How Long Does Naltrexone Stay in Your System?

Detection Timetable Depends on Many Variables

Bottle of Revia with pills

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Naltrexone is prescribed to assist people who are quitting alcohol or opiates. It is marketed as ReVia, Vivitrol, and Depade. It blocks the effects of opiates and can reduce the craving for alcohol. If you have been prescribed naltrexone, you may wonder how long it stays in your system and whether it may be detectable on lab tests.

It's important not to start naltrexone until all opiates have been out of your system for seven to 10 days or you may risk acute opioid withdrawal effects. Taking any opiates or drinking alcohol while you still have naltrexone in your system is dangerous.

Because it blocks opiate receptors in your body, you may have a serious reaction to opiates that can lead to injury or be lethal. Narcotic pain medications won't work and you need to discuss alternatives with your doctor.

Variations in How Long Naltrexone Is Detectable

Your doctor may order lab tests for naltrexone to see if you are taking the medication as prescribed. It is wise to inform the laboratory that you are taking naltrexone any time you must send blood, urine, saliva, or hair for testing.

Trying to determine exactly how long naltrexone is detectable in the body depends on many variables. This includes what form of the medication you are taking, whether the oral pill form or the once-a-month injection, and which kind of drug test is being used.

Naltrexone can be detected for a shorter time with some tests but can be "visible" for up to three months in other tests.

The timetable for detecting naltrexone in the system is also dependent upon each individual's metabolism, body mass, age, hydration level, physical activity, health conditions, and other factors, making it almost impossible to determine an exact time naltrexone will show up on a drug test.

Detection Windows for the Pill Form

The following is an estimated range of times, or detection windows, during which immediate-release versions of naltrexone can be detected by various testing methods. (Vivitrol is extended release, and can remain detectable in drug tests for months):

  • Urine: Naltrexone can be detected in the urine for 4 to 6 hours.
  • Blood: A blood test can detect naltrexone for up to 24 hours.
  • Saliva Test: A saliva test can detect naltrexone for up to 1 day
  • Hair Follicle Test: Naltrexone, like many other drugs, can be detected with a hair follicle drug test for up to 90 days.

Avoiding an Overdose

Naltrexone is in a class of medications called opiate antagonists. It works by decreasing the craving for alcohol and blocking the effects of opiate medications and illicit opioid drugs. Along with counseling and social support, naltrexone is used to help people who have stopped drinking alcohol and using street drugs continue to avoid drinking or using drugs.

If you suspect someone has taken an overdose of naltrexone, call the poison control center. If the victim has collapsed or is not breathing, call 9-1-1 or the other emergency medical number for your location.

To avoid a possible accidental overdose of naltrexone, do not take more or less of it, or take it more often, than prescribed.

Symptoms of an overdose of naltrexone include:

  • Confusion
  • Hallucinations
  • Blurred vision
  • Severe vomiting and/or diarrhea

Another serious concern with naltrexone is when a person tries to take enough opiates to get the effects despite the blocking action of the naltrexone. This can result in serious injury and even death.

If you or a loved one are struggling with substance use or addiction, contact the Substance Abuse and Mental Health Services Administration (SAMHSA) National Helpline at 1-800-662-4357 for information on support and treatment facilities in your area.

For more mental health resources, see our National Helpline Database.

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  1. Palpacuer C, Duprez R, Huneau A, et al. Pharmacologically controlled drinking in the treatment of alcohol dependence or alcohol use disorders: a systematic review with direct and network meta-analyses on nalmefene, naltrexone, acamprosate, baclofen and topiramate. Addiction. 2018;113(2):220-237. doi:10.1111/add.13974

  2. Substance Abuse and Mental Health Services Administration. Opioid Overdose Prevention TOOLKIT. Updated 2018.

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