Naltrexone injection may cause liver damage when given in large doses. It is not likely that naltrexone injection will cause liver damage when given in recommended doses. Tell your doctor if you have or have ever had hepatitis or another liver disease. If you experience any of the following symptoms, call your doctor immediately: excessive tiredness, unusual bleeding or bruising, pain in the upper right part of your stomach that lasts more than a few days, light-colored bowel movements, dark urine, or yellowing of the skin or eyes. Your doctor will probably not give you naltrexone injection if you have liver disease or if you develop symptoms of liver disease during your treatment.

Talk to your doctor about the risks of receiving naltrexone injection.

Your doctor or pharmacist will give you the manufacturer's patient information sheet (Medication Guide) when you begin treatment with naltrexone injection and each time you refill your prescription. Read the information carefully and ask your doctor or pharmacist if you have any questions. You can also visit the Food and Drug Administration (FDA) website (https://www.fda.gov/Drugs/DrugSafety/ucm085729.htm) or the manufacturer's website http://www.vivitrol.com to obtain the Medication Guide.

Naltrexone injection is used along with counseling and social support to help people who have stopped drinking large amounts of alcohol to avoid drinking again. Naltrexone injection is also used along with counseling and social support to help people who have stopped abusing opiate medications or street drugs to avoid abusing the medications or street drugs again. Naltrexone injection should not be used to treat people who are still drinking alcohol, people who are still using opiates or street drugs, or people who have used opiates within the past 10 days. Naltrexone is in a class of medications called opiate antagonists. It works by blocking activity in the limbic system, a part of the brain that is involved in alcohol and opiate dependence.

Naltrexone injection comes as a solution (liquid) to be given by injection into the muscle of the buttocks by a healthcare provider once every 4 weeks.

Naltrexone injection will not prevent withdrawal symptoms that may occur when you stop drinking alcohol after drinking large amounts for a long time or when you stop using opiate medications or street drugs.

This medication may be prescribed for other uses; ask your doctor or pharmacist for more information.

Before receiving naltrexone injection,

• tell your doctor and pharmacist if you are allergic to naltrexone, any other medications, carboxymethylcellulose (an ingredient in artificial tears and some medications), or polylactide-co-glycolide (PLG; an ingredient in some injected medications). Ask your doctor or pharmacist if you don't know if a medication you are allergic to contains carboxymethylcellulose or PLG.
• tell your doctor if you have taken any opiate medications including certain medications for diarrhea, cough, or pain; methadone (Dolophine); or buprenorphine (Buprenex, Subutex, in Suboxone) within the last 7 to 10 days. Ask your doctor if you are not sure if a medication you have taken is an opiate Also tell your doctor if you have used any opiate street drugs such as heroin within the last 7 to 10 days. Your doctor may order certain tests to see if you have recently taken any opiate medications or used street drugs. Your doctor will not give you naltrexone injection if you have recently taken an opiate medication or used street drug.
• do not take any opiate medications or use street drugs during your treatment with naltrexone injection. Naltrexone injection blocks the effects of opiate medications and street drugs. You may not feel the effects of these substances if you take or use them at low or normal doses at most times during your treatment. However, you may be more sensitive to the effects of these substances when it is almost time for you to receive a dose of naltrexone injection or if you miss a dose of naltrexone injection. You may experience an overdose if you take normal doses of opiate medications at these times, or if you take high doses of opiate medications or use street drugs at any time during your treatment with naltrexone. An opiate overdose may cause serious injury, coma (long-lasting unconscious state), or death. If you take or use opiate medications or street drugs during your treatment and you develop any of the following symptoms, call your doctor or seek emergency medical care immediately: difficulty breathing, slow, shallow breathing, faintness, dizziness, or confusion. Be sure that your family knows which symptoms may be serious so they can call the doctor or emergency medical care if you are unable to seek treatment on your own.
• you should know that you may be more sensitive to the effects of opiate medications or street drugs after you finish your treatment with naltrexone injection. After you finish your treatment, tell any doctor who may prescribe medication for you that you were previously treated with naltrexone injection.
• some medications should not be taken with naltrexone injection. Other medications may cause dosing changes or extra monitoring when taken with naltrexone injection. Make sure you have discussed any medications you are currently taking or plan to take before starting naltrexone injection with your doctor and pharmacist. Before starting, stopping, or changing any medications while taking naltrexone injection, please get the advice of your doctor or pharmacist.
• tell your doctor if you have stopped taking opiates or using street drugs and are experiencing withdrawal symptoms such as anxiety, sleeplessness, yawning, fever, sweating, teary eyes, runny nose, goose bumps, shakiness, hot or cold flushes, muscle aches, muscle twitches, restlessness, nausea and vomiting, diarrhea, or stomach cramps, and if you have or have ever had bleeding problems such as hemophilia (a bleeding disorder in which the blood does not clot normally), a low number of platelets in your blood, depression, or kidney disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while receiving naltrexone injection, call your doctor.
• if you need medical treatment or surgery, including dental surgery, tell the doctor or dentist that you are receiving naltrexone injection. Wear or carry medical identification so that healthcare providers who treat you in an emergency will know that you are receiving naltrexone injection.
• you should know that naltrexone injection may make you feel dizzy or drowsy. Do not drive a car or operate machinery or do other dangerous activities until you know how this medication affects you.
• you should know that people who drink large amounts of alcohol or who use street drugs often become depressed and sometimes try to harm or kill themselves. Receiving naltrexone injection does not decrease the risk that you will try to harm yourself. You, your family, or your caregiver should call your doctor right away if you experience symptoms such as feelings of sadness, anxiousness, worthlessness, or helplessness, or thinking about harming or killing yourself or planning or trying to do so. Be sure that your family or caregiver knows which symptoms may be serious so they can call the doctor right away if you are unable to seek treatment on your own.
• you should know that naltrexone injection is only helpful when it is used as part of an addiction treatment program. It is important that you attend all counseling sessions, support group meetings, education programs or other treatments recommended by your doctor.
• talk to your doctor about the risks and benefits of naltrexone injection before you receive your first dose. Naltrexone will remain in your body for about 1 month after you receive the injection and cannot be removed before this time.

Unless your doctor tells you otherwise, continue your normal diet.

If you miss an appointment to receive naltrexone injection, schedule another appointment as soon as possible.

Naltrexone injection may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• nausea
• vomiting
• diarrhea
• stomach pain
• decreased appetite
• dry mouth
• headache
• difficulty falling asleep or staying asleep
• dizziness
• tiredness
• anxiety
• joint pain or stiffness
• muscle cramps
• weakness
• tenderness, redness, bruising, or itching at the injection site

Some side effects can be serious. If you experience any of these symptoms or those listed in the IMPORTANT WARNING section, call your doctor immediately:

• pain, hardness, swelling, lumps, blisters, open wounds, or a dark scab at the injection site
• coughing
• wheezing
• shortness of breath
• hives
• rash
• swelling of the eyes, face, mouth, lips, tongue, or throat
• hoarseness
• difficulty swallowing
• chest pain

Naltrexone injection may cause other side effects. Call your doctor if you have any unusual problems while receiving this medication.

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration's (FDA) MedWatch Adverse Event Reporting program online (https://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can't be awakened, immediately call emergency services at 911.

Symptoms of overdose may include:

• nausea
• stomach pain
• drowsiness
• dizziness

Keep all appointments with your doctor.

Before having any laboratory test, tell your doctor and the laboratory personnel that you are receiving naltrexone injection.

Ask your doctor or pharmacist any questions you have about naltrexone injection.

Keep a written list of all of the prescription and nonprescription (over-the-counter) medicines, vitamins, minerals, and dietary supplements you are taking. Bring this list with you each time you visit a doctor or if you are admitted to the hospital. You should carry the list with you in case of emergencies.

• Vivitrol^®