"Heroin prescription represents a contentious approach to treatment. Many would question whether giving users the drug that they are addicted to constitutes 'treatment' in the normal sense of the word. As with any form of substitution therapy, there is also the question of whether users can be moved on from their drug use – perhaps the fact that users are being prescribed their drug of choice (rather than a frequently unpopular alternative) may mean that users will find it even more difficult to move on to abstinence. There is insufficient evidence to answer this latter concern. However, what the evidence base does indicate is that, in the short term, heroin prescription appears to be an effective way to retain users in treatment who have a history of failing in other treatment settings, with consequent benefits in terms of reduced drug use, crime and social reintegration."
Lloyd, Charlie and McKeganey, Neil, "Drugs Research: An overview of evidence and questions for policy," Joseph Rowntree Foundation, London, England: June 2010.