Naltrexone
Naltrexone blocks opioid receptors and is used alongside behavioural and clinical support for alcohol or opioid dependence. It is also an ingredient in a specific combination medicine for weight management.
Key points
- Starting naltrexone while opioids are still in the body can trigger sudden, severe withdrawal.
- It blocks opioid pain medicines and changes overdose risk, so all treating clinicians need to know it is being used.
- Breathing difficulty, severe withdrawal, collapse or suspected opioid overdose needs emergency care.
Select a listed product and pack to order online. Supply depends on stock and destination rules; ask your doctor or pharmacist whether it suits you.
What Naltrexone is used for
Naltrexone may support treatment for alcohol dependence or opioid dependence after appropriate assessment. In a specific combination, it may be used as part of a broader weight-management plan.
How it works
Naltrexone blocks opioid receptors. This prevents opioids from producing their usual effects; it does not itself treat acute withdrawal and does not make opioid use safe.
Important safety checks
Current or recent opioid use (including some pain, cough and diarrhoea medicines) must be reviewed before treatment. Liver health, pregnancy and plans for surgery or emergency pain relief also matter. Trying to overcome the opioid blockade can cause fatal overdose, and opioid tolerance may be lower after naltrexone is stopped.
When to seek urgent care
Call emergency services for slow or stopped breathing, blue-grey lips or skin, inability to wake, collapse or suspected overdose. Seek urgent assessment for severe precipitated withdrawal, yellow skin or eyes, severe abdominal pain or a serious allergic reaction.
Further reading
What is naltrexone used for?
Naltrexone can help treat alcohol dependence or opioid dependence, but only after a proper assessment. Combined with bupropion, as in Contrave, it is also used for weight management.
How does naltrexone work?
Naltrexone blocks opioid receptors in the brain, which stops opioids from having their usual effects. It does not treat withdrawal and does not make opioid use safe.
Which products contain naltrexone?
Products containing naltrexone on SGMeds include Revia and Contrave. Compare their forms, strengths and pack sizes.
What is naltrexone called in other countries?
In other countries, naltrexone is also sold as Adepend. Brand names vary between countries, so compare products by their active ingredient.
How long does naltrexone take to work?
Naltrexone starts working in about an hour, and the effect lasts around 24 hours.
What are the side effects of naltrexone?
You may get nausea, dizziness or a headache. Less common effects include trouble sleeping, anxiety and stomach pain. Liver problems and depression are serious and need urgent medical attention.
Can naltrexone be taken with other medicines?
Naltrexone can interact with opioid painkillers and opioid cough medicines. If you have used opioids recently, tell your doctor or pharmacist before starting it, and ask them to check your other medicines.
How is naltrexone priced?
Each product on this page shows a price for each strength and pack size in Singapore dollars, converted from US dollars, so the exchange rate can change the final amount. Larger packs usually cost less per tablet.
Payment and prices →Do I need a prescription for naltrexone in Singapore?
No. SGMeds does not ask for a prescription to order naltrexone: we place the order with our pharmacy partner, which prepares it and arranges delivery on your behalf.
Ordering without a prescription →Where can I buy naltrexone in Singapore?
You can order naltrexone here on SGMeds: choose the product, strength and pack, then check out. We deliver to Singapore and Malaysia. Express shipping is tracked and takes up to 1 week, and Regular shipping takes up to 3 weeks.
How ordering works →