Naltrexone is a medication that blocks opioid receptors without switching them on. Doctors use it to treat opioid addiction and problem drinking. Because it takes the reward out of using, it can quiet the pull toward a substance while other recovery work goes on. It is not a sedative, and it does not cause dependence.
How Naltrexone Works For Addiction
Opioids produce a high by switching on receptors in the brain. Naltrexone sits on those same receptors and holds them shut. If someone uses heroin, fentanyl, or a prescription opioid while naltrexone is active, the expected high never arrives. Take the reward away often enough and the habit loses some of its grip.
For alcohol use disorder, the effect is subtler. Naltrexone dampens the dopamine surge that follows a drink, so alcohol feels less rewarding and the urge to keep pouring eases. Two forms exist. Oral tablets are taken daily, while Vivitrol, the extended-release injection, is given once a month. Both create the same receptor blockade. A tablet starts blocking within about an hour, though the drop in cravings usually builds over days to weeks.
What To Know Before Starting Naltrexone
Timing matters more than anything else here. A person has to be fully off opioids before the first dose. Otherwise naltrexone can trigger sudden, severe withdrawal: body aches, sweating, anxiety, nausea, and a racing heart. Clinicians confirm that window with an exam, urine screening, or a challenge test. This step is never optional.
Tolerance also falls while the medication is in use. Returning to an old dose after stopping carries a high risk of fatal overdose, so plan any stop with a doctor. Most side effects are mild, such as nausea, headache, dizziness, or soreness at the injection site. Liver injury is rare, though baseline liver testing is standard. Naltrexone can be taken safely for years. On its own, though, it does not touch the habits and pressures underneath an addiction.
