When comparing naltrexone vs Suboxone, the main difference is that Suboxone can treat withdrawal and cravings during active transition from opioids, while naltrexone requires an opioid-free period before it can be started. Suboxone (buprenorphine + naloxone) partially activates opioid receptors — reducing withdrawal and cravings. Naltrexone is an opioid antagonist — it blocks typical opioid effects at usual doses. Both are evidence-based for opioid use disorder. The right one depends on where you are in your recovery and how you start.
How does each medication work?
Suboxone contains buprenorphine, a partial opioid agonist. It binds to mu-opioid receptors and activates them — but only partially, with a ceiling effect that limits euphoria and respiratory depression. Naloxone is included to deter injection misuse.
Naltrexone is an opioid antagonist. It binds to the same mu-opioid receptors but does not activate them — it blocks typical opioid effects at usual doses. The blockade is not a safety guarantee. Trying to override naltrexone with large opioid doses can cause overdose, especially as naltrexone wears off, after a missed dose, or after stopping treatment. Naltrexone is sold as a daily pill (ReVia) or as a monthly injection (Vivitrol).
When is Suboxone the better fit?
Suboxone is generally the better choice when:
- You are currently using opioids and need to start treatment quickly
- Withdrawal is the immediate barrier — Suboxone treats it directly
- You want a treatment you can start the same day, often by telehealth
- You have not been able to stop opioids long enough for a naltrexone induction
Suboxone has the largest evidence base for reducing overdose deaths and improving treatment retention in opioid use disorder.
When is naltrexone the better fit?
Naltrexone may be the better choice when:
- You have been opioid-free long enough that naltrexone won't precipitate withdrawal — typically about a week or more, longer for long-acting opioids, individualized by your physician
- You prefer a non-opioid medication
- The monthly Vivitrol injection fits your situation better than daily dosing
- You have a clear, supportive recovery environment
The catch: starting naltrexone too soon after opioids causes precipitated withdrawal — sudden, intense, and difficult. Most patients cannot make the gap on their own without medical support.
How is each medication started?
| Step | Suboxone | Naltrexone |
|---|---|---|
| Time off opioids first | Varies. For short-acting opioids like heroin or oxycodone, often around 12–24 hours of mild withdrawal first. For fentanyl, the wait is typically longer and less predictable — sometimes much longer — because fentanyl behaves differently in the body. A low-dose induction (microinduction) can avoid the wait entirely. The right timing for any patient is determined clinically. | Usually requires at least 7–10 opioid-free days after short-acting opioids per Vivitrol labeling. After methadone, buprenorphine, or other long-acting opioids, the vulnerable period can be longer — often up to about 2 weeks. The exact timing is clinical, and a naloxone challenge or supervised induction may be used in some settings. Starting too soon causes precipitated withdrawal. |
| Risk if started too early | Precipitated withdrawal — managed clinically | Precipitated withdrawal — severe; few options once started |
| Same-day start | Common | Rare without medical detox first |
| Telehealth availability | Available by telehealth where clinically appropriate and legally permitted | The pill can sometimes be prescribed by telehealth; injection requires an in-person visit |
Which one is more effective?
Both are evidence-based. Most clinical guidelines — including those from SAMHSA and ASAM — rate buprenorphine and methadone as having the strongest evidence for reducing overdose deaths. Naltrexone is effective for the patients who can successfully start it, but the induction barrier means fewer patients reach a stable maintenance phase. In the X:BOT trial, extended-release naltrexone was harder to initiate than buprenorphine-naloxone. Among patients who were successfully started on either medication, outcomes were similar over the study period.
Methadone is another first-line MOUD option and may be the better clinical fit for some patients — especially when opioid tolerance is high, prior buprenorphine starts have failed, pregnancy is involved, or a structured opioid treatment program is needed. SAMHSA identifies buprenorphine, methadone, and naltrexone as MOUD options; buprenorphine or methadone are specifically identified as treatments of choice during pregnancy.
The most effective medication is usually the one a patient can actually start, stay on, and tolerate.
Can you switch between them?
Yes, in either direction — with medical supervision. Going from naltrexone to Suboxone is straightforward (you stop the antagonist, then start buprenorphine). Going from Suboxone to naltrexone is harder — it requires a buprenorphine taper followed by an opioid-free interval before extended-release naltrexone can be started. The exact wait is individualized: typical published intervals range from about a week (after a short-acting opioid taper) to roughly two weeks (after methadone or buprenorphine), but the right interval for any specific patient depends on what was being used, the dose, individual metabolism, and other clinical factors. Some specialty programs use accelerated low-dose-naltrexone protocols, which can shorten the wait. Your physician determines the right approach. Source: SAMHSA TIP 63.
Are naloxone and naltrexone the same?
No. Naloxone is a short-acting opioid antagonist used mainly for overdose reversal and as part of buprenorphine/naloxone products like Suboxone. Naltrexone is a longer-acting opioid antagonist used after detoxification to help prevent return to opioid use, or to treat alcohol use disorder.
