Addicts cost taxpayers £800,000
A drug addict costs the taxpayer more than £800,000 over the addict's lifetime, a government review has said.
But it said this could be cut by more than £730,000 if they were successfully given treatment by the age of 21.
The report also said creating drug-free prisons was nearly impossible and raised the suggestion of supervised heroin injection for prisoners.
Auditors PricewaterhouseCoopers, the report's authors, looked at NHS costs and factors such as the cost of crime.
The report's authors also admitted that even the £800,000 cost of each addict was likely to be an underestimate because they used "the more conservative" figures.
Their calculations showed a female "problem drug user" costs the taxpayer £859,000 over her lifetime, with a male user costing slightly less, at £827,000.
There are thought to be about 350,000 problem drug users in Britain - which from the report's figures translates into the taxpayer paying out more than £300m on all of them during their lifetimes.
The authors also said: "The creation of drug-free prisons is an expensive option and was not considered to be practical in the current resource climate."
They added that addicts could be given supervised "retoxification" towards the end of their sentences so that they were less likely to overdose on their release.
The report pointed out the failings of mandatory drug tests, which have often been hailed by ministers as a success in reducing prison drug use.
It said: "Staff and prisoners generally felt that mandatory drug testing should not be used to monitor the behaviour of individuals since it was open to manipulation (with clean urine often being used as a currency), and other problems such as recreational users of cannabis moving to opiate use to avoid detection."