Naltrexone Uses And Mechanism Of Action. How Does It Work?

Last Updated: June 24, 2020

Authored by Olivier George, Ph.D.

Reviewed by Michael Espelin APRN

Naltrexone uses are wide-ranging and highly varied. Some things naltrexone is used for include the treatment of certain addictions, pain disorders, autoimmune diseases, and ulcerative colitis. Patients need to understand the various Vivitrol uses and how the medication works on the body.

The FDA-Approved Naltrexone Uses

There are just two FDA-approved naltrexone uses: the management of alcohol dependence and the treatment of opiate addiction. These uses of Vivitrol are approved because they have been rigorously tested and found to have a positive impact. As such, naltrexone is used for drug abuse treatment and alcohol rehabilitation programs across the country.

Naltrexone For Alcohol Dependence

When what Vivitrol is used for is alcohol dependence, the medication functions by blocking the euphoric feelings drinking can produce. How the medication is taken will vary based on the type of therapy it is being used at.

Naltrexone For Opioid Addiction

When what Vivitrol is used for is opioid addiction, daily medication is not favored. Instead, a Vivitrol shot for opiates addiction or the implant version are used. To use Vivitrol for this purpose safely, the user will need to be off opioid medication before starting treatment.

Off-Label Naltrexone Uses

While off-label Vivitrol uses are not approved by the FDA, doctors will employ them based on limited research and their own observed results. Naltrexone off-label uses are highly varied. In nearly all cases, this type of use exclusively relies on low-dose naltrexone therapy, which requires taking daily pills over injections and implants.

Low-Dose Naltrexone For Pain

Low-dose naltrexone (LDN) uses for pain are quite common. Limited studies have found it to have a positive impact on symptom severity in several pain disorders. However, its use in pain management is still considered experimental.


Studies conducted by Stanford University show that the drug is highly effective in the treatment of multiple fibromyalgia symptoms, ranging from pain to fatigue. However, naltrexone for fibromyalgia treatment has only been tested in short-term studies. Long-term safety of LDN for fibromyalgia is unknown.

Chronic pain

Low-dose naltrexone for chronic pain treatment is another application of the drug. As with fibromyalgia, the studies on its safety and efficacy are limited, but it does seem to address chronic pain caused by inflammation well.

Nerve pain

The use of low-dose naltrexone for peripheral neuropathy is different from its use in treating other pain conditions. This is because it has been found not just to treat the pain, but potentially reverse the nerve damage causing it. LDN for nerve pain can be used in those with nerve damage from accidents, diabetes, and other medical conditions.


Low-dose naltrexone for rheumatoid arthritis is quite common. However, it is currently being assessed on its effectiveness in the treatment of varying types or arthritis, including osteoarthritis and psoriatic arthritis. For now, doctors mostly stick to LDN for rheumatoid arthritis, waiting to see if it is effective in the treatment of other forms of the disease.

Low-Dose Naltrexone For Depression And Anxiety

Use of LDN for depression and anxiety treatment is becoming more common. However, there is some controversy here. Limited research indicates that Vivitrol could actually cause depression rather than treat it. Taking low-dose naltrexone for anxiety may also be problematic, as while it can ease symptoms in some, it can amplify them in others.

Low-Dose Naltrexone For Autoimmune Diseases

The use of naltrexone low-dose therapy for autoimmune conditions came about almost by accident. Dr. Bernard Bihari observed that AIDs patients using Vivitrol for addiction management also saw immune modulating effects. From there, he and other doctors began to look into LDN as autoimmune disease treatment. What they found is that low-dose naltrexone for autoimmune conditions seems to have positive results in clinical tests, though more research is needed.


To date, there has been no low-dose naltrexone for cancer clinical trials. However, there have been case studies where cancer patients have used the drug and seen benefits. These indicate that cancer patients who cannot use chemotherapy might benefit from Vivitrol use.

Multiple Sclerosis

In a few small, randomized studies, the drug has been shown to have a positive impact on multiple sclerosis symptoms. While it does not cure anything, it does seem to allow patients with the disease to live a more comfortable life. However, low-dose naltrexone for multiple sclerosis needs to be further tested.

naltrexone multiple sclerosis

Hashimoto’s disease

Another application of the medication is in the low-dose naltrexone therapy for Hashimoto’s. While it does not eliminate or mask symptoms of the disease, it does slow down their progression, which minimizes the physical destruction the disease causes over time.


The use of low-dose naltrexone for lupus is gaining in popularity. Limited studies have found that it does not just slow or stop the progression of the disease, but can actually reverse it. Clinical trials establishing its efficacy are ongoing.

Crohn’s disease

For Crohn’s patients, Vivitrol has been very promising. This is because it has been shown to help put the disease into remission. However, the studies are so small in scope that it cannot be said to be definitively proven that low-dose naltrexone for Chron’s is the reason patients have entered remission.

Low-Dose Naltrexone For Lyme Disease

Because it seems to have anti-inflammatory properties, LDN for Lyme disease can be effective in managing symptoms. At the moment, no clinical trials have proven it effective, but doctors still use it for this application.

Low-Dose Naltrexone For Ulcerative Colitis

While studies are not conclusive, limited research has shown that Vivitrol can put irritable bowel syndrome into remission. As it falls under the umbrella of IBS, many doctors are using LDN for the treatment of ulcerative colitis.

Low-Dose Naltrexone For Parkinson’s

LDN for Parkinson’s treatment does not affect the overall disease. However, it can improve the impulse control the disease tends to inhibit. Clinical trials to prove its efficacy are ongoing.

Low-Dose Naltrexone For Chronic Fatigue Syndrome

The exact origins of chronic fatigue syndrome are not known. However, low-dose Vivitrol therapy seems to improve the condition. As with many other conditions, studies on its effectiveness are ongoing.

low dose naltrexone chronic fatigue syndrome

Low-Dose Naltrexone For Bipolar Disorder

Bipolar disorder consists of severe depression and severe mania. As Vivitrol can be effective in depression management, it is sometimes used in treating the depressive side of bipolar disorder.

Low-Dose Naltrexone For OCD

Vivitrol is used in low doses for the treatment of OCD. Small studies have shown it to be effective at giving patients greater impulse control. Still, more research is needed.

Naltrexone Mechanism Of Action

The drug mechanism of action is not fully understood. What naltrexone does is affect opioid receptors, especially the mμ opioid receptor. This prevents the receptors from processing things like opiates and alcohol in a way that will cause euphoria.

While this explains some of how naltrexone works, it doesn’t cover everything it does. It is clear why it works in the management of addiction, but this does not explain the majority of its off-label uses. Also, some Vivitrol side effects cannot be explained by its mechanism of action.

How Does Naltrexone Work?

How Naltrexone works will depend on how it is administered. If taken orally, it is absorbed by the gastrointestinal tract and then makes its way to the opioid receptors in the brain. If taken by injection or implant, it reaches the brain directly through the bloodstream. Once there, it actually occupies the opioid receptors in the brain, effectively blocking them from being impacted by any other substance. Because it blocks these receptors, naltrexone cannot get one high.

How Long Does It Take Naltrexone to Work?

Vivitrol is rapidly absorbed by the body and metabolized. As such, it does not take long for it to go into effect. Users can experience full effectiveness within an hour of taking the medication, depending on the method of administration. How long it takes for naltrexone to work will depend on the form the drug takes and factors unique to the user.

Best Time To Take Naltrexone

Often, patients wonder if they should take naltrexone in the morning or at night. The decision is personal. When to take naltrexone depends on how the person reacts to the medicine and what the doctor prescribes.

Naltrexone Contraindications

Even if someone suffers from a condition the medicine can treat, the drug contraindications can mean the user is unable to take the medication.

If there is a concern, users can talk to their doctor about other medications, considering the difference between naloxone and naltrexone if the urgent help is needed.

Getting Help With Substance Abuse

If someone is interested in Vivitrol because they want to end their substance abuse, the best course of action is to enroll in an alcohol or drug rehab. There, they can get the best therapies for them, which may include the use of naltrexone. With many centers across the country, the right fit is out there.

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Published on: June 7th, 2019

Updated on: June 24th, 2020

About Author

Olivier George, Ph.D.

Olivier George is a medical writer and head manager of the rehab center in California. He spends a lot of time in collecting and analyzing the traditional approaches for substance abuse treatment and assessing their efficiency.

Medically Reviewed by

Michael Espelin APRN

8 years of nursing experience in wide variety of behavioral and addition settings that include adult inpatient and outpatient mental health services with substance use disorders, and geriatric long-term care and hospice care.  He has a particular interest in psychopharmacology, nutritional psychiatry, and alternative treatment options involving particular vitamins, dietary supplements, and administering auricular acupuncture.


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