For information on medicine used to treat opioid poisoning (overdose), visit our page: Naloxone.

​​​​​​​​​​Naltrexone (ReVia^®) is used to treat people who have serious drinking problems or to help treat addiction to opioid drugs like codeine, oxycodone, and morphine. It may also be used for other things your doctor decides.

You can’t get addicted to naltrexone. You won’t feel high on it, get physically dependent on it, or have withdrawal symptoms when you stop taking it.

Although naltrexone may help treat problem drinking or dependence on opioids, it isn’t a cure and it doesn't work for everyone. It may work best for people who really want to quit drinking or using drugs and use it along with other forms of therapy like counselling or self-help groups.

Naltrexone and Alcohol

Your doctor will decide how much naltrexone is right for you and how often you need to take it. Naltrexone is usually taken every day for 3 months. After that, you and your doctor can decide if you should keep using it.

If you want to quit drinking, taking naltrexone every day will lessen the urge to drink. If you do drink, you’ll find you don’t enjoy it as much so you'll be less likely to keep drinking. Naltrexone won’t make you feel sick to your stomach or throw up if you drink alcohol while taking it.

Naltrexone doesn’t sober you up. The effects of alcohol (e.g., bad judgement, being clumsy) will still happen even if you're taking naltrexone.

Naltrexone and Opioids

Naltrexone blocks the pleasurable and painkilling effects of opioid drugs, which prevents you from feeling high. This can help someone who used to be, but isn’t physically dependent on opioids anymore, and has a strong desire not to take them anymore.

You have to stop taking opioids 7 to 10 days before you start naltrexone. Because naltrexone can harm the liver, blood work to test your liver function is done before you can start taking it.

Although naltrexone blocks the effects of opioids, taking drugs while on it can still cause poisoning (overdose). Don’t try to take more drugs to overcome the naltrexone. It’s also important not to share your naltrexone with people who are dependent on opioids. If they take it, they might have severe withdrawal symptoms like feeling sick, throwing up, sweating, and feeling anxious.

Side Effects

The side effects you’re most likely to feel depend on whether you’re taking naltrexone for alcohol misuse or opioid addiction.

When you take naltrexone for alcohol problems, the most common side effects are nausea and headaches. Less common side effects include feeling dizzy, feeling nervous or anxious, and feeling tired or drowsy.

When you take naltrexone for opioid addiction, the most common side effects are upset stomach, headaches, trouble sleeping, and feeling nervous. Less common side effects include feeling dizzy, no appetite, constipation, being irritable, and feeling down.

Side effects are usually mild and last only a short time while your body gets used to the medicine. Sometimes women experience more stomach side effects than men.

Naltrexone is not recommended for people who:

• have liver or kidney damage
• are going through withdrawal
• are not motivated to reduce or quit drinking
• are using opioids
• are pregnant (unless the benefit is worth the risk)

Check with your pharmacist before taking other medicine with naltrexone. You can take most medicine while you're on naltrexone, including many over-the-counter types of medicine without codeine like acetaminophen (e.g., Tylenol^®), allergy medicine, and ibuprofen (e.g., Advil^®, Motrin^®).

If you're starting naltrexone, tell your doctor what other medicine you take.

If you're going to have surgery, stop taking naltrexone at least 72 hours before.

For more information and to find an addiction services office near you, please call the 24-hour Help Line.