Description

Revia (naltrexone)

Before the first tablet, you’ll need a urine test. Not as a formality — because if opioids are still clearing your system when naltrexone arrives, precipitated withdrawal begins within minutes of the first dose. Faster and harder than natural withdrawal. The minimum wait is 7 to 10 days after short-acting opioids like heroin. After methadone, the FDA guidance extends to up to two weeks, because methadone accumulates in tissue and clears more slowly than how you feel would suggest. These aren’t conservative estimates padded for liability. They’re the clinical floor.

Once that timing is cleared, something specific happens when you take the drug: nothing. Naltrexone occupies opioid receptors completely and sits there inertly. An opioid taken on top of it finds no available binding sites. No high. No relief. No signal. The reward doesn’t fire.

That absence is the mechanism.

For alcohol

The same blocking logic applies to alcohol, though one step removed. Alcohol triggers a partial opioid response in the brain — that first-drink relaxation runs through the same receptor system naltrexone occupies. Drinking on ReVia isn’t aversive or painful, but the reward signal weakens. The urge to keep going settles. For a substantial portion of people, that shift is enough to change behavior over time.

Dosing and pharmacokinetics

50 mg once daily. Once-daily dosing works because naltrexone converts in the liver to an active metabolite — 6-β-naltrexol — with a half-life of roughly 13 hours. The parent compound itself clears faster, around 4 hours, but the metabolite carries the clinical effect through the day.

Packs come in 10 to 90 tablets. Most prescribers start with a shorter supply to confirm tolerability before committing to longer courses.

Side effects

Common in the first two weeks: insomnia, anxiety, nausea, fatigue, headaches, muscle cramps. These settle for most people. For some they don’t, and that’s worth knowing before you start rather than treating it as evidence the drug isn’t working.

Sexual dysfunction appears in the rare category on most prescribing labels. It shows up often enough that burying it in a list doesn’t serve anyone. If it develops, raise it with your prescriber early rather than waiting for it to resolve on its own.

Less common: appetite changes, digestive issues, allergic skin reactions. A rash after starting is a reason to stop and call.

Liver, pregnancy, and surgery

Naltrexone is hepatically metabolized. Existing liver disease doesn’t automatically rule it out, but baseline function tests before starting and regular monitoring during are standard practice for a reason. Hepatitis or cirrhosis needs a more detailed conversation than a routine initiation.

Pregnancy data is absent — meaning unknown, not probably fine. No adequate studies have been conducted. If pregnancy is possible or planned, the conversation happens before the first dose.

One more thing that matters operationally: any opioid given to you during surgery, an emergency, or a dental procedure will be blocked while naltrexone is active. Every clinician who might treat you needs to know you’re on this drug before they reach for pain management. Not as background — as something that changes their options.

Who it actually helps

ReVia is a maintenance tool. The clinical evidence is clearest for people who’ve already completed an initial detox or treatment program and want pharmacological support during the months that follow. The strongest outcomes come when it’s paired with behavioral therapy or group support — not because the drug is weak, but because physical dependency and the circumstances around it aren’t the same problem.

Naltrexone removes one specific pull toward relapse. What it doesn’t do is address the rest.