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.
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.
Addiction Resource aims to provide only the most current, accurate information in regards to addiction and addiction treatment, which means we only reference the most credible sources available.
These include peer-reviewed journals, government entities and academic institutions, and leaders in addiction healthcare and advocacy. Learn more about how we safeguard our content by viewing our editorial policy.
- National Alliance on Mental Illness — Mental Health Medications: Naltrexone
https://www.nami.org/About-Mental-Illness/Treatments/Mental-Health-Medications/Types-of-Medication/Naltrexone-(ReVia) - Substance Abuse and Mental Health Services Administration (SAMHSA) — Naltrexone
https://www.samhsa.gov/medication-assisted-treatment/medications-counseling-related-conditions/naltrexone
