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Naltrexone Side Effects and Uses for Alcohol Addiction: Is it Right for You?

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If you want to cut back or quit drinking, 12-step or abstinence-based programs aren’t the only options. In fact, research shows that many people have more success when they combine anti-craving medications like naltrexone with personalized one-on-one support, and are able to set their own goals around alcohol (rather than abide by the goals of a program).

One of the medications Ria Health prescribes for alcohol dependence is naltrexone. If you’re considering this drug, you’re probably wondering how safe it is. In this post, we’ll outline the side effects of naltrexone and whether it could be right for you.

What Is Naltrexone?

Naltrexone reduces alcohol cravings
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Naltrexone is an anti-craving medication that’s prescribed to treat alcohol use disorder.

It’s FDA-approved for alcohol dependence, but it was first used to help prevent relapse in people dependent on opioids. When someone uses an opiate drug like heroin or oxycodone, naltrexone stops the person from feeling the pleasure or sense of euphoria they usually do. That’s because naltrexone is an opiate antagonist—meaning it blocks the body from responding to endorphins.

Although alcohol isn’t an opiate drug, researchers have found that naltrexone works in a similar way with alcohol, by blocking alcohol-induced pleasure. Typically, a person takes naltrexone at the beginning of the day or when they anticipate drinking. They still feel the intoxicating effects of alcohol while taking naltrexone, but the pleasurable effects of alcohol decrease. Over time, as their brain stops making the connection between alcohol and pleasure, many people find it easier to stop drinking after the first or second drink. The drug works to gradually undo dependence.

Research on naltrexone has shown that it effectively reduces heavy drinking and cravings. Compared to patients who took a placebo, or fake medication, those who took naltrexone also had fewer relapse episodes.

What Are Naltrexone’s Side Effects?

Fortunately, naltrexone’s side effects are mild and relatively rare. A recent review of research1 concluded that there were only a few safety concerns related to using the drug for alcohol use disorder. In fact, the number of people who stop using naltrexone because of its side effects is about the same number as those who experience side effects from a placebo.

With that being said, there are a few side effects you may experience while your body is adjusting to the medication. These include:

  •       Headache
  •       Drowsiness
  •       Stomach pain
  •       Loss of appetite
  •       Dizziness
  •       Nausea or vomiting
  •       Nervousness
  •       Insomnia
  •       Joint pain
  •       Rash
  •       Muscle cramps
  •       Restlessness

The most commonly reported side effects are headaches and nausea. Women taking naltrexone may be more susceptible to nausea, but it usually subsides as they get into the routine of taking the medication. To prevent this side effect, you can take your medication with food or ask your doctor if they can start you at a lower dose and gradually increase it.

Naltrexone is also a good option for people who are concerned about experiencing alcohol withdrawal symptoms if they stop drinking. Because naltrexone works by helping a person to gradually decrease their drinking over an extended period of time, this process can minimize or even eliminate the impacts of alcohol withdrawal.

If side effects are severe or prolonged, you should tell your doctor.

Naltrexone can have other rare but serious side effects. Although it’s unlikely, you should contact your health provider if you experience:

  • Elevated blood pressure
  • Increased heart rate
  • Confusion
  • Depression or suicidal thoughts
  • Nightmares
  • Blurry vision
  • Allergic pneumonia (symptoms such as coughing, wheezing or breathing problems)

Like most drugs, it’s possible to overdose on naltrexone, possibly leading to coma or death. Do not take more than the recommended dose.

Does Naltrexone Have Long-Term Effects?

Naltrexone is effective but it isn’t a one-time magic pill. When you take it using the Sinclair Method, you’ll notice results over time. Even after you’ve cut back, your coach may still suggest taking it every time before you drink to keep yourself on track or further minimize your consumption. For this reason, you may be wondering if naltrexone has any long-term side effects.

There are no known side effects or problems caused by long-term use when taken as directed. With that being said, your doctor may recommend avoiding high doses of acetaminophen (ex. Tylenol). This is because it may increase your chances of liver damage while taking naltrexone.

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Is Naltrexone Safe During Pregnancy?

Women who are struggling to quit alcohol before or during pregnancy may wonder if naltrexone is a safe option.

How naltrexone may affect a fetus is unknown. Experts believe that it crosses the placenta, meaning that the drug could be transferred to the baby. A review of research on animals showed that naltrexone may cause developmental abnormalities, such as higher birth and organ weights and longer body lengths. It may also have developmental effects later on.

Although it hasn’t been shown to cause birth defects, studies on rats and rabbits show that high doses may cause miscarriage. It’s important to understand that these results may not translate to humans. Also, the doses used on animals are much higher in comparison.

If you are pregnant or planning on becoming pregnant while taking naltrexone, you should talk to your doctor. If you are expecting and considering naltrexone, your doctor may still recommend it. He or she will weigh the benefits and risks to assess whether it’s the best option. For example, alcohol has well-known adverse effects on a fetus. Even though naltrexone also has risks, the consequences of binge drinking could affect a fetus more. In these cases, a healthcare provider will determine which treatment is less likely to harm the baby.

Is Naltrexone Addictive?

Some people are afraid that their addiction to alcohol may morph into a dependence on their medication. The concern is valid since some alcohol withdrawal medications, such as benzodiazepines, are highly addictive. However, it’s not possible to become addicted to naltrexone, according to the National Institute on Alcohol Abuse and Alcoholism.

The medication isn’t habit-forming, and doesn’t cause physical or psychological dependence. You won’t feel any sort of buzz, high, or sense of euphoria. In fact, when someone takes the drug, they usually don’t feel anything other than a decreased desire to drink.

Does Naltrexone Impact Your Mood?

Being an anti-craving medication, naltrexone works by stopping you from feeling the endorphins alcohol releases. Some people wonder if the drug also blocks healthy endorphins, impacting your mood. Endorphins can be released from normal activities, such as:

  • Exercise
  • Food
  • Sex
  • Getting a massage
  • Meditation
  • Laughing

The current evidence suggests that naltrexone only impacts endorphins released by alcohol.

How is it possible that the drug can “choose” which endorphins to block? One theory is that alcohol elevates hormones in a different way. While drinking activates the gabaergic system, other behaviors don’t. Because of this, the medication seems to specifically target alcohol reward.

Naltrexone also does not directly affect serotonin or dopamine—two chemicals that help regulate emotions. Since it works in the body’s opioid system, it doesn’t impact neurotransmitters. A 2006 study concluded that even though depression is cited as a naltrexone side effect, it shouldn’t be considered common. In fact, they found that adhering to naltrexone treatment may be associated with fewer depressive symptoms.

In general, people don’t lose pleasure from other enjoyable activities while taking naltrexone. With that being said, in rare cases, a patient will report emotional changes. These should always be discussed with your doctor.

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Does Naltrexone Affect Social Bonding?

While mood may not be impacted, the bad news is some evidence suggests naltrexone may change the way we process social situations. In a 2016 study, 34 volunteers received a placebo or naltrexone. Researchers found that the medication:

  • Significantly increased volunteers’ tendency to look at emotional faces (vs. non-emotional faces) first.
  • Slowed down the time it took for volunteers to identify facial reactions of sadness and fear.
  • Slightly decreased volunteers’ arousal when looking at social and non-social pictures.

There is also some evidence that the medication may affect social attachment. A 2016 study on healthy adults concluded that naltrexone reduced feelings of connection, suggesting that it may affect their ability to bond with others.

A 2019 study investigated this impact further by looking at how the drug affects social warmth (the feeling of being connected to others).

Social and physical warmth leads to increased activity in two parts of the brain: ventral striatum and middle-insula. Researchers also established that brain activity caused by social warmth was related to social connection. What’s interesting is that naltrexone disrupted this; brain activity in those two areas decreased. The results suggest that physical and social warmth may be dependent on opioid receptors. Since naltrexone blocks these receptors, social connection may be affected.

Is Naltrexone Safe?

If you have a naltrexone prescription for alcohol dependence, you’ll probably notice a warning label about hepatotoxicity, or drug-induced liver damage. However, research shows that it’s only unsafe if it’s taken for extended periods in doses of 300mg or higher. Doctors usually prescribe naltrexone for alcohol use disorder at much lower doses, typically 50mg.

If a patient is already suffering from liver damage or disease, their doctor may recommend an anti-craving drug that’s not metabolized in the liver, such as baclofen.

While the drug is safe to take for most people, it does not get rid of the risks of alcohol. Naltrexone might block the pleasurable effects of alcohol, but you can still get drunk while taking the medication. This means that you still need to be aware of how much you’re drinking. You could still experience bad coordination, impaired judgment, or blackouts.

Is Naltrexone Right for You?

Before prescribing you naltrexone, your doctor will assess if it’s the right anti-craving medication for you.

Naltrexone may be right for you if:

  •       You experience intense cravings to drink
  •       You’re looking to cut back your drinking or quit altogether
  •       You want to change your drinking habits
  •       You’re of childbearing age and using birth control
  •       Your liver is healthy
  •       A doctor or counselor closely monitors your medication use
  •       Naltrexone may be especially effective if you have a family history of alcohol dependence

Naltrexone may not be right for you if:

  •   You have liver damage or disease (your doctor may recommend another anti-craving drug)
  •   You have an opioid prescription or use an opioid drug
  •   You’re prescribed disulfiram, another drug for problem drinking commonly known as Antabuse
  •   You’re pregnant (unless the benefits outweigh any potential risks)
  •   You have a sensitivity to naltrexone or similar drugs

Overall, naltrexone is safe and effective for many people who have alcohol cravings.

Read more about what it’s like to take naltrexone.

Summary of Naltrexone’s Side Effects:

Naltrexone is considered a non-addictive, safe drug, but some people may experience mild side effects when they begin taking it. Prolonged or severe side effects are rare and should be reported to your doctor. Naltrexone works by blocking endorphins released by alcohol, but doesn’t seem to affect those released by other activities. It also does not interact with neurotransmitters, meaning that it shouldn’t affect your mood. On the other hand, some research suggests it may affect how we perceive social situations or connections.

Ria Health combines medication and counseling to help you reach your goal—whether it be to drink less or stop altogether. Join our at-home program today.


Written By:
Riannon Westall
Toronto-based health writer. Background in newsroom journalism, content marketing, and research.
Reviewed By:
Evan O'Donnell
Writer specializing in targeted, informative content. Dedicated to making the abstract accessible.
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