alcohol. Also helps narcotic dependents who have stopped taking narcotics to stay drug-free. This medicine is part of a recovery program that includes medical supervision and counseling.

Brand Name(s)

There may be other brand names for this medicine.


When This Medicine Should Not Be Used

You should not receive this medicine if you have had an allergic reaction to naltrexone, polylactide-co-glycolide (PLG), or carboxymethylcellulose. Do not receive this medicine if you are taking or are dependent on medicines that contain opioids or narcotics (such as certain medicines for pain, cough or colds, and diarrhea), heroin, or other illegal (street) drugs. Do not receive this medicine if you have suddenly stopped using opioids (narcotics) and are having withdrawal symptoms. Your doctor will not give you this medicine if you have failed the naloxone challenge test (medical test to check your dependence to opioid medicine) or if you have a positive urine test for opioids. You should not receive this medicine if you have hepatitis or any other liver disease.

How to Use This Medicine

  • Your doctor will prescribe your exact dose and tell you how often it should be given. This medicine is given as a shot into one of your muscles. This medicine is usually given in the buttocks muscle.
  • A nurse or other trained health professional will give you this medicine.
  • Drink plenty of fluids to help avoid constipation.
  • This medicine should come with a Medication Guide. Read and follow these instructions carefully. Ask your doctor or pharmacist if you have any questions. Ask your pharmacist for the Medication Guide if you do not have one. Your doctor might ask you to sign some forms to show that you understand this information.
If a dose is missed:
  • If you miss your scheduled dose, call your doctor to make another appointment as soon as possible.

Drugs and Foods to Avoid

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.
  • Make sure your doctor knows if you are also using medicines that contain opioids or narcotics (such as certain medicines for pain, cough or colds, and diarrhea), heroin, or other illegal (street) drugs.
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine

  • Make sure your doctor knows if you are pregnant or breastfeeding, or if you have kidney problems, liver problems, lung or breathing problems, low platelets in the blood, or bleeding problems such as hemophilia.
  • This medicine may cause pain, itching, burning, redness, swelling, bruising, or a lump under your skin where the shot was given. Call your doctor right away if you have a reaction to the shot that does not go away or that gets worse within 2 weeks after you get the shot.
  • This medicine may cause serious problems with your liver. Call your doctor right away if you start having dark urine, pain in the upper stomach, or yellowing of the eyes or skin while you are using this medicine.
  • This medicine may increase your risk of having a lung disease called eosinophilic pneumonia. Tell your doctor right away if you have shortness of breath, coughing, or wheezing after receiving this medicine.
  • This medicine may cause a serious type of allergic reaction called anaphylaxis. Anaphylaxis 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. 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 blocks the "high" feeling you get from narcotic (opioid) drugs, including heroin. Since naltrexone may make you more sensitive to lower doses of opioids than you have previously used, you should not use heroin or any other narcotic drugs to overcome what the medicine is doing. You could overdose and develop serious problems.
  • 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. Let your doctor know if you or anyone in your family has bipolar disorder (manic-depressive disorder) or has tried to commit suicide.
  • Whenever you need medical care, tell your doctor or other caregiver that you are receiving naltrexone. You may also need to carry a letter to let others know you are using 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 make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.
  • This medicine may cause constipation. This is more common if you use it for a long time. Ask your doctor if you should also use a laxative to prevent and treat constipation.
  • Make sure any doctor or dentist who treats you knows that you are using this medicine. This medicine may affect the results of certain medical tests.

Possible Side Effects While Using This Medicine

Call your doctor right away if you notice any of these side effects:
  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing.
  • Anxiety, depression, or unusual thoughts and behaviors.
  • Chest pain.
  • Fast, pounding, or uneven heartbeat.
  • Fever, chills, cough, runny or stuffy nose, sore throat, and body aches.
  • Lightheadedness, dizziness, drowsiness, or fainting.
  • Nausea, vomiting, loss of appetite, or pain in your upper stomach.
  • Numbness or weakness in your arm or leg, or on one side of your body.
  • Pain in your lower leg (calf).
  • Pain, itching, burning, swelling, or a lump under your skin where the shot was given.
  • Red or black stools.
  • Seizures.
  • Shortness of breath, cold sweats, and bluish-colored skin.
  • Sudden or severe headache, problems with vision, speech, or walking.
  • Trouble sleeping, getting upset easily, having big increase of energy, or starting to act reckless.
  • Yellowing of your skin or the whites of your eyes.
If you notice these less serious side effects, talk with your doctor:
  • Back pain.
  • Change in appetite.
  • Constipation, diarrhea, or stomach pain or upset.
  • Dry mouth.
  • Joint pain, swelling, or stiffness.
  • Mild headache.
  • Muscle pain or cramps.
  • Skin rash, redness, or itching.
  • Tiredness or weakness.

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088
Review Date: 2011-02-04 Reviewed By: Keywords: ,
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