Naltrexone, sold under brand names such as ReVia, Vivitrol, and Depade, is a medication for opioid dependence and alcohol dependence. As a medication-assisted treatment (MAT), Naltrexone was initially approved by the U.S. Food and Drug Administration (FDA) in 1984 to treat opioid addictions such as heroin, morphine, and oxycodone. And it was later approved for treating alcohol use disorder in 1994.
Naltrexone is available as a daily dose in a pill form (ReVia and Depade) or as a monthly intramuscular injection (Vivitrol) for treating alcohol and opioid use disorders. Naltrexone is considered unique to other substance use disorder medications because it treats both opioid and alcohol use disorders. When used in combination with behavioral therapy, counseling, and aftercare support, naltrexone is a highly effective medication.
of alcohol or opioids, which can make it easier to pause, reflect, and focus on recovery.
If cravings don’t change right away or side effects feel uncomfortable, that doesn’t mean the medication isn’t working. A healthcare provider can help adjust dosage, timing, or supportive care as your body adapts.
Naltrexone can be prescribed to those who are currently using alcohol. While naltrexone does not necessarily stop you from drinking or reverse the intoxicating effects of alcohol, it does gradually reduce the amount that you drink. However, it may take many weeks after starting naltrexone to notice a reduction in opioid or alcohol cravings.
It belongs to a class of medications known as opioid antagonists. This medication delivers powerful opioid-blocking effects through both oral naltrexone and injectable naltrexone options. Naltrexone works by blocking the sedative and intoxicating effects of opioids by binding to the endorphin receptors in the body and blocking opioid receptors in the brain. This function, combined with behavioral health therapies like cognitive behavioral therapy, helps maintain abstinence and prolong recovery. Naltrexone is effective in substance use disorder maintenance treatment because it’s a non-narcotic medication with a low risk of misuse. Naltrexone can be prescribed and administered by any practitioner licensed to prescribe medications since it is not a controlled medication.
Individuals must remain opioid-free for at least seven days after their last use of short-acting opioids and 10-14 days after their last use of long-acting opioids before initiating naltrexone treatment to lessen the risk of rapid opioid withdrawal syndrome.
Naltrexone works by blocking opioid receptors in the brain. These receptors are involved in the pleasurable and reinforcing effects associated with alcohol and opioids.
When these receptors are blocked:
Unlike some medications used in addiction treatment, naltrexone does not replace opioids or cause physical dependence. It doesn’t sedate the nervous system or alter consciousness. Instead, it changes how the brain responds to substances.
Because of this, naltrexone is often most effective when used as part of a broader treatment plan that includes medical guidance, behavioral support, and mental health care.
Other medications, such as Suboxone, work differently and may be recommended depending on individual needs.
Oral naltrexone absorbs quickly and begins to work within an hour after consumption. The effects of the 50-mg oral tablet can last for 24 to 36 hours. The duration of higher doses is longer lasting, with 100 mg lasting 48 hours and 150 mg lasting 72 hours. Naltrexone usually reaches its peak within one hour of dosing.
The dosing of intramuscular extended-release naltrexone (Vivitrol) is 380 mg given as a monthly injection. Vivitrol reaches its initial peak around two hours after administration, followed by a second peak within two to three days. Two weeks after administration, the medication’s concentration in the body begins to decline. It can, however, be detected for up to 50 days after initial administration.
Many people start wondering what will change shortly after beginning naltrexone. While everyone’s experience is different, the first week often comes with some noticeable shifts.
During the first few days, some people experience:
Naltrexone does not create a “high” or immediate sense of relief. Instead, it works by reducing the rewarding effects
Naltrexone supports recovery by reducing the physical drivers that make alcohol or opioid use feel rewarding. Over time, this can make cravings easier to manage and give people more space to focus on their goals, relationships, and overall well-being.
Because naltrexone does not cause dependence or replace opio in the body, it can be used safely as part of a long-term recovery plan. Many people find that when the urge to drink or use becomes less intense, it’s easier to engage in therapy, build coping skills, and make sustainable changes.
Naltrexone is most effective when combined with behavioral health support, counseling, and medical guidance. This whole-person approach helps address not just substance use, but the stress, mental health concerns, and life challenges that often influence recovery.
Recovery looks different for everyone. For some, naltrexone is a short-term support. For others, it plays a longer role alongside therapy and peer support. A healthcare provider can help determine how it fits into an individualized treatment plan.
In addition to its beneficial effects, naltrexone can also cause certain negative effects. However, the majority of these side effects are minor and fade away with time.
Common side effects of naltrexone include:
Naltrexone can cause severe side effects in rare circumstances. These side effects may include:
Medical professionals advise that you discuss the following conditions with your healthcare provider before starting naltrexone treatment to lessen the chance of side effects. These conditions include:
Your healthcare practitioner can determine the safest dose of naltrexone or recommend an alternative medicine based on these conditions.
Determining exactly how long naltrexone is detectable in your body depends on many variables. These variables include the form of naltrexone taken and the type of drug tests being utilized.
The timetable for detecting naltrexone in the body also depends upon factors such as:
These variables make it almost impossible to determine an exact time at which naltrexone will show up on blood tests or other drug screening methods. However, naltrexone is usually detected in the urine within the first four to six hours following administration and for up to 24 hours in the blood and saliva. And it can also be detected in the hair for up to 90 days. Vivitrol, on the other hand, can remain detectable in drug tests for months.
Typically, for a drug test to detect a certain substance, that substance must be specifically tested. And naltrexone is not generally included in any of the typical testing panels.
Naltrexone may interact with other medications, resulting in severe side effects. Since this medication is used to treat alcohol and opioid addiction, individuals on naltrexone must avoid certain medications to prevent unpleasant withdrawal symptoms. Before starting naltrexone, inform your healthcare provider of any other medications you’re taking, including over-the-counter medicines and herbal remedies.
Medications that interact negatively with naltrexone include:
It’s theoretically possible to overdose while on naltrexone if a person takes large amounts of opioids or alcohol in an attempt to counteract the effects of naltrexone or in case of a relapse after a period of maintained abstinence.
Signs and symptoms of an overdose include:
Opioid overdose is a medical emergency that requires immediate medical attention.
Naltrexone can be a powerful part of recovery, especially when combined with counseling, behavioral health support, and ongoing medical care. Together, these approaches help reduce cravings while supporting the emotional and practical changes that make recovery sustainable.
Medication-assisted treatment programs combine medications like naltrexone with counseling and ongoing support.
If you or someone you love is exploring treatment options, you don’t have to figure it out alone. Eleanor Health offers whole-person care for alcohol and opioid use disorders, with support that’s designed to meet you where you are.
If you are seeking help with your loved one’s addiction, contact us today or complete our quick contact form below, to speak with an addiction treatment specialist.
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