How Long Does Naltrexone Last?

Naltrexone, also known as Revia and Vivitrol, is a prescription medication that can reduce cravings for opiates and alcohol, as well as block their euphoric effects. The short-acting form of naltrexone (Revia, Depade) can have effects that last 24 hours on average, while long-acting naltrexone (Vivitrol) has effects that last about one month.

How long this medication lasts depends on the formulation taken, the dose taken, and other personal and biological factors.

Read more about using Naltrexone for alcohol and opioid addiction

How Long The Effects Of Oral Naltrexone Last

Oral naltrexone (Revia, Depade) comes in pill form. It is typically directed for use once a day, once every other day, or once every three days.

Average duration of effects, by dosage:

• 50 milligrams (mg): 24 hours
• 100 milligrams (mg): 48 hours
• 150 milligrams (mg): up to 72 hours

The standard dosage of naltrexone for adults is 50 mg once a day. Your doctor may prescribe a higher or lower dosage based on personal health needs.

How Long The Effects Of Injection Naltrexone Last

Vivitrol is an extended-release (long-acting) form of naltrexone that is administered intramuscularly once every four weeks, or once a month. The effects of Vivitrol peak twice after administration: first, about two hours after administration, and then once more about two to three days after administration.

Concentrations of Vivitrol in the body begin to decline about 14 days after administration in most people. This doesn’t necessarily affect its efficacy, however. Side effects of Vivitrol, such as nausea or reactions at the injection site, will generally go away within the first few days after receiving Vivitrol.

What Can Affect How Long Naltrexone Lasts?

How long the effects of a medication last can vary from person to person, depending on how fast the body breaks down the substance in a person’s system.

Factors that can influence this include:

• age of the person
• use of other medications
• metabolic rate
• liver and kidney function

Certain health conditions, such as liver disease, may affect the metabolism of naltrexone in the body, which can in turn affect the strength and duration of drug effects.

What Happens When Naltrexone Effects Wear Off

If someone misses a dose of oral naltrexone or doesn’t receive their monthly Vivitrol injection on time, the medication’s blocking effects gradually diminish, leaving opioid receptors available for opioids or alcohol to activate. This means the person becomes vulnerable to experiencing the full euphoric effects again if they relapse, potentially reigniting cravings and addiction.

A critical danger when naltrexone wears off is dramatically increased overdose risk if someone uses opioids. Because naltrexone blocks opioid receptors during treatment, the body may lose tolerance to opioids. If someone relapses after stopping naltrexone, taking the same amount of opioids they used before treatment can lead to fatal overdose due to reduced tolerance.

Take naltrexone consistently as prescribed, attend all scheduled Vivitrol appointments, and contact your doctor immediately if you miss a dose.

Call Today To Find Naltrexone Treatment Options

Naltrexone is a prescription medication that is proven to help people maintain their sobriety by reducing cravings for alcohol and opioids. If you’re looking for naltrexone treatment for yourself or a loved one, browse our directory or reach out to the Substance Abuse and Mental Health Services Administration (SAMHSA) to find an addiction rehab center near you.

Written by the Addiction Resource Editorial Staff