The heroin addiction relapse rate is very high. It is generally accepted that overcoming a heroin addiction is the toughest addiction to kick.
A report from AddictionSearch.com said statistics show that the average heroin addict "will stop and start detox 10 to 25 times in their lifetime relapsing to heroin use every time."
The main reason for heroin addiction relapse is that the body is so accustomed to heroin that the withdrawal symptoms when heroin is removed are severe. It's often easier for the addict to take more heroin than to continue treatment.
If an addict does get through the withdrawal symptoms long enough for the body to adjust, many of them then have to deal with psychological cravings for the drug and may have heroin addiction relapse.
There is simply no way to guarantee that a heroin addict will not have heroin addiction relapse. The web site Solutions4Recovery.com writes "the best-documented drug-free treatments are the therapeutic community residential programs lasting at least 3 to 6 months."