How does methadone work for heroin addiction?

Mutual support helps. Methadone replaces the heroin, releasing the addict from the time, energy and legal risks of using heroin. Consider using some of this time and energy to engage in a recovery process involving a mutual support group like narcotics anonymous.
Suppress withdrawl. The principal effects of Methadone maintenance are to relieve narcotic craving, suppress the abstinence syndrome, and block the euphoric effects associated with opiates. Methadone maintenance has been found to be medically safe and non-sedating.