Currently taking revia (naltrexone) & experiencing abdominal pain, tiredness, headache. how long does it take for effects to subside after taking it for 5 weeks?

Revia (naltrexone) Reaction?: Can't speak specifically for you, but generally speaking if side-effects from any psychotropic medication continue for that long without diminishing in frequency/intensity, it's unlikely that they will go away without the med being discontinued.

Liver tox. opiateuse: Revia (naltrexone) is an opiate antagonist, used to block opiate induced euphoria. It also blocks alcohol but not opiod cravings. The effects noted--headache, abdominal pain and tiredness--can occur with Naltrexone but if persisting after five weeks, could indicate other problems such as liver toxicity or new opiod use. Contact your health provider to evaluate these symptoms as soon as possible.

Maybe change med: Iif you continue to experience intolerable, unpleasant side effects with revia, (naltrexone) you should notify your physician to consider switching to an alternate treatment. You should also have a thorough history, physical examination and bloodwork performed by your doctor to evaluate for any other medical isues including liver disease.