Before taking naltrexone, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: current or recent use (in the last 7 to 14 days) of any type of opioid drug (such as morphine, methadone, buprenorphine), kidney disease, liver disease.

You should carry or wear medical identification stating that you are taking this drug so that appropriate treatment can be given in a medical emergency.

This drug may make you dizzy. Alcohol or marijuana (cannabis) can make you more dizzy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

After stopping naltrexone treatment, you may be more sensitive to lower doses of opioids, increasing your risk of possibly life-threatening side effects from the opioid (such as decreased breathing, loss of consciousness).

This medication blocks the effects of opiate drugs (including heroin) and similar drugs (opioids). However, large doses of heroin or opioids can overcome this block. Trying to overcome this block is very dangerous and may cause serious injury, loss of consciousness, and death. Make sure you completely understand and accept the risks and benefits of using this medication. Follow your doctor's instructions closely.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

This drug passes into breast milk. Consult your doctor before breastfeeding.