How Long Does Naltrexone Stay In Your System?

Disclaimer: This article is for educational purposes only and does not replace expert medical or mental health advice. Naltrexone prescription and dosage require a comprehensive evaluation by a qualified clinician. So, always refer to a board-certified physician for specific direction or treatment.

Naltrexone is a U.S. Food and Drug Administration (FDA)-approved opioid antagonist prescription medication used to treat opioid and alcohol use disorders, as it reduces cravings and prevents relapse. How long naltrexone stays in your system mainly depends on the dosage, frequency of use, and metabolism rates. Typically, naltrexone stays in your body for 24 hours. However, depending on the test conducted, it can be detected for even longer.

Naltrexone has a half-life of an estimated 4 hours. This means it takes 4 hours for the medication to be reduced in your body by half, then another half of the remaining half, and so on. Typically, it takes 4 - 5 half-life cycles until a medication is entirely cleared out of your system.

Why This Timeline Matters: Tolerance and Overdose Risk

Opioid tolerance decreases while you are taking naltrexone. If you stop taking naltrexone and later return to an opioid dose your body was previously used to, that dose can now be fatal. Anyone considering stopping naltrexone should talk to their prescriber first, and it is worth having naloxone (Narcan) on hand regardless.

On average, naltrexone stays in your system for up to 24 hours. However, depending on the type of test conducted, it can be detected for even longer.

How Long Does Naltrexone Stay In Your Urine?

Naltrexone can be detected in your urine for only 4 - 6 hours after the last dose. One of the most commonly used drug tests, it is easy to administer and inexpensive.

How Long Does Naltrexone Stay In Your Saliva?

Naltrexone can be detected in your saliva for up to 24 hours. Saliva tests are the least invasive and are easy to administer as well.

How Long Does Naltrexone Stay In Your Blood?

Naltrexone can be detected in your blood for up to 24 hours. As blood tests are slightly more invasive than the other tests, they are not as commonly used except in clinical settings.

How Long Does Naltrexone Stay In Your Hair?

Naltrexone can be detected in your hair for up to 90 days. However, as hair tests are time-consuming and expensive, they are not as commonly used except to establish a history of substance use.

Naltrexone stays in your system for up to 24 hours on average, but there are some factors that can have an impact on this:

• Dosage and Frequency: Higher doses and greater frequency of use can slow down the elimination time.
• Metabolism: Faster metabolism rates ensure faster naltrexone elimination from the body.
• Age: Age impacts metabolism, so aging can slow down the elimination.
• Liver and Kidney Functioning: The liver and kidneys play a crucial role in metabolism and excretion. So, pre-existing liver or kidney conditions can adversely impact the elimination rate
• Body Mass: Greater body mass can slow down the elimination rate.

While many factors can impact how long naltrexone stays in your system, maintaining physical activity, eating nutritious meals, and keeping your body hydrated at all times support your overall health and help with clearing naltrexone from your body.

The Substance Abuse and Mental Health Services Administration (SAMHSA) reports that naltrexone is effective in treating both opioid and alcohol use disorders.

For opioid misuse, the long-acting injectable formulation is specifically effective, as it blocks opioid receptors, preventing the person from experiencing the euphoric effects of opioids. It is particularly effective in preventing relapse, especially among those who have been sober and are committed to recovery.

For alcohol misuse, naltrexone reduces cravings and decreases the rewarding effects of alcohol by blocking endorphin receptors in the brain. It strengthens sobriety after detoxification (detox). It is effective in maintaining recovery, especially when combined with behavioral therapies and peer support.

Why You Cannot Start Naltrexone Right After Using Opioids

For opioid use disorder specifically, naltrexone cannot be started while opioids are still in your system. Because naltrexone blocks opioid receptors, giving it to someone who is still physically dependent on opioids can trigger precipitated withdrawal - a sudden, severe withdrawal reaction that can be serious enough to require hospitalization. This is why FDA prescribing information recommends an opioid-free interval of at least 7 to 10 days before starting naltrexone for those coming off short-acting opioids - longer, up to two weeks, for those coming off methadone or buprenorphine. Your prescriber will confirm you are ready before starting.

Oral Naltrexone vs. Vivitrol

Naltrexone is available as a daily oral tablet or as Vivitrol, a long-acting injectable form given once a month. Both contain the same medication and work the same way in the brain - the difference is how long a single dose lasts. Oral naltrexone needs to be taken daily to maintain its blocking effect, while a single Vivitrol injection maintains that effect for about four weeks, which can reduce the daily burden of remembering a dose.

As the medication clears from your system on the timeline described above, its opioid-blocking effect fades along with it, and any tolerance you previously built up to opioids will have decreased. This is part of why stopping naltrexone carries real risk, as covered above.

Naltrexone is highly effective as a generic opioid antagonist; it blocks the effects of opioids and alcohol and reduces the cravings for these substances. At the NuView Treatment Center, naltrexone is integral to medication-assisted treatment (MAT) programs, which combine the benefits of behavioral therapies and medication management for effective and lasting recovery from opioid and alcohol misuse.

Please contact us at (323) 307-7997 to connect with our experts and explore your healing options today!

What are the different types of drug tests used to detect naltrexone in your system?

• Urine Tests: Can detect Percocet for 4 to 6 hours.
• Saliva Tests: Can detect Percocet for up to 24 hours.
• Blood Tests: Can detect Percocet for up to 24 hours.
• Hair Tests: Can detect Percocet for up to 90 days.

What are the common brand names for naltrexone?

The common brand names that naltrexone is sold under are Contrave, Embeda, Mysimba, and Vivitrol.

How long does it take for naltrexone to take effect?

When taken orally or by injection, naltrexone takes effect within 1 hour.

Is naltrexone addictive?

Naltrexone is not generally considered to be addictive.

Is naltrexone effective as treatment?

SAMHSA says that naltrexone can be highly effective in treating opioid and alcohol use disorders. Medication prescription and management must only be done under the close supervision of a board-certified physician or psychiatric practitioner, as individual outcomes can vary.