Like it or not, drugs are a fact of today's life and nothing will stop people taking them. The sensible thing to do is limit the worst effects. The worse thing about drugs is the dealers. They're the ones who target kids and cut drugs with all sorts of shite. The most effective way to remove dealers from the loop, in my opinion, is to legalise drugs and sell them in a controlled and monitored manner in Boots. The dealers are out of business at a stroke and clean drugs and needles can be sold at their proper cost along with a small tax element to fund centres where people can be treated for addiction. The need to steal to fund a habit would be drastically reduced, along with drug crime in general. Not everyone would take drugs of course, just because they're legal (I certainly wouldn't!), just as not everyone drinks and smokes.
