How Long Does Naltrexone Take To Kick In?

Medically Reviewed by Johnelle Smith, M.D. on April 19, 2022

Naltrexone is a prescribed drug used to treat alcohol use disorder and opiate addiction. The duration of effects will depend on the form taken and other personal factors. It is commonly taken as part of a medication-assisted treatment program.

How Long Does It Take For Naltrexone To Kick In?

Naltrexone is a prescription medication that can begin to take effect within one to two hours after taking a standard prescribed dose. How quickly it kicks in largely depends on the form taken.

How long naltrexone takes to kick in:

  • Naltrexone injection: About two hours after injection.
  • Naltrexone pill: About one hour after use.

Naltrexone is an opioid antagonist prescribed for the treatment of alcohol use disorder (alcohol dependence) and opioid addiction. Its effects kick in shortly after the first dose.

Learn more about taking Naltrexone for opioid and alcohol addiction

How Many Hours Does Naltrexone Work?

Naltrexone is prescribed in the form of a pill or extended-release injection. In pill form, naltrexone effects can last between 24 to 48 hours, depending on the dose taken.

Extended-release naltrexone injections (Vivitrol) for opioid addiction produce effects slowly over the course of a one-month period. How long effects last may vary according to some factors.

Factors that can affect the duration of effects include:

  • age: Older adults metabolize drugs at a slower rate, which may cause the drug to stay in a person’s system for longer.
  • metabolic rate: A slow rate of metabolism can cause naltrexone to stay in the body for longer and thus prolong its effects.
  • use of other drugs: Certain medications can interact with naltrexone and cause it to metabolize at a slower rate or reduce its effects.
  • body mass: Body weight can affect the rate of drug absorption and how long it takes for the body to fully process drugs like naltrexone.

Naltrexone is generally taken either once a day, or three times a week in pill form. The injectable form of naltrexone is administered once a month by a licensed healthcare provider.

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What To Know About The Effects Of Naltrexone

Naltrexone should be taken exactly as prescribed by the prescribing physician.

People taking naltrexone should avoid drinking alcohol, using illicit drugs, or taking medications known to have negative drug interactions with naltrexone.

Taking naltrexone in ways other than directed could result in:

  • reduced drug effects
  • drug toxicity
  • accidental overdose
  • other adverse reactions

Certain drugs may enhance or reduce the effects of naltrexone. If you’re taking other medication, be sure to tell your doctor before beginning naltrexone treatment.

Call Today To Find Naltrexone Treatment

Naltrexone is a medication that is commonly prescribed for alcohol dependence and opioid addiction as a medication-assisted treatment (MAT) option.

Naltrexone can help to:

  • reduce cravings for alcohol and opioids
  • reduce alcohol consumption
  • help people maintain sobriety
  • block the euphoric effects of opioid and alcohol

Call our helpline today to learn more about naltrexone treatment and how to find addiction treatment options near you.

This page does not provide medical advice. See more

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Medically Reviewed by
Johnelle Smith, M.D. on April 19, 2022
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