Naltrexone: What It Does, How to Use It, and Safety Tips

Naltrexone is an opioid blocker that also lowers alcohol cravings. Doctors use it to help people stay off opioids after detox and to cut drinking in people with alcohol use disorder. It comes as a daily pill (usually 50 mg) and a monthly injection (Vivitrol). This page gives straight talk on dosing, risks, and safe ways to get it—especially if you’re thinking about buying online.

How naltrexone works and who it helps

It fits on opioid receptors and blocks the effects of opioid drugs. That means if someone takes heroin or oxycodone while on naltrexone, they won’t feel the usual high. For alcohol, it seems to reduce the reward drinking gives you, which lowers cravings and helps cut heavy drinking days. It’s not a magic fix—combine it with counseling or support for best results.

Standard oral dose: 50 mg once daily. Injectable dose: 380 mg once a month. Some clinicians use low-dose naltrexone (LDN) off-label for pain or autoimmune issues at 1.5–4.5 mg nightly, but that’s experimental and should be supervised by a doctor.

Safety, side effects, and precautions

Big rule: don’t take naltrexone if you’re physically dependent on opioids or using opioid pain meds. It can trigger sudden, severe withdrawal. Before starting, you’ll usually need to be opioid-free for 7–14 days and may need a supervised test dose.

Common side effects are nausea, headache, fatigue, dizziness, and sleep problems. A serious risk is liver injury at high doses, so doctors often check liver tests (LFTs) before starting and during treatment if doses are high or symptoms appear. Tell your clinician if you drink heavily, have hepatitis, or take other liver-risk drugs.

Interactions to watch for: opioid pain relievers (blocked), methadone and some buprenorphine regimens (can cause withdrawal), and other meds that stress the liver. If you need pain relief while on naltrexone, your doctor will plan a safe alternative.

If you miss a dose, take it when you remember unless it’s almost time for the next dose—don’t double up. If you plan surgery or need opioid pain control, let your care team know; naltrexone can interfere with pain management for days after stopping.

Thinking about buying online? Never buy naltrexone without a prescription. Look for pharmacies that require a valid Rx, show clear contact details, and have verifiable reviews. Avoid sites with prices that seem too low, no phone number, or no licensed pharmacist access. When in doubt, use a local or well-known national pharmacy—especially for injections, which need a clinic or trained provider.

Questions about whether naltrexone fits your situation? Talk to a clinician who knows addiction or liver care. They’ll check your history, order any needed tests, and help you pick the safest option.