Naltrexone and buprenorphine are both FDA-approved medications for opioid use disorder, but they work in fundamentally different ways. Buprenorphine is a partial opioid agonist that reduces withdrawal and cravings. Naltrexone is an opioid antagonist that blocks opioid receptors and does not treat active opioid withdrawal.
How does buprenorphine work?
Buprenorphine partially activates opioid receptors while binding to them very strongly. This can reduce withdrawal symptoms and cravings and help stabilize opioid use disorder treatment.
How does naltrexone work?
Naltrexone blocks opioid receptors. It does not produce opioid effects, and the extended-release injectable form is FDA-approved for opioid use disorder. Because it blocks opioids, a person must be opioid-free before starting it to avoid precipitated withdrawal.
What is the biggest practical difference between the two?
Buprenorphine can usually be started during opioid withdrawal, while naltrexone requires a period of opioid abstinence first. SAMHSA states that extended-release naltrexone generally requires at least 7 days after the last use of short-acting opioids and 10 to 14 days after long-acting opioids, although the exact clinical plan should be individualized.
Does either medication cause physical dependence?
Buprenorphine can cause physical dependence because it is an opioid medication, so stopping it abruptly can cause withdrawal. Naltrexone is not an opioid and does not cause opioid dependence.
Which medication is better for cravings?
Both can help reduce relapse risk, but they work differently. Buprenorphine directly reduces withdrawal and cravings. Naltrexone blocks opioid effects and may reduce cravings for some patients. Treatment choice should reflect the person’s goals, prior treatment response, access to care, ability to complete an opioid-free period, and medical history.
What happens if someone uses opioids while taking naltrexone?
Naltrexone blocks opioid effects. Trying to overcome that blockade by taking large amounts of opioids can be dangerous. After naltrexone is stopped, opioid tolerance may be lower, which can increase overdose risk if opioid use resumes.
Can someone switch from buprenorphine to naltrexone?
Yes, but the person must complete an opioid-free interval before starting naltrexone. Because buprenorphine is long acting, the transition should be medically planned rather than attempted independently.
Which medication is easier to access?
Buprenorphine can be prescribed by qualified clinicians in many outpatient settings. Extended-release naltrexone can also be prescribed and administered by licensed practitioners, but it requires the patient to be opioid-free before initiation.
Trinity Behavioral Health provides information about residential addiction treatment. This article does not state that Trinity provides either medication; current medication options should be verified directly with the treatment team.
Frequently asked questions
Is naltrexone an opioid?
No. It is an opioid antagonist.
Can buprenorphine be started while someone is still using opioids?
Standard induction usually begins after sufficient withdrawal develops. Low-dose initiation may overlap with full opioid agonists under medical supervision.
Can naltrexone trigger withdrawal?
Yes. If opioids are still in the body, naltrexone can precipitate withdrawal.
Is oral naltrexone approved for opioid use disorder?
The extended-release injectable formulation is the FDA-approved form commonly used for OUD; oral naltrexone is used for alcohol use disorder and has different adherence considerations.
Sources
This article is general educational information and does not replace individualized medical advice.