The heart stops and breathing stops. Heroin is one of the most difficult drugs to stop. The withdrawal effects of trying to stop without the aid of a treatment program are awful. If a person that wants to stops gets involved in a treatment program which includes methadone, the chances are better. I have met many users that feel good with the methadone and with the amounts of methadone lowered weekly, the plan is to usually be finished within a year.
Problems occur when the treatment is supplemented with an occasional use of heroin.
Only for the user that wants to quit. You must have the mental will to stop also. The methadone only takes away the physical withdrawal symptoms associated with stopping. I have met many people that have had success with methadone, but the ones who run into problems are the ones that stray with a shot of heroin once in awhile. 3 steps forward, one step back, as they say.