Medication-assisted relapse prevention

Man seeking medication-assisted relapse prevention treatment

A pill – naltrexone – that releases an opioid blocker into your bloodstream, so using heroin/opioids no longer affects you.

People committed to maintaining abstinence and who want to avoid taking opioids as part of their treatment.


  • Extra help for staying off drugs.
  • Prevents the reward or "high" if heroin/opioids are used.


  • Withdrawal symptoms you can’t do anything about and, in some cases, cravings.
  • If you need opioid painkillers, they will not work if you are taking naltrexone.

Staying away from drugs
Relapse prevention is about more than just medication. A number of options alongside psychosocial support/counselling can help you stay away from drugs. Any of these steps are a good start:

  • Remove the pressures that trigger craving: stop seeing your old drug-using friends; stop passing through places where you used to use; dispose of all drug-using equipment.
  • Try writing a list of the people, places and things that were associated with your drug use in the past. Then think of ways to avoid them.
  • Maybe consider deleting the numbers of your dealer(s) or drug-using friends from your mobile phone and changing your phone number to avoid contact from them.

Naltrexone is generally used as a next step after detoxification to try and prevent relapse to drug use. Because opioid antagonist treatments block the sites where opioids bind in the body, you won’t feel any drug effects if you use. However, because the binding sites are not activated, you may still get cravings. Overdoses and fatalities have occurred when people have overloaded their system with opioids after stopping taking naltrexone or trying to get rid of their cravings and/or overcome naltrexone’s effects.

Naltrexone has been used under sedation to try and force a quick withdrawal from drugs. This led to some serious side effects including vomiting, diarrhoea and delirium, and is not considered safe.

Taking naltrexone
Naltrexone comes in tablets of 50 mg and is taken orally. A common daily dose of naltrexone is 50 mg. Some physicians split this into two doses of 25 mg and others provide dosing three times per week (100 mg, 100 mg and 150 mg). You need to have stopped taking heroin/opioids and be opioid-free before starting naltrexone; otherwise you may experience precipitated withdrawal.

Are there any side effects?
Not everyone gets side effects; some of naltrexone’s more common side effects are:

  • nausea
  • headache
  • dizziness
  • fatigue
  • insomnia
  • anxiety
  • drowsiness.

Side effects often wear off over time; any new medication can take time to adjust to.