Naltrexone is FDA-approved for alcohol and opioid use disorder; low-dose use is a compounded, provider-only decision.
Naltrexone is FDA-approved at standard doses to help treat alcohol use disorder and to help prevent relapse to opioid use after detoxification. It works by blocking opioid receptors in the brain, which reduces the rewarding effects of alcohol and opioids. Low-dose naltrexone refers to compounded formulations at doses well below the FDA-approved strength; this is not an FDA-approved use, and any decision to prescribe it is made solely by a licensed provider based on individual clinical judgment.
## How naltrexone works
Naltrexone is an opioid receptor antagonist, meaning it binds to opioid receptors in the brain without activating them, blocking the effects of opioids and reducing the reinforcing effects of alcohol. At the FDA-approved dose, this mechanism supports its role in treatment programs for alcohol use disorder and in relapse prevention for opioid use disorder after a person has completed detoxification.
## FDA-approved uses
According to the FDA-approved label, naltrexone is indicated for:
- Treatment of alcohol dependence, as part of a comprehensive management program that includes psychosocial support - Blockade of the effects of exogenously administered opioids, used for relapse prevention following opioid detoxification
Naltrexone is available as an oral tablet and as an extended-release injectable suspension, both used at doses established in the FDA-approved labeling. Before starting naltrexone for opioid use disorder, patients must be opioid-free for a period determined by their provider to avoid precipitating withdrawal.
## What low-dose naltrexone is
Low-dose naltrexone refers to compounded capsules or liquid formulated at a fraction of the FDA-approved dose. Compounded medications are prepared by a pharmacy for an individual patient based on a provider's prescription, but they are not FDA-approved products, meaning the FDA has not evaluated them for safety or effectiveness at that dose or for that purpose. Whether to prescribe a compounded formulation is a decision made entirely by a licensed provider, based on their independent clinical judgment for an individual patient, and is not something Get It Prescribed can offer as a standard, guaranteed treatment path.
## Formulation overview
| Formulation | Status | Typical use | |---|---|---| | Naltrexone tablet (standard dose) | FDA-approved | Alcohol use disorder | | Naltrexone extended-release injection (standard dose) | FDA-approved | Opioid use disorder relapse prevention | | Low-dose compounded naltrexone | Not FDA-approved | Individual provider decision only |
## Safety and monitoring
At FDA-approved doses, naltrexone carries a boxed warning regarding the risk of hepatocellular injury, and liver function is typically monitored before and during treatment. Patients must not have opioids in their system when starting naltrexone because it can precipitate acute withdrawal. Anyone considering naltrexone in any form should disclose their full medical history, including liver disease and any recent opioid use, to their provider.
## How provider-guided access works
A licensed provider will take a full history, including current and past substance use and liver health, before determining whether standard-dose naltrexone is appropriate for an FDA-approved indication. If a compounded low-dose formulation is being considered for any reason, that decision rests with the individual provider based on their clinical assessment. You can read about how visits are structured on the [how it works](/how-it-works) page, and review [pricing](/pricing) and [availability](/availability) by state.
## Related questions
### Is low-dose naltrexone FDA-approved? No. The FDA has approved naltrexone at standard doses for alcohol use disorder and for relapse prevention in opioid use disorder. Low-dose compounded formulations are not FDA-approved, and any prescribing decision for a compounded dose is made individually by a licensed provider.
### Can I take naltrexone if I am currently using opioids? No. Naltrexone can precipitate sudden and severe withdrawal symptoms in someone with opioids in their system, so patients must be opioid-free for a period determined by their provider before starting treatment. Tell your provider about any recent opioid use, including prescription pain medication, before starting naltrexone.
### Does naltrexone require liver monitoring? Standard-dose naltrexone carries an FDA boxed warning about the risk of liver injury at higher doses, and providers typically check liver function before starting treatment and periodically during use. Report any symptoms of liver problems, such as unusual fatigue or yellowing of the skin or eyes, to your provider promptly.
### How is naltrexone different from methadone or buprenorphine? Naltrexone blocks opioid receptors without activating them, while methadone and buprenorphine are used differently in opioid use disorder treatment and work through different receptor mechanisms. The right medication depends on an individual's treatment history and clinical needs, which a licensed provider is best positioned to assess.
## Sources - [DailyMed search: naltrexone](https://dailymed.nlm.nih.gov/dailymed/search.cfm?query=naltrexone) — FDA-approved prescribing information, including boxed warning and approved indications. - [MedlinePlus: Naltrexone](https://medlineplus.gov/druginfo/meds/a685041.html) — consumer information on approved uses and precautions. - [NCBI Bookshelf: Naltrexone](https://www.ncbi.nlm.nih.gov/books/NBK551620/) — clinical reference on naltrexone pharmacology and use in substance use disorders.