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What Should You Avoid When Taking Naltrexone?

Elena Hill, MD, MPH profile image
Medically Reviewed By Elena Hill, MD, MPH • Updated Aug 11, 2023 • 4 cited sources

Naltrexone is a valid addiction treatment option for alcohol use disorder and sometimes for opioid use disorder, but it does require some understanding of how it works and what other medications to avoid while using it in order to get the best effects from treatment. It should never be taken with opioids in your system as it can cause a precipitated withdrawal. Find out more here. 

What Is Naltrexone Used For?

Naltrexone, which comes as either a pill or injectable, is a medication used to treat opioid use disorder and alcohol use disorder as part of Medication for Addiction Treatment (MAT).[1] Naltrexone is not addictive and not an opioid. In fact, it is an opioid antagonist, meaning it blocks the euphoric and sedative effects of opioids.  

In the case of alcohol use disorder, Naltrexone acts by staying in the body so that, if you do use an opioid, you will not get “high” from that opioid, and will have a much lower likelihood of overdose. In this way Naltrexone prevents the rewards of getting high and also helps keep patients safe from an overdose. 

The way Naltrexone works for alcohol use disorder is less well understood. Most experts think that Naltrexone, as an opioid antagonist, acts on the reward centers of the brain and decreases the cravings/desire for patients to use alcohol over time. In this way it has been shown to decrease the number of days and quantity of drinking in patients with AUD. 

What Are Naltrexone’s Side Effects?

Naltrexone is associated with a few common side effects, including these:[2]

  • Headache
  • Sleepiness
  • Dizziness
  • Nausea
  • Vomiting
  • Decreased appetite
  • Joint and muscle pain
  • Cold symptoms
  • Insomnia
  • Toothaches

More serious and much rarer side effects that you should discuss with your doctor include the following:

  • Liver damage
  • Complications at the injection site
  • Serious allergic reaction (extremely rare)

Most of these common side effects are mild and will often abate once the body gets used to the new medication. If you have any side effects that are persistent, particularly any of the serious side effects, talk immediately with your doctor. 

What to Avoid When Taking Naltrexone

There are a few things you shouldn’t take while taking naltrexone, including:[3]


You should always talk to your doctor before combining any opioid medications with naltrexone. This includes any opioid pain medications such as oxycodone, vicodin, hydromorphone, dilaudid, morphine, methadone, codeine, etc. The reason for this is something called precipitated withdrawal: If you take an opioid and then take Naltrexone too soon afterward, Naltrexone will kick all the opioid off your opioid receptors and cause an acute withdrawal syndrome. While this is never life threatening or dangerous, it can make patients feel awful and incredibly sick, which can even motivate them to return to opioid use and relapse. If you need to take an opioid medication for acute pain, talk to your doctor: they can give you clear instructions about when and how long to hold your Naltrexone and when to restart it.

Other classes of medications other than opioids are usually safe to take with Naltrexone. However, if you are taking a number of medications that affect your liver, you may want to discuss with your doctor. A good rule of thumb is to ask your doctor about any new medications you may need to take and whether they can be taken with Naltrexone. Your doctor can advise you easily about this. 

Illicit Substances

Just like with opioid medications, taking Naltrexone with any illicit substances such as heroin or fentanyl can cause the same problems of precipitated withdrawal as per above.

Some people try to overcome the effects of naltrexone by taking more drugs than usual. This is very dangerous and can potentially cause a life-threatening overdose. If you are using on top of your naltrexone, talk to your doctor. They can help adjust your dose or connect you to other resources to help prevent you from returning to use. 


Naltrexone can partially blunt the effects of alcohol and overall decreases the cravings/desires to drink. There are a lot of misconceptions about drinking while on Naltrexone. First, understand that you CAN drink safely while on Naltrexone. You may not get “drunk” as quickly as you are used to as Naltrexone may dampen the euphoric effects, but you will not cause harm to yourself by doing so. The goal of using Naltrexone therapy is to encourage people to drink less overall, over time. If you do have a drink after taking Naltrexone, you will not experience dangerous health effects. 

Getting Help for an Opioid Use Disorder or Alcohol Use Disorder

If you think you may have an opioid use disorder or alcohol use disorder, there are a variety of evidence-based treatments you can discuss with a medical professional, including the use of naltrexone.[4] If you think Naltrexone might be a good treatment option for you, reach out to your regular medical provider or to us here at Bicycle health for more information.

Medically Reviewed By Elena Hill, MD, MPH

Elena Hill, MD; MPH received her MD and Masters of Public Health degrees at Tufts Medical School and completed her family medicine residency at Boston Medical Center. She is currently an attending physician at Bronxcare Health Systems in the Bronx, NY where ... Read More

  1. What Is Naltrexone? University of Arkansas for Medical Sciences. Accessed October 2022.
  2. Naltrexone. Substance Abuse and Mental Health Services Administration. September 2022. Accessed October 2022.
  3. What to Avoid when Taking Low-Dose Naltrexone. The Healthy Choice Compounding Pharmacy. Accessed October 2022.
  4. Effective Treatments for Opioid Addiction. National Institute on Drug Abuse. November 2016. Accessed October 2022.

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