Naltrexone Side Effects: Why Some People Feel Weird or Nauseous
Naltrexone is an FDA-approved medication used to treat alcohol use disorder. By blocking certain opioid receptors in the brain, it reduces the rewarding effects of alcohol and can help people drink less or stop drinking altogether.
Like many medications, however, naltrexone can cause side effects in some individuals. While many people tolerate the medication well, others may experience temporary symptoms as their body adjusts.
Understanding what these side effects are, why they happen, and how long they typically last can help people decide whether naltrexone may be right for them.
Key Facts About Naltrexone Side Effects
- Most people tolerate naltrexone well
- Common side effects include nausea, stomach discomfort, headaches, and fatigue
- Some people report feeling strange or “off” when starting the medication
- Side effects are usually strongest during the first few weeks of treatment
- Many symptoms improve within about 30 days as the body adjusts
Learn More: How Naltrexone Works: Experts Point of View
What Are the Most Common Side Effects of Naltrexone?
Most people who take naltrexone experience either mild side effects or none at all. When side effects do occur, they are usually most noticeable when someone first begins taking the medication.
Some of the most commonly reported naltrexone side effects include:
- Nausea
- Stomach discomfort or gastrointestinal upset
- Diarrhea
- Headaches
- Fatigue
- Sleep disturbances
- Feeling slightly “off” or different than usual
These symptoms are usually temporary and often improve as the body adjusts to the medication. Many people find that taking naltrexone with food or starting at a lower dose under medical supervision can help reduce these effects.
Why Does Naltrexone Make Some People Feel Weird?
Some people report feeling unusual when they first begin taking naltrexone. Common descriptions include feeling slightly foggy, strange, or mildly intoxicated.
This happens because naltrexone interacts with opioid receptors in the brain that influence reward, mood, and perception. While the medication blocks the receptors involved in alcohol’s pleasurable effects, it can also affect related systems that regulate how a person feels physically and mentally.
Because everyone’s brain chemistry is different, some people are more sensitive to these changes than others. For many individuals, these sensations fade as the body adapts to the medication.
Do Naltrexone Side Effects Go Away?
In most cases, yes.
Side effects are often most noticeable when someone first starts taking naltrexone. As the body adjusts, these symptoms frequently improve.
Many people find that side effects decrease within the first few weeks of treatment, and most adjustment occurs within about 30 days. During this time, healthcare providers may recommend starting with a lower dose and gradually increasing it to minimize discomfort.
If symptoms continue beyond this period or become severe, it may indicate that the medication is not the right fit for that individual.
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When Naltrexone May Not Be the Right Medication
While naltrexone works well for many people, it does not work for everyone. A small percentage of individuals experience side effects that persist even at lower doses.
When this happens, a physician may recommend adjusting the treatment plan or considering alternative medications. Individual biology plays a significant role in how someone responds to medication, which is why medical guidance is important during treatment.
How to Reduce Naltrexone Side Effects
If someone experiences mild side effects while taking naltrexone, several strategies may help reduce symptoms:
Start with a lower dose
Some providers begin treatment with a lower dose and gradually increase it as the body adjusts.
Take the medication with food
This can help reduce gastrointestinal symptoms such as nausea or stomach discomfort.
Allow time for adjustment
Many side effects improve during the first few weeks of treatment.
Stay in communication with a healthcare provider
If symptoms persist or become uncomfortable, a physician can help determine whether adjustments are needed.
Is Naltrexone Safe?
Naltrexone has been FDA-approved since 1984 for the treatment of alcohol use disorder and has been widely studied in clinical settings.
When prescribed and monitored appropriately, it is generally considered safe. As with many medications, healthcare providers may monitor certain health factors—such as liver function—during treatment to ensure the medication remains appropriate.
Anyone considering naltrexone should discuss their medical history and any current medications with a qualified healthcare professional before beginning treatment.
Does Naltrexone Cause Weight Loss?
Naltrexone itself is not typically prescribed for weight loss when used alone. However, it is sometimes used as part of combination medications designed to support weight management.
In those cases, the medication may influence appetite and reward pathways in the brain that affect eating behavior. This use differs from how naltrexone is prescribed for alcohol use disorder.
If weight changes occur while taking naltrexone, it is important to discuss them with a healthcare provider.
Medication as Part of Alcohol Use Disorder Treatment
Medication can be a helpful tool for people looking to change their relationship with alcohol. However, it is often most effective when combined with medical support and behavioral strategies.
Programs that combine medication with ongoing monitoring, coaching, and clinical guidance may help individuals build healthier habits and maintain long-term progress.
If you’re interested in learning more about treatment options for alcohol use disorder—including medications like naltrexone—working with a qualified healthcare provider can help determine the best path forward.
Do you want to regain control of your drinking? Ria Health uses medication-assisted treatment and 24/7 support to help its members drink less. Learn more about our program, or get started today.
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