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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