In this study, we evaluate the efficacy of multi‐family therapy at reducing the addiction severity and at improving the psychological and family dynamics of opiate addicts receiving methadone treatment at a public treatment center. The study compares multi‐family therapy with a reflecting team (MFT‐RT) and a standard treatment following a methadone maintenance treatment program. The results show that multi‐family therapy with a reflecting team effectively reduces the addiction severity in several of the areas evaluated and noted that this effect is superior to standard treatment. The psychotherapy patients showed improvement in the areas of employment and social support; their drug use diminished and their psychiatric condition improved. At the same time, they needed a lower daily dose of methadone. In addition, the group undergoing standard treatment showed a noteworthy deterioration in their medical condition. Both groups showed a significant increase in their alcohol use. When applied to family treatments, the systemic‐constructivist approach by the reflecting team offers combined techniques that can help improve care for the families of patients with addiction problems.