How Long Does Naltrexone Stay In Your System?

Naltrexone is used to help people stop drinking or prevent opiate drug abuse. The length of time it stays in the system depends on mode of administration? Read more on how naltrexone is metabolized here.

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Reviewed by: Dr. Dili Gonzalez, M.D. Dr. Juan Goecke, M.D.

Medications For The Treatment Of Addiction Can Help!

Alcoholism and opiate addiction affect millions of American families. However, a growing body of evidence supports  medication assisted treatment for addiction (drugs like naltrexone, methadone, or buprenorphine) in the treatment of dependence on these substances. In fact, medications best assist people in recovery when used as a part of a structured treatment and support program.

But, how long does it stay in the body? How is naltrexone metabolized exactly? And are there any side effects?

Here, we review ways that you take naltrexone and how the mode of administration affects the time it stays in your body. Then, we invite you to add or ask something new in the comments section at the end of the page. Know that when you make the effort to contact us, we try our best to provide a personal and prompt response.

Why Are People Taking Naltrexone?

Naltrexone is prescribed as a complementary therapy to appropriate psychological and behavior addiction treatment program. When use as a part of a holistic therapeutic model, it can have many benefits for people in addiction recovery from alcohol or opiate/opioid addiction. Plus, naltrexone’s low addictive liability makes it attractive as a science-based aid for long term sobriety. More specifically, naltrexone can help:

  1. Block the need and cravings for alcohol and opioids
  2. Lower the risk of relapse in recovering patients
  3. Obstruct the reward circuit from reacting to alcohol or opiate drugs in the brain
  4. People concentrate on the treatment process
  5. People work on underlying issues that trigger substance use
  6. Prevent the excessive release of dopamine in the brain
  7. Users experience pleasurable activities without drugs or alcohol

How Do You Take Naltrexone?

Before a person is given a prescription for naltrexone, it is very important that drugs or alcohol have left the body. This is why doctors check for recent alcohol or opiate drug use before you begin naltrexone dosing. There are two (2) main criteria before beginning naltrexone treatment:

1. YOU SHOULD NOT USE opiate drugs (illicit or prescription) 10-14 days before starting naltrexone.

2. YOU SHOULD NOT DRINK alcohol at least a week before taking the first dose of naltrexone.

Naltrexone For Opioids And Time In The Body

In terms of dosing, 50mg of naltrexone have the ability to block the effects of opioids for about 24 hours. Clinical studies suggest that doubling the dose will block opioid effects  for 48 hours, while 150mg of naltrexone can provide blockage for approximately 72 hours. The injectable form of naltrexone, known under the brand name Vivitrol can also be prescribed by doctors. Given as a shot once every month, it can stay in the system for about four (4) weeks, give or take a few days.

Naltrexone For Alcohol And Time In The Body

In clinical studies, the standard daily naltrexone dose for alcoholism which is 50mg a day has helped successfully support alcohol abstinence, prevented relapse and decreased alcohol consumption. This dose is active in the system for 24 hours at a time. Naltrexone injection (Vivitrol) can also be used in alcohol dependent patients, but it is administered once a month, given by a doctor or a nurse.

Peak Levels And Half Life Of Naltrexone

The peak levels and half life of naltrexone vary depending on mode of administration: oral vs. injection.

Orally administered naltrexone is almost completely (about 96%) and rapidly absorbed by the gastrointestinal (GI) tract. Peak plasma levels occur within 1 hour of dosing. The metabolites are excreted by the kidneys, while the elimination half life of naltrexone and metabolites ranges between 4 and 13 hours.

Vivitrol is an extended-release version of naltrexone, administered by intramuscular injection. After the shot of Vivitrol is given to a patient, a transient initial peak occurs about 2 hours after, and is followed by a second peak which occurs approximately 2-3 days after injection. Concentrations of naltrexone begin to slowly decline in about 2 weeks after dosing, but stay measurable for more than month. The elimination half life of injected naltrexone ranges between 5 to 10 days.

Naltrexone Drug Testing: How Long Does Naltrexone Stay In The Body?

Naltrexone is a medication with no euphoric properties and has no addictive potential. Naltrexone does not produce a high, nor does it create dependence or addiction in patients. This is why it is not included in drug testing by doctors and employers.

However, naltrexone can interfere with laboratory tests for other substances, so before having any drug test you should tell your doctor and the laboratory personnel that you are regularly receiving naltrexone therapy.

Doctors are obligated to test patients for recent alcohol or opioid dugs use before treatment is initiated.  If certain substances are mixed with naltrexone there is a possibility for uncomfortable drug interactions and adverse effects. Also, while a patient is on naltrexone, doctors should run regular tests to monitor a person’s health and functioning of internal organs (such as the heart, liver, and kidneys).

Problems With Naltrexone?

Patients who are taking naltrexone can experience some unexpected and unwanted effects. However, before initiating treatment, your doctor should inform you about the possible  side effects of naltrexone.

It is important to call your doctor if any unusual or persistent effects from the medication occur. Note that naltrexone side effects shouldn’t be ignored and should be brought to doctor’s attention as soon as possible. They include:

  • Abdominal pain
  • Anxiety
  • Chest pain
  • Constipation
  • Diarrhea
  • Drowsiness
  • Fluctuation in energy levels
  • Headaches
  • Loss of appetite
  • Muscle and joint aches
  • Nausea
  • Tiredness
  • Problems sleeping or insomnia
  • Restlessness
  • Skin rashes

Naltrexone In The System Questions

We hope we managed to answer your questions about naltrexone and its use, mechanism of action, and workings in the body. We can answer further questions or uncertainties if you post them in the comments section below. We try to provide a personal and prompt response to all legitimate inquiries.

Reference Sources: PubChem: Naltrexone
MedlinePlus: Naltrexone
NIDA: Naltrexone-An Antagonist Therapy for Heroin Addiction
SAMHSA: Naltrexone
NIDA: Narcotic Antagonists: Naltrexone (Pharmacochemisty and sustained-release preparations)
SAMHSA: Addiction Treatment Forum: Evidence for the Efficacy of Naltrexone in the Treatment of Alcohol Dependence (Alcoholism)
About the author
Lee Weber is a published author, medical writer, and woman in long-term recovery from addiction. Her latest book, The Definitive Guide to Addiction Interventions is set to reach university bookstores in early 2019.
Medical Reviewers
Dr. Dili Gonzalez, M.D. is a general surgeon practicing women's focused medici...
Dr. Goecke is a medical doctor and general surgeon with personal experience of...

All of the information on this page has been reviewed and verified by a licensed medical professional.


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  1. I took the pill in the morning and my anxiety went thru the roof! Restless, vomiting, chills, hot flashes, headache, stomach ache, diarrhea, fussy head, confusion. I had some drinks but didn’t want them but was worried about alcohol withdrawals. My doctor prescribed 50 mg. I’m thinking too much for me? Cause it’s 34 hours later and I’m still waiting for it to where off…. also was wondering how many days or hours after to take a Xanax for my anxiety and to sleep since I haven’t at all! Literally at all? any comments would be appreciated. All my doc office told me was to take a walk or a shower…

    1. Hi Melanie. It seams that what you experienced were side effects of the medication. Naltrexone side effects shouldn’t be ignored, so call you doctor and explain him/her what are you experiencing. Do not take any medications on your own with consulting with your doctor first.

  2. If I’m receiving my first vivitrol shot tomorrow, should I take my dose of naltrexone tonight or skip it since I’m getting the shot tomorrow?

  3. The Purpose of Naltrexone/Vivatral is to Reduce/Block the release of Dopamine/Feel Good Endorphins at the Wrong Time due to Abuse of Alcohol and or Opioids.
    If Not Willin to Heal then why take the Medication?
    Are You Serious or Still Abusin Your Mind and Body?
    Grow Up Folks.. It’s a Blessin to have this Medicine available

  4. Ruthann, a 50mg dose of Naltrexone lasts around 24 hours, but its metabolite lasts around 36. In my experience the metabolite life makes it worthless to take any pain medication for at least 36 hours on a single 50mg dose.

  5. Hi, I am trying to figure out how many days after taking naltrexone can I take a pain pill and it actually work for my pain.

  6. My husband takes SUBOXON everyday he was out and took one of these 50 mg pills about 10 mins later he said he felt like he was on fire and had chill at the same time ,he took it about 10 pm last night and is still aggitated and has every side effect almost name in the drugs description.. it’s. Been 14 hours can he take his Suboxone now or should he wait and if so how long… Will his suboxone help with the side effects of this drug

  7. My son was given a monthly shot of Neltrexon on last July. He is convinced that it is still affecting his ability to enjoy alcohol or meth.. Is it possible that this drug could still be affecting his ability to enjoy alcohol or meth? I really need to let him know the facts about this so he doesn’t obsess about it thanks

  8. Hi. My daughter is addicted to heroin, has no insurance and can’t afford the vivitrol shot.The information I got from your article seems to be that the oral tablets take effect right away within 1 hour of their first dose, thus blocking the effect of the opiod? If not, how long does she has to take these tablets, lowest dose possible, before they start blocking the effects of opiods?

  9. My doc started me on 25 mg of Naltrexone; then wanted me to increase dose after 7 days to 50 mg. She’s prescribing it “off label” to take in combination with Wellbutrin which is supposedly going to “make Contravene”. (For binging control). I took the 25 mg for 7 days with no effects whatsoever. No reduced binge cravings and no side effects. Then on day 8 I took the same dose and became violently ill. Vomiting, nausea, headache. Day 9 was the same. Day 10 I stopped taking it. Here I am at Day 11 (still not taking it) and I feel better but still nauseous. I thought Naltrexone went out of the system quickly? How long before this gets completely out of my system? I’ve never been this miserable.

  10. I have been taking naltrexone for three months, I recently fell and I think I cracked rib. It is very painful and I would like to take pain medication in order to sleep at night. I’m not taking naltrexone for treatment of opiate addiction nor alcohol addiction. It was prescribed for weight loss in Confide combined with another drug Butrolful (sp) When can I take an opiate safely. The pain has been going on for two weeks and does not seem to improve. I am positive it is caused from the fall because it started immediately.

    1. Hi Jack. I suggest you discuss this issue with your doctor in order to be 100% sure if the pain is caused from the fall or not.

  11. Just wanted to warn everyone as to why its so important to wait 10-14 days after stopping opiates or opioids, before taking naltrexone.

    I have been off suboxone (buprenorphine) for 7 days and took 50mg naltrexone today. Within an hour all opioids (buprenorphine and or its metabolites) were blocked in my brain. It was total and nearly instant withdrawal. It feels like actual hell right now.

    I have to wait another 15 hours, roughly, until the naltrexone has worn off and the lingering suboxone in my body can reattach and take this massive withdrawal away. It’s the worst feeling I’ve ever experienced.

  12. i’ve been on naltraxone for 3 months with a 2 week window in which i drank. then started it again in sept 4th and have used it everyday since. i took it today but would like to have a drink tomorrow. will i get sick if i don’t take it tomorrow since i took it today?


  13. i take 50 mg of naltraxone every day … tomororow is my birthday and i plan on not taking it tomorrow. can i have a drink that night?

  14. I take 50mg naltrexone- gotten from Indian pharmacy- for every 8-10 hours of drinking session. Is this right. I used to take only 1 pill when I started. I am drinker of a bottle of 70cl a day for over 30 years. If I smoke hash I do not need to drink. It can act as a substitute. My doctor tells me this is better. My liver is ok as I drink only brandy or whiskey with lots of water. It’s been 5 months now with no reduction that I notice. What’s the problem ? Shall I continue? Someone told me I should take 1 pill for every 8 hours session. This I am doing for last 2 months. 1st 4 months I took a pill a day.

  15. I just started taking the first two times a half of a 50mg pill third day a whole pill and am sick to my stomach ESP after a cigarette but have been sick since starting when can I expect to feel better how long is this going to b in me

  16. I have been getting injections for. 4 months now and was taking pull form for 2 months.I am an alcoholic.I have Chronic pain in my back and hip.I am going to Pain Clinic in a week.I got my last injection on May 1st.How long should I wait before taking my pain meds which are 7,5/325 hydro?I am only using them for short term use until I get injections on my back.

  17. I have a friend that is on the injection of Vivitrol. His last shot was the first of March. He missed his shot for today – April 1st – and is scheduled to go visit friends out of state that he used to drink and drug with. He will have been off the Vivitrol for one week while gone. Will he be able to drink? Is the Vivitrol still in his system?

  18. I have been prescribed 50 mg. naltrexone daily (to be taken before bedtime). I had gastric bypass surgery 10 years ago. Do you think my body is absorbing and getting the full effects of the drug? I’ve been on it for three weeks and feel nothing different.

  19. I had the visit roll shot Jan 29th, I have a bottle of norco I have been taking a couple a day and it does not relieve my pain and I get no high. It is feb 18th, when will I feel the effect of my norco?

  20. Hi I have crohn’s diesease and take remicade infustions every six week, have no additions.
    My yoga instructor recommended naltrexone for a chronic arthritic pain I live with from the inflammation related to crohn’s. Have you any information on this drug being used for pain management?

  21. Is it possible to get liver failure if one continues to drink alcohol while. ,taking naltrexone? The doctor knows that I
    am an alcoholic with little desire to quit but he wants me to keep taking it

  22. I have been taking vivitrol for 2 months for alcohol abuse (no problem with opioids) I’m having surgery a month and a week after last shot of vivitrol, will I still get sick with the pain meds they give me? Thanks.

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