Naltrexone is used in medication assisted treatment for opioid addiction. As with any other medication, naltrexone can come with side effects. If your doctor has prescribed this medication, it is important to understand its risks and benefits. One potential side effect people may worry about when beginning medication assisted treatment with naltrexone is feelings of sleepiness. So, does naltrexone make you sleepy? Learn the details below. 

What Is Naltrexone?

Naltrexone is a prescription drug utilized in medication-assisted treatment of both alcohol use disorder and opioid use disorder. It is taken daily as a pill for the treatment of alcohol use disorder, and it is approved as an intramuscular injection for opioid use disorder. 

The intramuscular form of naltrexone is extended release and given once a month via injection. Naltrexone is typically used alongside counseling and other behavioral interventions for treating substance use disorders. It works by blocking euphoric and sedative effects of opioids. It also blocks opioid receptors, which reduces drug cravings. 

Naltrexone injection is often marketed under the brand name Vivitrol

Does Naltrexone Make You Sleepy?

Naltrexone effects can include feelings of sleepiness. In fact, naltrexone warnings indicate that patients taking this medication for alcohol use disorder commonly experience dizziness, sedation, and drowsiness. In addition, individuals prescribed naltrexone for the treatment of opioid use disorder may experience naltrexone insomnia, which can lead to feelings of sleepiness during the day if patients are unable to get a sufficient amount of sleep at night. 

Clinical trials conducted with naltrexone have revealed that among individuals taking the medication for alcohol use disorder, rates of insomnia with naltrexone are only slightly higher than seen in people taking a placebo. Feelings of sleepiness and sedation occur in 5% of people taking naltrexone for alcohol use disorder, compared to just 1% of those taking placebo, indicating that naltrexone tiredness is a relatively common side effect for individuals with alcohol use disorders. 

In people taking naltrexone for opioid use disorder, 6% experience naltrexone insomnia, compared to just 1% on a placebo. When naltrexone causes sleep disturbances, patients may struggle with sleep deprivation, which can lead to daytime sleepiness. 

Low dose naltrexone side effects may be milder when compared to the side effects of higher doses. For instance,clinical trials with patients in treatment for alcohol use disorder found that 8% experienced sedation and sleepiness when taking 400 mg of naltrexone, compared to 4% of patients taking 190 mg of naltrexone. 

A recent research report evaluated the results of 11 different studies including over 1,000 patients and found that extended release, injectable naltrexone tended to produce more side effects than oral naltrexone did. Insomnia and fatigue were both listed as common adverse naltrexone effects, and fatigue was the most commonly reported side effect. 

In summary, the answer to, “Does naltrexone make you sleepy?” can be yes, for some people. Naltrexone sleep problems, such as insomnia, can lead to feelings of sleepiness. Naltrexone dizziness is also a commonly reported side effect, and it can cause some people to feel sleepy. Sedation and sleepiness itself is also reported among naltrexone users. 

Keep in mind that while sleepiness is a commonly reported side effect of naltrexone, it occurs only in a minority of people taking this medication. You might experience sleepiness when taking naltrexone, but many patients find that the benefits of this medication outweigh its side effects.

Other Side Effects Of Naltrexone

Some other side effects of naltrexone are as follows.

Gastrointestinal Effects

People taking naltrexone may experience gastrointestinal side effects, such as nausea and vomiting.


Naltrexone can cause various forms of pain for some people. These include muscle cramps, toothache, headache, and joint pain.

Serious Side Effects

In rare cases, naltrexone can cause serious side effects, including the following:

  • Liver damage: Signs such as stomach pain that does not go away within a few days, dark-colored urine, tiredness, and yellowing of the eyes are indicative of naltrexone liver damage. 

  • Severe allergic reactions: Some people may experience breathing problems, swelling, and skin rash, which are indicative of an allergic reaction to naltrexone. 

  • Injection site reactions. Pain, lumps, swelling, blisters, and open wounds at the naltrexone injection site are possible. 

Overdose Risk

Patients taking naltrexone are at increased risk of opioid overdose, because the drug can make them more sensitive to the effects of opioids. Some patients may attempt to overcome naltrexone’s opioid-blocking effects by taking very large doses of opioids. This also increases the risk of overdose. 

Other Naltrexone Effects 

Other side effects of naltrexone include reduced appetite and cold symptoms. 

Naltrexone FAQs

If you’re looking for information on naltrexone side effects, the answers to the following frequently-asked questions may be beneficial. 

How Does Naltrexone Make You Feel?

Each person’s experience with naltrexone will be different, depending upon their health history and unique needs. Common side effects of naltrexone include nausea, sleepiness, headache, joint and muscle pain, toothache, insomnia, dizziness, vomiting, and cold symptoms. For many people, side effects are mild. Talk with your doctor if adverse naltrexone effects persist or are bothersome.

Does Naltrexone Make You Feel Weird?

Some people may experience dizziness and sedation with naltrexone, which can feel weird or unpleasant. 

Can Naltrexone Cause Depression? 

Naltrexone warnings indicate that depression and suicidal thoughts are possible when taking this medication. This reaction is infrequent but occurs more often in those on naltrexone when compared to patients taking a placebo. Depression seems to be more common among those taking naltrexone for opioid use disorder compared to alcohol use disorder and more common among those on oral naltrexone compared to injectable naltrexone. 

What Are The Most Common Side Effects Of Naltrexone? 

Common side effects of naltrexone include nausea, sleepiness, headache, joint and muscle pain, toothache, insomnia, dizziness, vomiting, and cold symptoms.

Should Naltrexone Be Taken At Night?

Naltrexone is often given in an injectable version, once per month. If you are taking oral naltrexone each day, and you experience naltrexone tiredness, you may benefit from taking the medication at night. Consult with your doctor about the best time to take your medication. 

Does Naltrexone Make You Sick?

Some people experience side effects including cold symptoms, nausea, vomiting, and headache while taking naltrexone. If you experience these side effects, you may feel sick. Discuss these symptoms with your doctor if they persist. 

Consult With Online MAT Doctors Through Confidant Health 

If you’re looking for convenient medication assisted treatment services, Confidant Health is here to help. With our app, you can receive online medication assisted treatment from the privacy and comfort of home. Download our app today, on either the Apple Store or the Google Play Store, to begin.