Naltrexone is an opioid antagonist used to assist in the management of alcohol and opioid use disorders.
Naltrexone is an opioid-receptor antagonist, meaning it blocks the effects of opioids in the brain. It is primarily used to reduce cravings and prevent relapse in people who have stopped using alcohol or opioid substances. The ingredient appears in several products available in Hong Kong, such as Revia, generic Naltrexone tablets, and the combination medicine Contrave (bupropion + naltrexone).
In Hong Kong’s pharmacy market you will find Naltrexone in both single-ingredient and combination forms. Revia is a branded tablet that contains only Naltrexone, typically supplied in 50 mg strengths. The generic version, simply called Naltrexone, offers the same dosage options under different manufacturers. Contrave pairs Naltrexone with the antidepressant-type agent bupropion; this fixed-dose combo is marketed for weight-management support rather than substance-use treatment. Some pharmacies also stock a combined product listed as Bupropion + Naltrexone, which follows the same formulation as Contrave. All of these medicines are approved by Hong Kong’s Department of Health and are available by prescription only.
These uses are guided by clinical guidelines and the product’s approved labeling. The medication is intended for adults who have already achieved a period of abstinence or who are following a supervised weight-loss program.
When taken, Naltrexone binds to the brain’s opioid receptors without activating them. This “blocking” action prevents opioid substances from producing their usual euphoric effects and also reduces the reinforcing feeling that can follow alcohol consumption. Because the receptors are occupied, any opioid taken later will have little to no effect, helping the person stay away from the substance. The onset of this blocking effect is usually felt within a few hours after the dose, and the medication continues to work as long as it remains in the system.
These reactions are generally transient and do not require medical intervention unless they persist.
If any of these occur, seek emergency care right away.
For a complete list of interactions, refer to the individual medication’s product information.
Store Naltrexone tablets in a cool, dry place away from direct sunlight and out of reach of children. Typical treatment courses differ: short-term use is common for relapse prevention, while the combination product for weight management may be taken for several months under medical supervision. Always follow the specific guidance that comes with your prescription, as strengths and dosage schedules vary between products. For detailed usage, dosing, and administration, refer to your specific medication’s information.
Opioid antagonist: A substance that blocks opioid receptors, preventing opioids from producing their usual effects. Receptor blockade: The process of occupying a receptor so that other substances cannot bind to it. Off-label use: Using a medication for a condition that is not listed in its official approval.
This article offers general educational information about Naltrexone as an active substance used in various medicines. Its purpose is to help patients better understand the ingredient and the conditions it is used to treat. It is not a substitute for professional medical advice or for the specific instructions provided with individual products. Medicines containing Naltrexone may differ in formulation, strength, and directions for use. Always consult the labeling of your particular medication and follow your healthcare provider’s guidance for complete information on proper use, dosage, and safety.
