Naltrexone Dosage: Dosing Forms And Administration

Last Updated: June 26, 2020

Authored by Olivier George, Ph.D.

Reviewed by Michael Espelin APRN

Choosing a correct Vivitrol dose is crucial for successful alcohol and opioid withdrawal management. The dosages differ depending on what the medication is intended to treat. It is, therefore, important to learn how naltrexone dosing is determined and in what forms it is available in addition to discussing the treatment plan with a medical professional.

Naltrexone Ways Of Administration


The most common form of the medicine is a naltrexone pill. Brands that produce oral naltrexone are ReVia and Depade. Pills are the most suitable for the majority of patients because of the simplicity of their use. However, the necessity to take a 50 mg dose of naltrexone daily for weeks can be a burden to some patients.


Fortunately, the medication is also available as a naltrexone injection. A single 380 mg dose of the drug has to be delivered once a month intramuscularly. The injectable naltrexone is produced under the brand name Vivitrol. The main drawbacks of Vivitrol are the necessity to have some medical expertise to perform an injection and potential Vivitrol injection site inflammation.

Intramuscular naltrexone injection.


Another special form of the medicine is LDN naltrexone. It has a larger variety of formulations and comes as oral liquid, capsules, sublingual drops, cream, and tablets. Low-dose naltrexone for pain shows promise as a particularly well-tolerated and effective remedy that can be used daily. Naltrexone 1.5 mg dose reduces inflammation and acts independently from the medicine’s influence on opioid receptors.

Naltrexone Dosage For Opioid Dependence

Naltrexone for opiate withdrawal can be taken orally or administered as an intramuscular injection. The doses differ depending on the way of administration, and the patient’s individual needs and health condition.


For relapse prevention. As a part of addiction treatment programs, Naltrexone 25 mg dose is administered once at the beginning of treatment. Subsequently, 50 mg doses of the medication are taken daily. In some cases, the dosage might be increased to 100 mg daily.

For rapid detoxification. Rapid detoxification is an option preferred by some patients that enables them to avoid withdrawal symptoms. Naltrexone 50 mg doses are sometimes used during rapid detox. The practice, however, presents significant health risks and can only be done in a clinical setting.


Vivitrol injection is given once every 4 weeks or once a month. A dose of 380 mg is normally used. The manufacturer notes that only the original needles can be used for the injection, and the patient’s body size must be taken into consideration when choosing the length of the needle.

Naltrexone Dosage For Alcohol Dependence

Naltrexone for alcohol withdrawal via the Sinclair method is one of the main uses of the medication. The method itself leads a person to gradually reduce the amount of alcohol they drink by administering an adjustable dose of naltrexone.


Naltrexone is mainly taken as a pill to fight alcohol dependence. A standard dose of 50 mg reduces the pleasurable effects of alcohol and, hence, makes an individual less likely to engage in drinking. During the treatment, the person has to take a dose of the medication either daily or before any alcohol consumption. This medication doesn’t interact adversely with alcohol, and it is not addictive.


A Vivitrol dose of 380 mg is injected once every four weeks. For this reason, it is considered slightly less convenient for alcohol dependence treatment. In addition, some patients wonder whether they can get Vivitrol in pill form. Vivitrol is only available for injections. An alternative to a nonexistent Vivitrol pill is ReVia.

Naltrexone Dosage For Weight Loss

Although it is not one of its officially approved applications, low-dose naltrexone can be used for weight loss. Naltrexone weight loss dosage was found to be the most beneficial at 32 mg. However, to achieve the best results, naltrexone has to be combined with bupropion. A sustained-release combination pill that contains a 32 mg dose of naltrexone and a 360 dose of bupropion is approved for obesity treatment. The standard dose of naltrexone 50 mg for weight loss might still be effective; however, its action will be affected by many factors such as the person’s weight, height, age, and individual biological characteristics.

naltrexone dosage for weight loss

Missing A Dose

Missing a naltrexone dose should be avoided whenever possible. If a patient misses a dose, they should take it as soon as they remember. However, if it is soon time for the next dose, the individual should skip the missed one and stick to the schedule. It is crucial not to compensate for the missed dose since it can lead to overdose and severe side effects.

Naltrexone Overdose Symptoms And Treatment

Patients receiving naltrexone treatment are at an increased risk of these two issues: Vivitrol overdose and overdose on the person’s substance of abuse.

How Can An Overdose Occur?

Naltrexone overdose might happen when a person takes a larger dose of the medication than they were prescribed. This may be accidental or result from attempting getting high on Vivitrol.

Signs And Symptoms Of An Overdose

The main symptoms of an overdose on a drug are naltrexone nausea, dizziness, stomach pain, and seizures. Other potential and more long-standing effects include the return or emergence of opioid withdrawal symptoms and liver damage. Vivitrol overdose is a serious issue, and a patient should contact a medical professional as soon as possible after detecting the signs.

Treatment Of An Overdose

Vivitrol overdose is countered by different medical procedures depending on the types of drugs present in a person’s system apart from the medicine. Activated charcoal and laxatives may be used to slow down the absorption of the medication and to flush it out of the person’s system. In extreme cases, stomach pumping and hemodialysis (blood washing) might be required. In addition, an antidote can be administered to prevent naltrexone overdose from leading to long-lasting severe effects.

naltrexone overdose

Naltrexone LD50

LD means “Lethal Dose,” and LD50 describes Vivitrol dosage at which 50% of a group of test animals dies. This parameter is useful for assessment of the acute toxicity of a substance. There are no human studies on naltrexone LD50. In animal testing, the drug LD50 is:

  • for mouse (oral) – between 1.1 and 1.55 g/kg;
  • for mouse (intravenous) – 180 mg/kg;
  • for rats (oral) – 1.45 g/kg;
  • for monkeys – 3 g/kg.

Awareness Of Dosing Is Important

ReVia and Depade are the most suitable for the majority of patients since they come as pills and don’t require a person to possess any medical skills. The drug injection is mainly used in the rehab facilities. Vivitrol dosing varies for each of the disorders that it can be used to treat. While the medication is effective at fighting physical dependence, it does not help tackle addiction as such. For this reason, it is strongly advised to use Vivitrol as a part of a complex rehab program to achieve long-standing results.

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Published on: June 7th, 2019

Updated on: June 26th, 2020

About Author

Olivier George, Ph.D.

Olivier George is a medical writer and head manager of the rehab center in California. He spends a lot of time in collecting and analyzing the traditional approaches for substance abuse treatment and assessing their efficiency.

Medically Reviewed by

Michael Espelin APRN

8 years of nursing experience in wide variety of behavioral and addition settings that include adult inpatient and outpatient mental health services with substance use disorders, and geriatric long-term care and hospice care.  He has a particular interest in psychopharmacology, nutritional psychiatry, and alternative treatment options involving particular vitamins, dietary supplements, and administering auricular acupuncture.


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